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<small>'''''Synonyms / Brand Names: (+ )-methylamphetamine, (+)-(s)-deoxyephedrine, (+)-(s)-n-alpha-dimethylphenethylamine, (+)-2-(N-Methylamino)-1-phenylpropane, (+)-methamphetamine, (+)-methylamphetamine, (+)-n,alpha-dimethyl-beta-phenylethylamine, (+)-n,alpha-dimethylphenethylamine, (+)-n-methylamphetamine, (2S)-N-methyl-1-phenylpropan-2-amine, (s)-(+)-deoxyephedrine, (s)-(+)-methamphetamine, (s)-(+)-n,alpha,dimethylphenethylamine, (s)-methamphetamine, (s)-methylamphetamine, (s)-n,alpha-dimethylbenzeneethanamine, (s)-n,alpha-dimethylbenzeneethanoamine, 1-Phenyl-2-methylamino-propan, 1-Phenyl-2-methylaminopropane, 2S-(+)-Methamphetamine, D-(s)-methamphetamine, D-1-Phenyl-2-methylaminopropane, d-1-Phenyl-2-methylaminopropan, D-deoxyephedrine, D-methylamphetamine, D-methamphetamine, D-desoxyephedrine, D-n,alpha-dimethylphenethylamine, D-n-methylamphetamine, D-phenylisopropylmethylamine, Desoxyephedrine hydrochloride, L-methamphetamine, Metamfetamina, Metamfetaminum, Metamphetamine, Metanfetamina, Methamphetaminum, Methyl-beta-phenylisopropylamine, Methylamphetamine, N-Methyl-1-phenyl-2-propanamine, N-methyl-beta-phenylisopropylamin,, N-methyl-beta-phenylisopropylamine, N-methylamphetamine, S-(+)-methamphetamine, Ice, Meth, Desoxyn, Desyphed, Desyphed hydrochloride, Metamfetamine, Metamfetamine-m, Norodin, Speed, Stimulex
{{hatnote|This article is about the free base and salts of methamphetamine. "Meth" redirects here. For other uses, see [[Meth (disambiguation)]]}}
''''' </small>
{{Use dmy dates|date=April 2015}}
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{{Infobox drug
| verifiedrevid = 589084691
| IUPAC_name = ''N''-methyl-1-phenylpropan-2-amine
| image = methamphetamine.png
| alt = An image of the methamphetamine compound
| image2 = Methamphetamine molecule from xtal ball.png
| width2 = 250px
| alt2 = Ball-and-stick model of the methamphetamine molecule


{{CMG}}
<!--Clinical data-->
| tradename = Desoxyn
| Drugs.com = {{Drugs.com|monograph|methamphetamine-hydrochloride}}
| pregnancy_AU =
| pregnancy_US = C
| dependency_liability = ''Physical'': none<br />''Psychological'': high
| addiction_liability = Very high
| legal_AU = S8
| legal_CA = Schedule I
| legal_NZ = Class A
| legal_UK = Class A
| legal_US = Schedule II
| legal_UN = Psychotropic Schedule II
| legal_status = Rx
| licence_US = Desoxyn
| routes_of_administration= ''Medical'': oral<br>''Recreational'': oral, intravenous, insufflation, inhalation, suppository


==Dosing and Administration==
<!--Pharmacokinetic data-->
'''Attention Deficit Disorder with Hyperactivity'''<br>
| bioavailability= Oral: Varies widely<ref name="Pubchem1" /><br/>Rectal: 99%<br/>IV: 100%
For treatment of children 6 years or older
| protein_bound = Varies widely<ref name="Pubchem1">{{cite encyclopedia | title=Methamphetamine | section-url=https://pubchem.ncbi.nlm.nih.gov/compound/1206#section=Toxicity | work=PubChem Compound | publisher = National Center for Biotechnology Information | accessdate=31 December 2013 | section=Toxicity}}</ref>
with a behavioral syndrome characterized by moderate to severe distractibility, short attention span,
| metabolism =[[CYP2D6]],<ref name="FDA Pharmacokinetics">{{cite web | title = Adderall XR Prescribing Information | url = http://www.accessdata.fda.gov/drugsatfda_docs/label/2013/021303s026lbl.pdf | pages = 12–13 | work = United States Food and Drug Administration |date=December 2013 | accessdate = 30 December 2013 }}</ref> [[Dopamine β-hydroxylase|DBH]],<ref name="DBH ref">{{cite book | title=Foye's Principles of Medicinal Chemistry | year=2013 | publisher=Wolters Kluwer Health/Lippincott Williams & Wilkins | location=Philadelphia | isbn=1609133455 | page=648 | author=Lemke TL, Williams DA, Roche VF, Zito W|edition=7th ed. | quote=Alternatively, direct oxidation of amphetamine by DA β-hydroxylase can afford norephedrine.}}</ref> [[Flavin-containing monooxygenase|FMO3]],<ref name="FMO">{{cite journal | author = Krueger SK, Williams DE | title = Mammalian flavin-containing monooxygenases: structure/function, genetic polymorphisms and role in drug metabolism | journal = Pharmacol. Ther. | volume = 106 | issue = 3 | pages = 357–387 |date=June 2005 | pmid = 15922018 | pmc = 1828602 | doi = 10.1016/j.pharmthera.2005.01.001 }}</ref> [[butyrate-CoA ligase|XM-ligase]],<ref name="Benzoic1" /> and [[glycine N-acyltransferase|ACGNAT]]<ref name="Benzoic2" />
hyperactivity, emotional lability and impulsivity: an initial dose of 5 mg DESOXYN once or twice a
| elimination_half-life= 9–12&nbsp;hours<ref name="Schep"/>
day is recommended. Daily dosage may be raised in increments of 5 mg at weekly intervals until an
| excretion = [[Renal]]
optimum clinical response is achieved. The usual effective dose is 20 to 25 mg daily. The total daily
dose may be given in two divided doses daily.
<br>
<br>
'''For Obesity'''<br>
One 5 mg tablet should be taken one-half hour before each meal. Treatment should not exceed a few weeks in duration. Methamphetamine is not recommended for use as an
anorectic agent in children under 12 years of age.
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[[{{PAGENAME}}#FDA Package Insert Resources|FDA Package Insert Resources]]
<br></font size><small>Indications, Contraindications, Side Effects, Drug Interactions, etc.</small><font size="4"><br>
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[http://www.pace-med-apps.com/gfrcalc.htm Calculate Creatine Clearance]
<br></font size><small>On line calculator of your patients Cr Cl by a variety of formulas.</small><font size="4"><br>
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[http://home.earthlink.net/~sensei11/convert.htm Convert pounds to Kilograms]
<br></font size><small>On line calculator of your patients weight in pounds to Kg for dosing estimates.</small><font size="4"><br>
<br> [[{{PAGENAME}}#Publication Resources|Publication Resources]]
<br></font size><small>Recent articles, WikiDoc State of the Art Review, Textbook Information</small><font size="4"><br>
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[[{{PAGENAME}}#Trial Resources|Trial Resources]]
<br></font size><small>Ongoing Trials, Trial Results</small><font size="4"><br>
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[[{{PAGENAME}}#Guidelines & Evidence Based Medicine Resources|Guidelines & Evidence Based Medicine Resources]]
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[[{{PAGENAME}}#Media Resources|Media Resources]]
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[[{{PAGENAME}}#Patient Resources|Patient Resources]]
<br></font size><small>Discussion Groups, Handouts, Blogs, News, etc.</small><font size="4"><br>
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[[{{PAGENAME}}#International Resources|International Resources]]
<br></font size><small>en Español</small><font size="4"><br>
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==FDA Package Insert Resources==
<!--Identifiers-->
[[{{PAGENAME}} indications|Indications]]
| CASNo_Ref = {{cascite|correct|CAS}}
<br>
| CAS_number_Ref = {{cascite|correct|??}}
<br>
| CAS_number=537-46-2
[[{{PAGENAME}} contraindications|Contraindications]]
| ATC_prefix=N06
<br>
| ATC_suffix=BA03
<br>
| ATC_supplemental=
[[{{PAGENAME}} side effects|Side Effects]]
| ChEBI_Ref = {{ebicite|correct|EBI}}
<br>
| ChEBI = 6809
<br>
| IUPHAR_ligand = 4803
[[{{PAGENAME}} drug interactions|Drug Interactions]]
| PDB_ligand =
<br>
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
<br>
| StdInChI = 1S/C10H15N/c1-9(11-2)8-10-6-4-3-5-7-10/h3-7,9,11H,8H2,1-2H3
[[{{PAGENAME}} precautions|Precautions]]
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
<br>
| StdInChIKey = MYWUZJCMWCOHBA-UHFFFAOYSA-N
<br>
| PubChem=1206
[[{{PAGENAME}} overdose|Overdose]]
| DrugBank_Ref = {{drugbankcite|correct|drugbank}}
<br>
| DrugBank=DB01577
<br>
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
[[{{PAGENAME}} instructions for administration|Instructions for Administration]]
| ChemSpiderID = 1169
<br>
| NIAID_ChemDB =
<br>
| UNII_Ref = {{fdacite|correct|FDA}}
[[{{PAGENAME}} how supplied|How Supplied]]
| UNII = 44RAL3456C
<br>
| KEGG_Ref = {{keggcite|correct|kegg}}
<br>
| KEGG = D08187
[http://www.fda.gov/medwatch/SAFETY/2006/Apr_PIs/Desoxyn_PI.pdf FDA label]
| ChEMBL_Ref = {{ebicite|correct|EBI}}
<br>
| ChEMBL = 1201201
<br>
[http://google2.fda.gov/search?q={{urlencode:{{#if:{{{1|}}}|{{{1}}}|{{PAGENAME}}}}}}&x=0&y=0&client=FDA&site=FDA&lr=&proxystylesheet=FDA&output=xml_no_dtd&getfields=* FDA on {{PAGENAME}}]
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==Publication Resources==
<!--Chemical data-->
[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&db=pubmed&term={{urlencode:{{#if:{{{1|}}}|{{{1}}}|{{PAGENAME}}}}}} Most Recent Articles on {{#if:{{{1|}}}|{{{1}}}|{{PAGENAME}}}}]
| C=10 | H=15 | N=1
<br>
| molecular_weight = 149.2337 g/mol
<br>
| smiles = N(C(Cc1ccccc1)C)C
[http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=search&db=pubmed&term={{urlencode:{{#if:{{{1|}}}|{{{1}}}|{{PAGENAME}}}}}}%20AND%20systematic%5Bsb%5D  Review Articles on {{PAGENAME}}]
| InChI = 1/C10H15N/c1-9(11-2)8-10-6-4-3-5-7-10/h3-7,9,11H,8H2,1-2H3
<br>
| InChIKey = MYWUZJCMWCOHBA-UHFFFAOYAT
<br>
| synonyms = ''N''-methylamphetamine, desoxyephedrine
[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=search&db=pubmed&term={{urlencode:{{#if:{{{1|}}}|{{{1}}}|{{PAGENAME}}}}}}+AND+%28%28N+Engl+J+Med%5Bta%5D%29+OR+%28Lancet%5Bta%5D%29+OR+%28BMJ%5Bta%5D%29%29 Articles on {{PAGENAME}} in N Eng J Med, Lancet, BMJ]
| boiling_point = 212
<br>
| boiling_notes = <ref name="Pubchem2">{{cite encyclopedia | title=Methamphetamine | section-url=https://pubchem.ncbi.nlm.nih.gov/compound/1206#section=Chemical-and-Physical-Properties | work=PubChem Compound | publisher = National Center for Biotechnology Information | accessdate=31 December 2013 | section=Chemical and Physical Properties }}</ref> at {{nowrap|760 MM HG}}
<br>
| melting_point = 3
[[WikiDoc state of the art review on {{PAGENAME}}|WikiDoc State of the Art Review]]
| melting_notes = <ref name="Chemspider">{{cite encyclopedia | section-url=http://www.chemspider.com/Chemical-Structure.1169 | work=Chemspider | title=Methmphetamine | accessdate=3 January 2013 | section=Properties: Predicted – EP{{pipe}}Suite }}</ref>
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}}
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'''Methamphetamine'''{{#tag:ref|Synonyms and alternate spellings include: metamfetamine ([[International Nonproprietary Name|International Nonproprietary Name (INN)]]), ''N''-methylamphetamine, desoxyephedrine, Syndrox, and Desoxyn.<ref name="EMCDDA profile">{{cite web |url=http://www.emcdda.europa.eu/publications/drug-profiles/methamphetamine |title=Methamphetamine |date=16 August 2010 |work=Drug profiles |publisher=[[European Monitoring Centre for Drugs and Drug Addiction]] (EMCDDA) |accessdate=1 September 2011}}</ref><ref name="DB ID">{{cite encyclopedia | title=Methamphetamine | section-url=http://www.drugbank.ca/drugs/DB01577#identification | work=DrugBank | publisher= University of Alberta | accessdate=31 December 2013  | date=8 February 2013 | section=Identification }}</ref> Common slang terms for methamphetamine include: speed, meth, crystal, crystal meth, glass, shards, ice, and tic<ref>{{cite web|title=Meth Slang Names|url=http://www.methhelponline.com/meth-slang.htm|work=MethhelpOnline|accessdate=1 January 2014}}</ref> and, in New Zealand, "P".<ref>http://www.police.govt.nz/advice/drugs-and-alcohol/methamphetamine-and-law</ref>| group = "note" }} ({{IPAc-en|pron|ˌ|m|ɛ|θ|æ|m|ˈ|f|ɛ|t|əm|iː|n}}; contracted from {{nowrap|[[Methyl group|''N''-'''meth'''yl]]-[[amphetamine|'''a'''lpha-'''m'''ethyl'''ph'''en'''et'''hyl'''amine''']]}}) is a potent [[central nervous system]] (CNS) [[stimulant]] of the [[substituted phenethylamine|phenethylamine]] and [[substituted amphetamine|amphetamine]] [[chemical classification|classes]] that is used as a [[recreational drug use|recreational drug]] and, rarely, to treat [[attention deficit hyperactivity disorder]] (ADHD) and [[obesity]]. Methamphetamine exists as two [[enantiomer]]s, [[dextrorotation and levorotation|dextrorotary and levorotary]].{{#tag:ref|Enantiomers are molecules that are ''mirror images'' of one another; they are structurally identical, but of the opposite orientation.|group = "note"}} Dextromethamphetamine is a stronger CNS stimulant than [[levomethamphetamine]]; however, both are neurotoxic, addictive and produce the same toxicity symptoms at high doses. Although rarely prescribed due to the potential risks, methamphetamine hydrochloride is approved by the [[Food and Drug Administration|United States Food and Drug Administration]] (USFDA) under the trade name ''Desoxyn''. Recreationally, methamphetamine is used to [[aphrodisiac|increase sexual desire]], [[euphoria|lift the mood]], and [[wakefulness-promoting agent|increase energy]], allowing some users to engage in sexual activity continuously for several days straight.<!--READ THIS BEFORE EDITING THE LEAD. Every statement in the lead has a reference in the body of the article. Do not delete something because you think it's dubious; look for the statement ref in the body text first.-->
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==Trial Resources==
Methamphetamine may be sold illegally, either as pure dextromethamphetamine or in an [[racemic mixture|equal parts]] mixture of the right and left-handed molecules (i.e., 50%&nbsp;levomethamphetamine and 50%&nbsp;dextromethamphetamine). Both dextromethamphetamine and racemic methamphetamine are [[list of Schedule II drugs (US)|schedule II]] controlled substances in the United States. Similarly, the production, distribution, sale, and possession of methamphetamine is restricted or illegal in many other countries due to its placement in schedule II of the [[Convention on Psychotropic Substances|United Nations Convention on Psychotropic Substances]] treaty. In contrast, [[levomethamphetamine]] is an [[over-the-counter drug]] in the United States.<ref name="Vicks" group="note" /><!--READ THIS BEFORE EDITING THE LEAD. Every statement in the lead has a reference in the body of the article. Do not delete something because you think it's dubious; look for the statement ref in the body text first.-->
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==Guidelines & Evidence Based Medicine Resources==
In low doses, methamphetamine can cause an [[euphoria|elevated mood]] and increase alertness, concentration, and energy in fatigued individuals. At higher doses, it can induce [[stimulant psychosis#substituted amphetamines|psychosis]], [[rhabdomyolysis]] and [[cerebral hemorrhage]]. Methamphetamine is known to have a high potential for [[substance abuse|abuse]] and [[substance dependence|addiction]]. Heavy recreational use of methamphetamine may result in psychosis or lead to [[post-acute-withdrawal syndrome]], a withdrawal syndrome that can persist for months beyond the typical withdrawal period.<sup>[[#i|&#91;i&#93;]]</sup> Unlike [[amphetamine]], methamphetamine is [[neurotoxicity|neurotoxic]] to humans, damaging both [[dopamine]] and [[serotonin]] [[neuron]]s in the CNS.<sup>[[#i|&#91;i&#93;]]</sup> Contrary to the long-term use of amphetamine,<sup>[[#iii|&#91;iii&#93;]]</sup> there is evidence that methamphetamine causes brain damage from long-term use in humans;<sup>[[#ii|&#91;ii&#93;]]</sup> this damage includes adverse changes in brain structure and function, such as reductions in [[gray matter]] volume in several brain regions and adverse changes in markers of metabolic integrity.<sup>[[#ii|&#91;ii&#93;]]</sup><!--READ THIS BEFORE EDITING THE LEAD. Every statement in the lead has a reference in the body of the article. Do not delete something because you think it's dubious; look for the statement ref in the body text first.-->
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==Media Resources==
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==Patient Resources==
== Uses ==
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==International Resources==
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{{FDA}}


[[Category:Drugs]]
In the United States, methamphetamine hydrochloride, under the trade name ''Desoxyn'', has been approved by the FDA for treating [[attention deficit hyperactivity disorder|ADHD]] and [[obesity|exogenous obesity]] (obesity originating from factors outside the patient's control) in both adults and children;<ref name="Desoxyn" /><ref>{{Cite journal|url = http://www.nature.com/npp/journal/v37/n3/full/npp2011276a.html|title = Is Cognitive Functioning Impaired in Methamphetamine Users? A Critical Review|last = Hart|first = Carl|date = 16 November 2011|journal = Neuropsychopharmacology|doi = 10.1038/npp.2011.276|pmid = 22089317|access-date = 6 March 2015|last2 = Marvin|first2 = Caroline|last3 = Silver|first3 = Rae|last4 = Smith|first4 = Edward|volume=37|pmc=3260986|pages=586–608}}</ref> however, the FDA also indicates that the limited therapeutic usefulness of methamphetamine should be weighed against the inherent risks associated with its use.<ref name="Desoxyn" /> Methamphetamine is sometimes prescribed [[off label]] for [[narcolepsy]] and [[idiopathic hypersomnia]].<ref name="pmid8341891">{{vcite2 journal | vauthors = Mitler MM, Hajdukovic R, Erman MK | title = Treatment of narcolepsy with methamphetamine | journal = Sleep | volume = 16 | issue = 4 | pages = 306–317 | year = 1993 | pmid = 8341891 | pmc = 2267865 | doi = | url = }}</ref><ref>{{vcite2 journal | vauthors = Morgenthaler TI1, Kapur VK, Brown T, Swick TJ, Alessi C, Aurora RN, Boehlecke B, Chesson AL Jr, Friedman L, Maganti R, Owens J, Pancer J, Zak R; Standards of Practice Committee of the American Academy of Sleep Medicine. | title = Practice parameters for the treatment of narcolepsy and other hypersomnias of central origin. | journal = Sleep | volume =  | issue =  | pages =  | year = 2007 | pmid = 18246980 | pmc = 2276123 | doi = | url = }}</ref> In the United States, [[levomethamphetamine|methamphetamine's levorotary form]] is available in some over-the-counter nasal decongestant products, such as [[Vicks|Vicks VapoInhaler]].{{#tag:ref|The active ingredient in Vicks Vapoinhaler is listed as ''levmetamfetamine'', the [[International Nonproprietary Name|INN]] and [[United States Adopted Name|USAN]] of levomethamphetamine.<ref name="Vicks">{{cite encyclopedia | title=Vicks Vapoinhaler| section=Package Information | section-url=http://www.vicks.com/products/vapo-family/vapoinhaler-nasal-congestion-relief/| publisher=Vicks| accessdate=2 January 2014}}</ref><ref>{{cite encyclopedia | title=Levomethamphetamine| section=Identification | section-url=http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=36604#section=Identification | work=Pubchem Compound| publisher=National Center for Biotechnology Information | accessdate=2 January 2014}}</ref>|name="Vicks"|group = "note"}}
 
As methamphetamine is associated with a high potential for misuse, the drug is regulated under the [[Controlled Substances Act]] and is [[List of Schedule II drugs (US)|listed under schedule II]] in the United States.<ref name="Desoxyn" /> Methamphetamine hydrochloride dispensed in the United States is required to include the following [[boxed warning]]:<ref name="Desoxyn" /> {{cquote|Methamphetamine has a high potential for abuse. It should thus be tried only in weight reduction programs for patients in whom alternative therapy has been ineffective. Administration of methamphetamine for prolonged periods of time in obesity may lead to drug dependence and must be avoided. Particular attention should be paid to the possibility of subjects obtaining methamphetamine for non-therapeutic use or distribution to others, and the drug should be prescribed or dispensed sparingly. Misuse of methamphetamine may cause sudden death and serious cardiovascular adverse effects.}}
 
=== Recreational ===
{{Hatnote|See also: [[Party and play]] and the [[History and culture of substituted amphetamines#Recreational routes of administration|Recreational routes of methamphetamine administration]]}}
 
Methamphetamine is often used recreationally for its effects as a potent [[euphoriant]] and stimulant as well as [[aphrodisiac]] qualities.<ref name="SF Meth">{{cite AV media |date=August 2013 |title=San Francisco Meth Zombies |medium=TV documentary |url= |accessdate=4 January 2014 |publisher=National Geographic Channel |asin=B00EHAOBAO }}</ref> According to a [[National Geographic Channel|National Geographic]] TV documentary on methamphetamine, "an entire subculture known as party and play is based around methamphetamine use".<ref name="SF Meth" />  Members of this San Francisco sub-culture, which consists almost entirely of gay male methamphetamine users, will typically meet up through internet dating sites and have sex.<ref name="SF Meth" />  Due to its strong stimulant and aphrodisiac effects and inhibitory effect on [[ejaculation]], with repeated use, these sexual encounters will sometimes occur continuously for several days.<ref name="SF Meth" /> The crash following the use of methamphetamine in this manner is very often severe, with marked [[hypersomnia]].<ref name="SF Meth" />
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==Contraindications==
Methamphetamine is [[contraindicated]] in individuals with a history of [[substance use disorder]], [[heart disease]], or severe [[Irritability|agitation]] or anxiety, or in individuals currently experiencing [[arteriosclerosis]], [[glaucoma]],  [[hyperthyroidism]], or severe [[hypertension]].<ref name="Desoxyn" /> The USFDA states that individuals who have experienced [[hypersensitivity]] reactions to other stimulants in the past or are currently taking [[monoamine oxidase inhibitor]]s should not take methamphetamine.<ref name="Desoxyn" />  The USFDA also advises individuals with [[bipolar disorder]], [[Major depressive disorder|depression]], elevated [[blood pressure]], liver or kidney problems, [[mania]], [[psychosis]], [[Raynaud's phenomenon]], [[epileptic seizure|seizures]], [[thyroid]] problems, [[tic]]s, or [[Tourette syndrome]] to monitor their symptoms while taking methamphetamine.<ref name="Desoxyn" />  Due to the potential for stunted growth, the USFDA advises monitoring the height and weight of growing children and adolescents during treatment.<ref name="Desoxyn" />
 
== Side effects ==
 
=== Physical ===
 
The physical effects of methamphetamine can include [[Anorexia (symptom)|loss of appetite]], hyperactivity, [[dilated pupils]], [[Flushing (physiology)|flushed skin]], [[diaphoresis|excessive sweating]], [[Psychomotor agitation|increased movement]], dry mouth and [[bruxism|teeth grinding]] (leading to "[[meth mouth]]"), headache,  [[arrhythmias|irregular heartbeat]] (usually as [[tachycardia|accelerated heartbeat]] or [[bradycardia|slowed heartbeat]]), [[tachypnea|rapid breathing]], [[hypertension|high blood pressure]], [[hypotension|low blood pressure]], [[hyperthermia|high body temperature]], diarrhea, constipation, [[blurred vision]], [[dizziness]], [[Fasciculation|twitching]], [[numbness]], [[tremor]]s, dry skin, [[acne]], and [[pallor|pale appearance]].<ref name="Desoxyn" /><ref name="Westfall" /> Methamphetamine that is present in a mother's [[bloodstream]] can pass through the [[placenta]] to a [[fetus]] and is or be secreted into [[breast milk]].<ref name="pregnancy" /> Infants born to methamphetamine-abusing mothers were found to have a significantly smaller [[gestational]] age-adjusted head circumference and birth weight measurements.<ref name="pregnancy" /> Methamphetamine exposure was also associated with [[neonatal withdrawal]] symptoms of agitation, vomiting and fast breathing.<ref name="pregnancy">{{cite journal|author=Chomchai C, Na Manorom N, Watanarungsan P, Yossuck P, Chomchai S| pmid=15272773 |title=Methamphetamine abuse during pregnancy and its health impact on neonates born at Siriraj Hospital, Bangkok, Thailand. &#124; PubMed| publisher=| date=December 2010|volume=35|issue=1| journal=Southeast Asian J. Trop. Med. Public Health| pages=228–231}}</ref> This withdrawal syndrome is relatively mild and only requires medical intervention in approximately&nbsp;4% of cases.<ref name="pmid17990840"/>
 
==== Meth mouth ====
{{Main|Meth mouth}}
Methamphetamine users and addicts may lose their teeth abnormally quickly, regardless of the route of administration, from a condition informally known as [[meth mouth]].<ref name="pmid22782046" /> The condition is generally most severe in users who inject the drug, rather than those who smoke, ingest, or inhale it.<ref name="pmid22782046">{{cite journal |author=Hussain F, Frare RW, Py Berrios KL |title=Drug abuse identification and pain management in dental patients: a case study and literature review |journal=Gen. Dent. |volume=60 |issue=4 |pages=334–345 |year=2012 |pmid=22782046 |doi= |url=}}</ref>  According to the [[American Dental Association]], meth mouth "is probably caused by a combination of drug-induced psychological and physiological changes resulting in [[xerostomia]] (dry mouth), extended periods of poor [[oral hygiene]], frequent consumption of high-calorie, carbonated beverages and [[bruxism]] (teeth grinding and clenching)".<ref name="pmid22782046" /><ref name="ADA">{{cite web|url=http://www.ada.org/prof/resources/topics/methmouth.asp |title=Methamphetamine Use (Meth Mouth)|accessdate=December 2006 |publisher=American Dental Association |archiveurl =http://web.archive.org/web/20080601035323/http://www.ada.org/prof/resources/topics/methmouth.asp |archivedate = June 2008}}</ref> Many researchers suggest that methamphetamine-induced tooth decay is due to users' lifestyles, as dry mouth is also a side effect of other stimulants, which are not known to cause serious tooth decay. They suggest that the side effect has been exaggerated and stylized to deter potential users and stereotype current users.<ref name="pmid22089317">{{cite journal |author=Hart CL, Marvin CB, Silver R, Smith EE |title=Is cognitive functioning impaired in methamphetamine users? A critical review |journal=Neuropsychopharmacology |volume=37 |issue=3 |pages=586–608 |date=February 2012  |pmid=22089317 |pmc=3260986 |doi=10.1038/npp.2011.276 |url=}}</ref>
 
=== Psychological ===
The psychological effects of methamphetamine can include [[euphoria]], [[dysphoria]], changes in [[libido]], [[alertness]], apprehension, [[concentration]], decreased sense of fatigue, [[insomnia]] or [[wakefulness]], [[self-confidence]], sociability, irritability, restlessness, [[grandiosity]] and [[Fixation (psychology)|repetitive and obsessive]] behaviors.<ref name="Desoxyn">{{cite web| title=Desoxyn Prescribing Information| url=http://www.accessdata.fda.gov/drugsatfda_docs/label/2013/005378s028lbl.pdf|date=December 2013 |work=United States Food and Drug Administration| accessdate=6 January 2014}}</ref><ref name="Westfall">{{cite book | editor = Brunton LL, Chabner BA, Knollmann BC | title = Goodman & Gilman's Pharmacological Basis of Therapeutics | year = 2010 | publisher = McGraw-Hill | location = New York | isbn = 978-0-07-162442-8 | author = Westfall DP, Westfall TC | section = Miscellaneous Sympathomimetic Agonists | sectionurl = http://www.accessmedicine.com/content.aspx?aID=16661601 | edition = 12th }}</ref><ref name="Merck_Manual_Amphetamines">{{cite web | url = http://www.merckmanuals.com/professional/special_subjects/drug_use_and_dependence/amphetamines.html | author = O'Connor PG | title = Amphetamines | work = Merck Manual for Health Care Professionals | publisher = Merck |date=February 2012| accessdate = 8 May 2012 }}</ref> Methamphetamine use also has a high association with [[anxiety]], [[Major depressive disorder|depression]], [[Stimulant psychosis#substituted amphetamines|methamphetamine psychosis]], [[suicide]], and violent behaviors.<ref name="Darke-2008">{{cite journal | author = Darke S, Kaye S, McKetin R, Duflou J | title = Major physical and psychological harms of methamphetamine use | journal = Drug Alcohol Rev. | volume = 27 | issue = 3 | pages = 253–262 |date=May 2008 | pmid = 18368606 | doi = 10.1080/09595230801923702 }}</ref> Methamphetamine also has a very high [[addiction]] risk.<ref name="Desoxyn" />
 
=== Dependence, addiction, and withdrawal ===
{{See also|ΔFosB}}{{Psychostimulant addiction|Colorcode=yes|align=right}}
[[Drug tolerance|Tolerance]] is expected to develop with regular methamphetamine use and, when abused, this tolerance develops rapidly.<ref>{{cite web| last=O'Connor| first=Patrick| title=Amphetamines: Drug Use and Abuse| url=http://www.merckmanuals.com/home/special_subjects/drug_use_and_abuse/amphetamines.html| work=Merck Manual Home Health Handbook| publisher=Merck| accessdate=26 September 2013}}</ref><ref name="Cochrane Abuse">{{cite journal |author=Pérez-Mañá C, Castells X, Torrens M, Capellà D, Farre M |title=Efficacy of psychostimulant drugs for amphetamine abuse or dependence |journal=Cochrane Database Syst. Rev. |volume=9 |pages=CD009695 |year=2013 |pmid=23996457 |doi=10.1002/14651858.CD009695.pub2 |editor1-last=Pérez-Mañá |editor1-first=Clara }}</ref>
 
The evidence on effective treatments for amphetamine and methamphetamine dependence and abuse is limited.<ref name="Cochrane Addiction">{{cite journal |author=Srisurapanont M, Jarusuraisin N, Kittirattanapaiboon P |title=Treatment for amphetamine dependence and abuse |journal=Cochrane Database Syst. Rev. |volume= |issue=4 |pages=CD003022 |year=2001 |pmid=11687171 |doi=10.1002/14651858.CD003022 |quote=Although there are a variety of amphetamines and amphetamine derivatives, the word "amphetamines" in this review stands for amphetamine, dextroamphetamine and methamphetamine only. |editor1-last=Srisurapanont |editor1-first=Manit}}</ref> In light of this, [[fluoxetine]]{{#tag:ref|During short-term treatment, fluoxetine may decrease drug craving.<ref name="Cochrane Addiction" />| group = "note" }} and [[imipramine]]{{#tag:ref|During "medium-term treatment," imipramine may extend the duration of adherence to addiction treatment.<ref name="Cochrane Addiction" />| group = "note" }} appear to have some limited benefits in treating abuse and addiction, "no treatment has been demonstrated to be effective for the treatment of [methamphetamine] dependence and abuse".<ref name="Cochrane Addiction" />
 
In highly dependent amphetamine and methamphetamine abusers, "when chronic heavy users abruptly discontinue [methamphetamine] use, many report a time-limited withdrawal syndrome that occurs within 24&nbsp;hours of their last dose".<ref name="Cochrane Withdrawal">{{cite journal | author = Shoptaw SJ, Kao U, Heinzerling K, Ling W | title = Treatment for amphetamine withdrawal | journal = Cochrane Database Syst. Rev. | volume = | issue = 2 | pages = CD003021 | year = 2009 | pmid = 19370579 | doi = 10.1002/14651858.CD003021.pub2 | editor = Shoptaw SJ |quote = <br>The prevalence of this withdrawal syndrome is extremely common (Cantwell 1998; Gossop 1982) with 87.6% of 647 individuals with amphetamine dependence reporting six or more signs of amphetamine withdrawal listed in the DSM when the drug is not available (Schuckit 1999)&nbsp;... Withdrawal symptoms typically present within 24&nbsp;hours of the last use of amphetamine, with a withdrawal syndrome involving two general phases that can last 3 weeks or more. The first phase of this syndrome is the initial "crash" that resolves within about a week (Gossop 1982;McGregor 2005)}}</ref> Withdrawal symptoms in chronic, high-dose users are frequent, occurring in up to 87.6% of cases, and persist for three to four weeks with a marked "crash" phase occurring during the first week.<ref name="Cochrane Withdrawal" />  Methamphetamine withdrawal symptoms can include anxiety, [[Craving (withdrawal)|drug craving]], [[Dysphoria|dysphoric mood]], [[Fatigue (medical)|fatigue]], [[hyperphagia|increased appetite]], [[Psychomotor agitation|increased movement]] or [[psychomotor retardation|decreased movement]], [[anhedonia|lack of motivation]], [[insomnia|sleeplessness]] or [[hypersomnia|sleepiness]], and [[Lucid dream|vivid or lucid dreams]].<ref name="Cochrane Withdrawal" /> Withdrawal symptoms are associated with the degree of dependence (i.e., the extent of abuse).<ref name="Cochrane Withdrawal" /> The mental depression associated with methamphetamine withdrawal lasts longer and is more severe than that of [[cocaine]] withdrawal.<ref name="pmid17990840">{{cite journal|author=Winslow BT, Voorhees KI, Pehl KA |title=Methamphetamine abuse|journal=American Family Physician |volume=76 |issue=8 |pages=1169–1174 |year=2007 |pmid=17990840 |doi=}}</ref>
 
Current models of addiction from chronic drug use involve alterations in [[gene expression]] in certain parts of the brain.<ref name="Nestler, Hyman, and Malenka 2">{{cite journal |author=Hyman SE, Malenka RC, Nestler EJ |title=Neural mechanisms of addiction: the role of reward-related learning and memory |journal=Annu. Rev. Neurosci. |volume=29 |issue= |pages=565–598 |year=2006 |pmid=16776597 |doi=10.1146/annurev.neuro.29.051605.113009 |url=}}</ref><ref name="Nestler" />  The most important [[transcription factor]]s that produce these alterations are [[ΔFosB]], cyclic adenosine monophosphate ([[cyclic adenosine monophosphate|cAMP]]) response element binding protein ([[cAMP response element binding protein|CREB]]), and nuclear factor kappa B ([[nuclear factor kappa B|NFκB]]).<ref name="Nestler" /> ΔFosB is the most significant, since its overexpression in the [[nucleus accumbens]] is necessary and sufficient for many of the neural adaptations seen in drug addiction;<ref name="Nestler" /> it has been implicated in addictions to [[alcoholism|alcohol]], [[cannabinoid]]s, [[cocaine]], [[nicotine]], [[phencyclidine]], and [[substituted amphetamines]].<ref name="Nestler, Hyman, and Malenka 2" /><ref name="Nestler" /><ref name="Alcoholism ΔFosB">{{cite web | title=Alcoholism – Homo sapiens (human) | url=http://www.genome.jp/kegg-bin/show_pathway?hsa05034+2354 | work=KEGG Pathway | accessdate=10 April 2014 | author=Kanehisa Laboratories | date=2 August 2013}}</ref>  [[ΔJunD]] is the transcription factor which directly opposes ΔFosB.<ref name="Nestler" /> Increases in nucleus accumbens ΔJunD expression can reduce or, with a large increase, even block most of the neural alterations seen in chronic drug abuse (i.e., the alterations mediated by ΔFosB).<ref name="Nestler" /> ΔFosB also plays an important role in regulating behavioral responses to natural rewards, such as palatable food, sex, and exercise.<ref name="Nestler" /><ref name="ΔFosB reward">{{cite journal | author = Blum K, Werner T, Carnes S, Carnes P, Bowirrat A, Giordano J, Oscar-Berman M, Gold M | title = Sex, drugs, and rock 'n' roll: hypothesizing common mesolimbic activation as a function of reward gene polymorphisms | journal = J. Psychoactive Drugs | volume = 44 | issue = 1 | pages = 38–55 | year = 2012 | pmid = 22641964 | pmc = 4040958 | doi = 10.1080/02791072.2012.662112| quote = It has been found that deltaFosB gene in the NAc is critical for reinforcing effects of sexual reward. Pitchers and colleagues (2010) reported that sexual experience was shown to cause DeltaFosB accumulation in several limbic brain regions including the NAc, medial pre-frontal cortex, VTA, caudate, and putamen, but not the medial preoptic nucleus.&nbsp;...these findings support a critical role for DeltaFosB expression in the NAc in the reinforcing effects of sexual behavior and sexual experience-induced facilitation of sexual performance.&nbsp;... both drug addiction and sexual addiction represent pathological forms of neuroplasticity along with the emergence of aberrant behaviors involving a cascade of neurochemical changes mainly in the brain's rewarding circuitry.}}</ref> Since natural rewards, like drugs of abuse, induce ΔFosB, chronic acquisition of these rewards can result in a similar pathological addictive state.<ref name="Nestler" /><ref name="ΔFosB reward" /> Consequently, ΔFosB is the key transcription factor involved in methamphetamine addiction, especially methamphetamine-induced [[sex addiction]]s.<ref name="Nestler">{{cite journal | author = Robison AJ, Nestler EJ | title = Transcriptional and epigenetic mechanisms of addiction | journal = Nat. Rev. Neurosci. | volume = 12 | issue = 11 | pages = 623–637 |date=November 2011  | pmid = 21989194 | pmc = 3272277 | doi = 10.1038/nrn3111 | quote = ΔFosB has been linked directly to several addiction-related behaviors&nbsp;... Importantly, genetic or viral overexpression of ΔJunD, a dominant negative mutant of JunD which antagonizes ΔFosB- and other AP-1-mediated transcriptional activity, in the NAc or OFC blocks these key effects of drug exposure14,22–24. This indicates that ΔFosB is both necessary and sufficient for many of the changes wrought in the brain by chronic drug exposure. ΔFosB is also induced in D1-type NAc MSNs by chronic consumption of several natural rewards, including sucrose, high fat food, sex, wheel running, where it promotes that consumption14,26–30. This implicates ΔFosB in the regulation of natural rewards under normal conditions and perhaps during pathological addictive-like states. }}</ref><ref name="ΔFosB reward" /><ref name="Amph and sex addiction"><!--Supplemental primary source-->{{cite journal | author = Pitchers KK, Vialou V, Nestler EJ, Laviolette SR, Lehman MN, Coolen LM | title = Natural and drug rewards act on common neural plasticity mechanisms with ΔFosB as a key mediator | journal = J. Neurosci. | volume = 33 | issue = 8 | pages = 3434–3442 |date=February 2013  | pmid = 23426671 | pmc = 3865508 | doi = 10.1523/JNEUROSCI.4881-12.2013 | quote = Together, these findings demonstrate that drugs of abuse and natural reward behaviors act on common molecular and cellular mechanisms of plasticity that control vulnerability to drug addiction, and that this increased vulnerability is mediated by ΔFosB and its downstream transcriptional targets.}}</ref>  ΔFosB inhibitors (drugs that oppose its action) may be an effective treatment for addiction and addictive disorders.<ref name="Malenka_2009_04">{{cite book | author = Malenka RC, Nestler EJ, Hyman SE | editor = Sydor A, Brown RY | title = Molecular Neuropharmacology: A Foundation for Clinical Neuroscience | year = 2009 | publisher = McGraw-Hill Medical | location = New York | isbn = 9780071481274 | pages = 384–385 | edition = 2nd | chapter = Chapter 15: Reinforcement and addictive disorders }}</ref>
 
<!--DO NOT MOVE THIS ANCHOR-->
 
=== Neurotoxicity{{anchor|i}} ===
 
Unlike [[amphetamine]], methamphetamine is directly [[neurotoxic]] to dopamine neurons.<ref name = "Malenka">{{cite book | author = Malenka RC, Nestler EJ, Hyman SE | editor = Sydor A, Brown RY | title = Molecular Neuropharmacology: A Foundation for Clinical Neuroscience | year = 2009 | publisher = McGraw-Hill Medical | location = New York | isbn = 978-0-07-148127-4 | page = 370 | edition = 2nd | chapter = 15 | quote = Unlike cocaine and amphetamine, methamphetamine is directly toxic to midbrain dopamine neurons.}}</ref>  Moreover, methamphetamine abuse is associated with an increased risk of [[Parkinson's disease]] due to excessive pre-synaptic dopamine [[autoxidation]], a mechanism of neurotoxicity.<ref name="Cruickshank-2009">{{cite journal | author = Cruickshank CC, Dyer KR | title = A review of the clinical pharmacology of methamphetamine | journal = Addiction | volume = 104 | issue = 7 | pages = 1085–1099 |date=July 2009 | pmid = 19426289 | doi = 10.1111/j.1360-0443.2009.02564.x }}</ref><ref name="Thrash-">{{cite journal | author = Thrash B, Thiruchelvan K, Ahuja M, Suppiramaniam V, Dhanasekaran M | title = Methamphetamine-induced neurotoxicity: the road to Parkinson's disease | journal = Pharmacol Rep | volume = 61 | issue = 6 | pages = 966–977 | year = 2009 | pmid = 20081231 | doi = 10.1016/s1734-1140(09)70158-6| url = http://www.if-pan.krakow.pl/pjp/pdf/2009/6_966.pdf | format = PDF }}</ref><ref name="Autoxidation1">{{cite journal | author = Sulzer D, Zecca L | title = Intraneuronal dopamine-quinone synthesis: a review | journal = Neurotox. Res. | volume = 1 | issue = 3 | pages = 181–195 |date=February 2000 | pmid = 12835101 | doi = 10.1007/BF03033289 }}</ref><ref name="Autoxidation2">{{cite journal | author = Miyazaki I, Asanuma M | title = Dopaminergic neuron-specific oxidative stress caused by dopamine itself | journal = Acta Med. Okayama | volume = 62 | issue = 3 | pages = 141–150 |date=June 2008 | pmid = 18596830 | doi = }}</ref> Similar to the neurotoxic effects on the dopamine system, methamphetamine can also result in neurotoxicity to [[serotonin]] neurons.<ref name="pmid19328213">{{cite journal | author = Krasnova IN, Cadet JL | title = Methamphetamine toxicity and messengers of death | journal = Brain Res. Rev. | volume = 60 | issue = 2 | pages = 379–407 |date=May 2009 | pmid = 19328213 | pmc = 2731235 | doi = 10.1016/j.brainresrev.2009.03.002 |quote=Neuroimaging studies have revealed that METH can indeed cause neurodegenerative changes in the brains of human addicts (Aron and Paulus, 2007; Chang et al., 2007). These abnormalities include persistent decreases in the levels of dopamine transporters (DAT) in the orbitofrontal cortex, dorsolateral prefrontal cortex, and the caudate-putamen (McCann et al., 1998, 2008; Sekine et al., 2003; Volkow et al., 2001a, 2001c). The density of serotonin transporters (5-HTT) is also decreased in the midbrain, caudate, putamen, hypothalamus, thalamus, the orbitofrontal, temporal, and cingulate cortices of METH-dependent individuals (Sekine et al., 2006)&nbsp;...<br>Neuropsychological studies have detected deficits in attention, working memory, and decision-making in chronic METH addicts&nbsp;...<br> There is compelling evidence that the negative neuropsychiatric consequences of METH abuse are due, at least in part, to drug-induced neuropathological changes in the brains of these METH-exposed individuals&nbsp;...<br> Structural magnetic resonance imaging (MRI) studies in METH addicts have revealed substantial morphological changes in their brains. These include loss of gray matter in the cingulate, limbic and paralimbic cortices, significant shrinkage of hippocampi, and hypertrophy of white matter (Thompson et al., 2004). In addition, the brains of METH abusers show evidence of hyperintensities in white matter (Bae et al., 2006; Ernst et al., 2000), decreases in the neuronal marker, N-acetylaspartate (Ernst et al., 2000; Sung et al., 2007), reductions in a marker of metabolic integrity, creatine (Sekine et al., 2002) and increases in a marker of glial activation, myoinositol (Chang et al., 2002; Ernst et al., 2000; Sung et al., 2007; Yen et al., 1994). Elevated choline levels, which are indicative of increased cellular membrane synthesis and turnover are also evident in the frontal gray matter of METH abusers (Ernst et al., 2000; Salo et al., 2007; Taylor et al., 2007).}}</ref> It has been demonstrated that a high core temperature is correlated with an increase in the neurotoxic effects of methamphetamine.<ref>{{cite journal|author=Yuan J, Hatzidimitriou G, Suthar P, Mueller M, McCann U, Ricaurte G |title=Relationship between temperature, dopaminergic neurotoxicity, and plasma drug concentrations in methamphetamine-treated squirrel monkeys |journal=The Journal of Pharmacology and Experimental Therapeutics|volume=316 |issue=3 |pages=1210–1218 |date=March 2006 |pmid=16293712|doi=10.1124/jpet.105.096503}}</ref> As a result of methamphetamine-induced [[neurotoxicity]] to [[dopamine]] [[neurons]], chronic use may also lead to [[post-acute-withdrawal syndrome|Post-acute-withdrawals]] which persist beyond the withdrawal period for months, and even up to a year.<ref name="Cruickshank-2009" />
 
=== Sexually transmitted infection ===
 
Methamphetamine use was found to be related to higher frequencies of unprotected sexual intercourse in both [[HIV/AIDS|HIV-positive]] and unknown casual partners, an association more pronounced in HIV-positive participants.<ref name="STD" /> These findings suggest that methamphetamine use and engagement in unprotected anal intercourse are co-occurring risk behaviors, behaviors that potentially heighten the risk of HIV transmission among gay and bisexual men.<ref name="STD">{{cite journal|author= Halkitis PN, Pandey Mukherjee P, Palamar JJ| title=Longitudinal Modeling of Methamphetamine Use and Sexual Risk Behaviors in Gay and Bisexual Men| journal=AIDS and Behavior| volume=13| issue=4| pages=783–791| year=2008| pmid=18661225|doi=10.1007/s10461-008-9432-y}}</ref> Methamphetamine use allows users of both sexes to engage in prolonged sexual activity, which may cause genital sores and abrasions as well as [[priapism]] in men.<ref name="Desoxyn" /><ref name="Patrick Moore">{{cite web|author=Patrick Moore|url=http://www.villagevoice.com/2005-06-14/people/we-are-not-ok/|title=We Are Not OK|publisher=VillageVoice |date=June 2005 |accessdate=January 2011}}</ref> Methamphetamine may also cause sores and abrasions in the mouth via [[bruxism]], increasing the risk of sexually transmitted infection.<ref name="Desoxyn" /><ref name="Patrick Moore"/>
 
Besides the sexual transmission of HIV, it may also be transmitted between users who [[needle sharing|share a common needle]].<ref name="unsw" /> The level of needle sharing among methamphetamine users is similar to that among other drug injection users.<ref name="unsw">{{cite web| url=http://www.med.unsw.edu.au/NDARCWeb.nsf/resources/NDLERF_Methamphetamine/$file/NDLERF+USE+AND+HEALTH.pdf| archiveurl=http://web.archive.org/web/20080816134234/http://www.med.unsw.edu.au/NDARCWeb.nsf/resources/NDLERF_Methamphetamine/$file/NDLERF+USE+AND+HEALTH.pdf|archivedate=August 2008| format=PDF| title=Methamphetamine Use and Health &#124; UNSW: The University of New South Wales&nbsp;– Faculty of Medicine |accessdate=January 2011}}</ref>
 
== Overdose ==
 
A methamphetamine overdose may result in a wide range of symptoms.<ref name="Schep"/><ref name="Desoxyn" /> A moderate overdose of methamphetamine may induce symptoms such as: [[Cardiac dysrhythmia|abnormal heart rhythm]], confusion, [[dysuria|difficult and/or painful urination]], high or low blood pressure, [[hyperthermia|high body temperature]], [[hyperreflexia|over-active and/or over-responsive reflexes]], [[myalgia|muscle aches]], severe [[Psychomotor agitation|agitation]], [[tachypnea|rapid breathing]], [[tremor]], [[urinary hesitancy]], and [[urinary retention|an inability to pass urine]].<ref name="Schep"/><ref name="Westfall" />  An extremely large overdose may produce symptoms such as [[adrenergic storm]], [[methamphetamine psychosis]], [[anuria|substantially reduced or nil urine output]], [[cardiogenic shock]], [[cerebral hemorrhage|brain bleed]], [[circulatory collapse]], [[hyperpyrexia|dangerously high body temperature]], [[pulmonary hypertension]], [[kidney failure]], [[rhabdomyolysis]], [[serotonin syndrome]], and a form of [[stereotypy#Associated terms|stereotypy]] ("tweaking").{{#tag:ref|<ref name="Schep"/><ref name="Desoxyn" /><ref name="Westfall" /><ref name="Merck_Manual_Amphetamines" /><ref name="Albertson_2011">{{cite book| editor = Olson KR, Anderson IB, Benowitz NL, Blanc PD, Kearney TE, Kim-Katz SY, Wu AHB | title = Poisoning & Drug Overdose | author = Albertson TE| year = 2011 | publisher = McGraw-Hill Medical | location = New York | isbn = 978-0-07-166833-0 | chapter = Amphetamines | pages = 77–79 | edition = 6th }}</ref><ref>{{cite web | title = Amphetamine Poisoning | url = http://emergency.unboundmedicine.com/emergency/ub/view/5-Minute_Emergency_Consult/307063/all/Amphetamine_Poisoning | work = Emergency Central | publisher = Unbound Medicine | date = 11 February 2011| accessdate = 11 June 2013 | author = Oskie SM, Rhee JW }}</ref><ref name="pmid17874986">{{cite journal | author = Isbister GK, Buckley NA, Whyte IM | title = Serotonin toxicity: a practical approach to diagnosis and treatment | journal = Med. J. Aust. | volume = 187 | issue = 6 | pages = 361–365 |date=September 2007 | pmid = 17874986 | doi = | url = https://www.mja.com.au/system/files/issues/187_06_170907/isb10375_fm.pdf }}</ref>| group = "Refnote" }}  A methamphetamine overdose will likely also result in mild [[brain damage]] due to [[dopaminergic]] and [[serotonergic]] neurotoxicity.<ref name="Malenka" /><ref name="pmid19328213" /> Death from methamphetamine poisoning is typically preceded by convulsions and [[coma]].<ref name="Desoxyn" />
 
=== Emergency treatment ===
 
The USFDA states{{#tag:ref|They suggest consulting with a Certified Poison Control Center on treatment for up-to-date information, advice, and guidance.<ref name="Desoxyn" />| group = "note" }} that acute methamphetamine intoxication is largely managed by treating the symptoms and includes may initially include administration of [[activated charcoal]] and [[sedation]].<ref name="Schep"/> There is not enough evidence on [[hemodialysis]] or [[peritoneal dialysis]] in cases of methamphetamine intoxication to determine their usefulness.<ref name="Desoxyn" />  [[Forced acid diuresis]] (e.g., with [[vitamin C]]) will increase methamphetamine excretion but is not recommended as it may increase the risk of aggravating acidosis, or cause seizures or rhabdomyolysis.<ref name="Schep"/> Hypertension presents a risk for [[intracranial hemorrhage]] and, if severe, is typically treated with intravenous [[phentolamine]] or [[nitroprusside]].<ref name="Schep"/>  Blood pressure often drops gradually following sufficient sedation with a [[benzodiazepine]] and providing a calming environment.<ref name="Schep"/> [[Chlorpromazine]] may be useful in decreasing the stimulant and CNS effects of a methamphetamine overdose.<ref name="Desoxyn" /> The use of a nonselective [[beta blocker]] may be required to control increased heart rate.<ref name="Schep"/>
 
=== Psychosis ===
{{Main section|Stimulant psychosis|Substituted amphetamines}}
 
Abuse of methamphetamine can result in a stimulant psychosis which may present with a variety of symptoms (e.g. [[paranoia]], [[hallucination]]s, [[delirium]], [[delusion]]s).<ref name="Schep"/><ref name="Cochrane" />  A [[Cochrane Collaboration]] review on treatment for amphetamine, dextroamphetamine, and methamphetamine abuse-induced psychosis states that about&nbsp;5–15% of users fail to recover completely.<ref name="Cochrane">{{cite journal | editor = Shoptaw SJ, Ali R | author = Shoptaw SJ, Kao U, Ling W | title = Treatment for amphetamine psychosis | journal = Cochrane Database Syst. Rev. | volume = | issue = 1 | pages = CD003026 | year = 2009 | pmid = 19160215 | doi = 10.1002/14651858.CD003026.pub3 | quote=A minority of individuals who use amphetamines develop full-blown psychosis requiring care at emergency departments or psychiatric hospitals. In such cases, symptoms of amphetamine psychosis commonly include paranoid and persecutory delusions as well as auditory and visual hallucinations in the presence of extreme agitation. More common (about 18%) is for frequent amphetamine users to report psychotic symptoms that are sub-clinical and that do not require high-intensity intervention&nbsp;...<br>About&nbsp;5–15% of the users who develop an amphetamine psychosis fail to recover completely (Hofmann 1983)&nbsp;...<br>Findings from one trial indicate use of antipsychotic medications effectively resolves symptoms of acute amphetamine psychosis.}}</ref><ref name="Hofmann">{{cite book | author = Hofmann FG | title = A Handbook on Drug and Alcohol Abuse: The Biomedical Aspects | publisher = Oxford University Press | isbn =  978-0-19-503057-0 | location = New York | year = 1983 | page = 329 | edition = 2nd }}</ref>  The same review asserts that, based upon at least one trial, [[antipsychotic]] medications effectively resolve the symptoms of acute amphetamine psychosis.<ref name="Cochrane" /> [[Stimulant psychosis#Substituted amphetamines|Methamphetamine psychosis]] may also develop occasionally as a treatment-emergent side effect.<ref name="Berman-2009">{{cite journal | author = Berman SM, Kuczenski R, McCracken JT, London ED | title = Potential adverse effects of amphetamine treatment on brain and behavior: a review | journal = Mol. Psychiatry | volume = 14 | issue = 2 | pages = 123–142 |date=February 2009 | pmid = 18698321 | pmc = 2670101 | doi = 10.1038/mp.2008.90 }}</ref>
 
== Interactions ==
 
Methamphetamine is metabolized by the liver enzyme [[CYP2D6]], so CYP2D6 inhibitors (e.g., [[selective serotonin reuptake inhibitor]]s (SSRIs)) will prolong the [[elimination half-life]] of methamphetamine.<ref name="DrugBank Enzymes">{{cite encyclopedia | title=Methamphetamine | section-url=http://www.drugbank.ca/drugs/DB01577#enzymes | work=DrugBank | publisher= University of Alberta | accessdate=31 December 2013  | date=8 February 2013 | section=Enzymes }}</ref> Methamphetamine also interacts with [[monoamine oxidase inhibitors]] (MAOIs), since both MAOIs and methamphetamine increase plasma catecholamines; therefore, concurrent use of both is dangerous.<ref name="Desoxyn" />  Methamphetamine may decrease the effects of [[sedative]]s and [[depressant]]s and increase the effects of [[antidepressant]]s and other [[stimulant]]s as well.<ref name="Desoxyn" />  Methamphetamine may counteract the effects of [[antihypertensives]] and [[antipsychotic]]s due to its effects on the cardiovascular system and cognition respectively.<ref name="Desoxyn" />  The [[pH]] of gastrointestinal content and urine affects the absorption and excretion of methamphetamine.<ref name="Desoxyn" />  Specifically, acidic substances will reduce the absorption of methamphetamine and increase urinary excretion, while alkaline substances do the opposite.<ref name="Desoxyn" />  Due to the effect pH has on absorption, [[proton pump inhibitor]]s, which reduce [[gastric acid]], are known to interact with methamphetamine.<ref name="Desoxyn" />
 
== Pharmacology ==
[[File:Amphetamine mechanism of action.svg|300px|right|thumb|This illustration depicts the normal operation of the [[dopaminergic]] terminal to the left, and the dopaminergic terminal in presence of methamphetamine to the right. Methamphetamine reverses the action of the dopamine transporter (DAT) by activating [[TAAR1]] (not shown).  TAAR1 activation also causes some of the dopamine transporters to move into the presynaptic neuron and cease transport (not shown). At VMAT2 (labeled VMAT), methamphetamine causes dopamine efflux (release).|alt=An image of methamphetamine pharmacodynamics]]
 
Amphetamines, in general, act as monoamine releasing agents and reuptake inhibitors.  They inhibit [[VMAT-2]], preventing packaging of [[monoamines]] into vesicles.  As these monoamine neurotransmitters remain in the cytoplasm at an ever-climbing level, the gradient for their transporters becomes progressively less favorable, which, in combination with [[dopamine transporter]] [[phosphorylation]] caused by amphetamines, causes the transporters to work in reverse, resulting in monoamine release.  There is also some evidence that amphetamines act as [[monoamine oxidase inhibitors]], amplifying this effect by preventing degradation of these neurotransmitters.{{mcn|date=March 2015}}
 
=== Pharmacodynamics{{anchor|ii}} ===
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Like amphetamine, methamphetamine has been identified as a potent [[full agonist]] of [[TAAR1|trace amine-associated receptor 1]] (TAAR1), a [[G protein-coupled receptor]] (GPCR) that regulates brain [[catecholamine]] systems.<ref name="Miller" /><ref name="Meth Targets" /> Activation of TAAR1, via [[adenylyl cyclase]], increases [[cyclic adenosine monophosphate]] (cAMP) production and either completely inhibits or reverses the transport direction of the [[dopamine transporter]] (DAT), [[norepinephrine transporter]] (NET), and [[serotonin transporter]] (SERT).<ref name="Miller" /><ref name="pmid11459929">{{cite journal | author = Borowsky B, Adham N, Jones KA, Raddatz R, Artymyshyn R, Ogozalek KL, Durkin MM, Lakhlani PP, Bonini JA, Pathirana S, Boyle N, Pu X, Kouranova E, Lichtblau H, Ochoa FY, Branchek TA, Gerald C | title = Trace amines: identification of a family of mammalian G protein-coupled receptors | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 98 | issue = 16 | pages = 8966–8971 |date=July 2001 | pmid = 11459929 | pmc = 55357 | doi = 10.1073/pnas.151105198}}</ref> When methamphetamine binds to TAAR1, it triggers transporter [[phosphorylation]] via [[protein kinase A]] (PKA) and [[protein kinase C]] (PKC) signaling, ultimately resulting in the [[endocytosis|internalization]] or reverse function of [[monoamine transporter]]s.<ref name="Miller" /><ref name="Xie and Miller 2009">{{cite journal | author = Xie Z, Miller GM | title = A receptor mechanism for methamphetamine action in dopamine transporter regulation in brain | journal = J. Pharmacol. Exp. Ther. | volume = 330 | issue = 1 | pages = 316–325 |date=July 2009 | pmid = 19364908 | pmc = 2700171 | doi = 10.1124/jpet.109.153775 }}</ref> Other [[Membrane transport protein|transporters]] that methamphetamine is known to inhibit are [[vesicular monoamine transporter 1]] (VMAT1), [[vesicular monoamine transporter 2]] (VMAT2), [[SLC22A3]], and [[SLC22A5]].<ref name="Meth Transporters">{{cite encyclopedia | title=Methamphetamine | section-url=http://www.drugbank.ca/drugs/DB01577#transporters | work=DrugBank | publisher= University of Alberta | accessdate=31 December 2013 | date=8 February 2013 | section=Transporters}}</ref> SLC22A3 is an extraneuronal monoamine transporter that is present in [[astrocyte]]s and SLC22A5 is a high-affinity [[carnitine]] transporter.<ref name="Meth Targets" /><ref name="pmid13677912">{{cite journal | author = Inazu M, Takeda H, Matsumiya T | title = [The role of glial monoamine transporters in the central nervous system] | language = Japanese | journal = Nihon Shinkei Seishin Yakurigaku Zasshi | volume = 23 | issue = 4 | pages = 171–178 |date=August 2003 | pmid = 13677912 | doi = }}</ref> When methamphetamine interacts with VMAT2, it induces a release of monoamines from the [[synaptic vesicle]]s (vesicles that stores monoamines) into the [[cytosol]] (intracellular fluid) of the [[presynaptic neuron]].<ref name="E Weihe" />
 
Methamphetamine is also an [[agonist]] of the [[alpha-2 adrenergic receptor]]s and [[sigma receptor]]s, and inhibits [[vesicular monoamine transporter 1]] (VMAT1), [[monoamine oxidase B]] (MAO-B), and [[monoamine oxidase A]] (MAO-A).<ref name="Meth Targets" /><ref name="Sigma">{{cite journal | author = Kaushal N, Matsumoto RR | title = Role of sigma receptors in methamphetamine-induced neurotoxicity | journal = Curr Neuropharmacol | volume = 9 | issue = 1 | pages = 54–57 |date=March 2011  | pmid = 21886562 | pmc = 3137201 | doi = 10.2174/157015911795016930 | url = }}</ref><ref name="SigmaB">{{cite journal | author = Rodvelt KR, Miller DK | title = Could sigma receptor ligands be a treatment for methamphetamine addiction? | journal = Curr Drug Abuse Rev | volume = 3 | issue = 3 | pages = 156–162 |date=September 2010  | pmid = 21054260 | doi = 10.2174/1874473711003030156| url = }}</ref> Methamphetamine is known to inhibit the CYP2D6 liver enzyme as well.<ref name="DrugBank Enzymes" />  Dextromethamphetamine is a stronger [[psychostimulant]], but levomethamphetamine has a longer half-life and is [[central nervous system|CNS]]-active with weaker effects (approximately one-tenth) on striatal dopamine and shorter perceived effects among addicts.<ref name="Melega">{{cite journal | author = Melega WP, Cho AK, Schmitz D, Kuczenski R, Segal DS | title = l-methamphetamine pharmacokinetics and pharmacodynamics for assessment of in vivo deprenyl-derived l-methamphetamine | journal = J. Pharmacol. Exp. Ther. | volume = 288 | issue = 2 | pages = 752–758 |date=February 1999 | pmid = 9918585 | doi = }}</ref><ref name="Kuczenski">{{cite journal | author = Kuczenski R, Segal DS, Cho AK, Melega W | title = Hippocampus norepinephrine, caudate dopamine and serotonin, and behavioral responses to the stereoisomers of amphetamine and methamphetamine | journal = J. Neurosci. | volume = 15 | issue = 2 | pages = 1308–1317 |date=February 1995 | pmid = 7869099 | doi = }}</ref><ref name="Mendelson">{{cite journal | author = Mendelson J, Uemura N, Harris D, Nath RP, Fernandez E, Jacob P, Everhart ET, Jones RT | title = Human pharmacology of the methamphetamine stereoisomers | journal = Clin. Pharmacol. Ther. | volume = 80 | issue = 4 | pages = 403–420 |date=October 2006 | pmid = 17015058 | doi = 10.1016/j.clpt.2006.06.013 }}</ref>  At high doses, both enantiomers of methamphetamine can induce [[stereotypy]] and [[methamphetamine psychosis]],<ref name="Kuczenski"/> but levomethamphetamine is less desired by recreational drug users because of its weaker pharmacodynamic profile.<ref name="Mendelson"/>
 
Although all the mechanisms are not fully understood, methamphetamine is a known neurotoxin in both lab animals and humans.<ref name="Malenka" /><ref name="pmid19328213" /><ref>{{cite journal|author=Itzhak Y, Martin JL, Ali SF |title=Methamphetamine-induced dopaminergic neurotoxicity in mice: long-lasting sensitization to the locomotor stimulation and desensitization to the rewarding effects of methamphetamine |journal=Progress in Neuro-psychopharmacology & Biological Psychiatry |volume=26 |issue=6|pages=1177–1183 |date=October 2002 |pmid=12452543 |doi=10.1016/S0278-5846(02)00257-9}}</ref><ref>{{cite journal|author=Davidson C, Gow AJ, Lee TH, Ellinwood EH |title=Methamphetamine neurotoxicity: necrotic and apoptotic mechanisms and relevance to human abuse and treatment |journal=Brain Research. Brain Research Reviews |volume=36 |issue=1 |pages=1–22 |date=August 2001 |pmid=11516769 |doi=10.1016/S0165-0173(01)00054-6}}</ref> Beyond neurotoxicity, [[magnetic resonance imaging]] studies on human methamphetamine addicts and abusers indicate adverse [[neuroplastic]] changes, such as significant abnormalities in various brain structures.<ref name="pmid19328213" /> In particular, methamphetamine appears to cause [[white matter]] [[hyperintensity]] and [[hypertrophy]], marked shrinkage of [[hippocampi]], and a reduction in [[gray matter]] in the [[cingulate cortex]], [[limbic cortex]], and [[paralimbic cortex]].<ref name="pmid19328213" /> Moreover, there are adverse changes in various metabolic markers of metabolic integrity or synthesis in methamphetamine abusers, such as reductions in [[N-acetylaspartate|''N''-acetylaspartate]] and [[creatine]] as well as elevated [[choline]] and [[myoinositol]] levels.<ref name="pmid19328213" />
 
==== Comparison to amphetamine pharmacodynamics{{anchor|iii}} ====
<!--DO NOT MOVE THIS ANCHOR-->
Both amphetamine and methamphetamine are potent [[central nervous system|CNS]] stimulants with a few [[biomolecular target]]s and affected transporters in common; however, there are important [[pharmacodynamics|pharmacodynamic]] differences between the two compounds.{{#tag:ref|<ref name="Meth Targets">{{cite encyclopedia | title=Methamphetamine | section-url=http://www.drugbank.ca/drugs/DB01577#targets | work=DrugBank | publisher= University of Alberta | accessdate=31 December 2013 | date=8 February 2013 | section=Targets }}</ref><ref name="Meth Transporters" /><ref name="Amph DB Transporters">{{cite web | title=Amphetamine | section-url=http://www.drugbank.ca/drugs/DB00182#transporters | work=DrugBank | publisher= University of Alberta | accessdate=13 October 2013 | date=8 February 2013 | section=Transporters }}</ref><ref name="Amph DB Targets">{{cite encyclopedia | title=Amphetamine | section-url=http://www.drugbank.ca/drugs/DB00182#targets | work=DrugBank | publisher= University of Alberta | accessdate=13 October 2013 | date=8 February 2013 | section=Targets }}</ref><ref name="Amph PC Targets">{{cite encyclopedia | title=Amphetamine | url=http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=3007 | work=PubChem Compound | publisher = National Center for Biotechnology Information | accessdate=13 October 2013 }}</ref>| group = "Refnote" }}  Both compounds are potent [[trace amine-associated receptor 1]] (TAAR1) agonists (causing non-competitive inhibition of [[Dopamine transporter|DAT]], [[Norepinephrine transporter|NET]], and [[Serotonin transporter|SERT]]) and inhibitors of [[VMAT2]], [[SLC22A3]], and [[SLC22A5]].{{#tag:ref|<ref name="Miller">{{cite journal | author = Miller GM | title = The emerging role of trace amine-associated receptor 1 in the functional regulation of monoamine transporters and dopaminergic activity | journal = J. Neurochem. | volume = 116 | issue = 2 | pages = 164–176 |date=January 2011 | pmid = 21073468 | pmc = 3005101 | doi = 10.1111/j.1471-4159.2010.07109.x }}</ref><ref name="Meth Transporters" /><ref name="E Weihe">{{cite journal | author = Eiden LE, Weihe E | title = VMAT2: a dynamic regulator of brain monoaminergic neuronal function interacting with drugs of abuse | journal = Ann. N. Y. Acad. Sci. | volume = 1216 | issue = | pages = 86–98 |date=January 2011 | pmid = 21272013 | doi = 10.1111/j.1749-6632.2010.05906.x }}</ref><ref name="Amph DB Transporters" />| group = "Refnote" }} However, methamphetamine appears to bind at a different site at VMAT2 than amphetamine.<ref name="VMAT2 amph vs meth">{{cite journal |author=Sulzer D, Sonders MS, Poulsen NW, Galli A |title=Mechanisms of neurotransmitter release by amphetamines: a review |journal=Prog. Neurobiol. |volume=75 |issue=6 |pages=406–433 |date=April 2005 |pmid=15955613 |doi=10.1016/j.pneurobio.2005.04.003 |url=|quote=They also demonstrated competition for binding between METH and reserpine, suggesting they might bind to the same site on VMAT. George Uhl's laboratory similarly reported that AMPH displaced the VMAT2 blocker tetrabenazine (Gonzalez et al., 1994). It should be noted that tetrabenazine and reserpine are thought to bind to different sites on VMAT (Schuldiner et al., 1993a)}}</ref> Methamphetamine also inhibits [[VMAT1]], has [[agonist]] activity at all [[alpha-2 adrenergic receptor]] and [[sigma receptor]] subtypes, and is directly toxic to dopamine neurons in humans, whereas there is no evidence of acute amphetamine toxicity in humans.<ref name="Malenka" /><ref name="pmid19328213" /><ref name="Meth Targets" /><ref name="Sigma" /> Sigma receptor activity is known to potentiate the stimulant and neurotoxic effects of methamphetamine.<ref name="Sigma" /><ref name="SigmaB" /><!--Amphetamine is an agonist of [[cocaine and amphetamine regulated transcript]] (CART), a psychostimulant neuropeptide with neurogenerative and neuroprotective effects ''in vitro'';<ref name="Amph DB Targets" /><ref name="Amph PC Targets" /> in contrast, the limited available research on the association between methamphetamine and CART in humans suggests methamphetamine has no significant effects on the neuropeptide.<ref name="Meth Targets" /><ref name="pmid17105939">{{cite journal |author=Morio A, Ujike H, Nomura A, Tanaka Y, Morita Y, Otani K, Kishimoto M, Harano M, Inada T, Komiyama T, Yamada M, Sekine Y, Iwata N, Iyo M, Sora I, Ozaki N, Kuroda S |title=No association between CART (cocaine- and amphetamine-regulated transcript) gene and methamphetamine dependence |journal=Ann. N. Y. Acad. Sci. |volume=1074 |issue= |pages=411–417 |date=August 2006 |pmid=17105939 |doi=10.1196/annals.1369.041 |url=}}</ref>-->
 
In contrast to the adverse neuroplastic effects evident in methamphetamine addicts and abusers, long-term use of amphetamine or methylphenidate at therapeutic doses appears to produce beneficial changes in brain function and structure, such as normalization of the [[right caudate nucleus]].<ref name="Neuroplasticity 1">{{cite journal |author=Hart H, Radua J, Nakao T, Mataix-Cols D, Rubia K |title=Meta-analysis of functional magnetic resonance imaging studies of inhibition and attention in attention-deficit/hyperactivity disorder: exploring task-specific, stimulant medication, and age effects |journal=JAMA Psychiatry |volume=70 |issue=2 |pages=185–198 |date=February 2013 |pmid=23247506 |doi=10.1001/jamapsychiatry.2013.277 |url=}}</ref><ref name="Neuroplasticity 2">{{cite journal |author=Spencer TJ, Brown A, Seidman LJ, Valera EM, Makris N, Lomedico A, Faraone SV, Biederman J |title=Effect of psychostimulants on brain structure and function in ADHD: a qualitative literature review of magnetic resonance imaging-based neuroimaging studies |journal=J. Clin. Psychiatry |volume=74 |issue=9 |pages=902–917 |date=September 2013 |pmid=24107764 |doi=10.4088/JCP.12r08287 |url= |pmc=3801446}}</ref>
 
=== Pharmacokinetics ===
 
Following oral administration, methamphetamine is well-absorbed into the bloodstream, with peak plasma methamphetamine concentrations achieved in approximately 3.13–6.3&nbsp;hours post ingestion.<ref name="DB Pharmacology">{{cite encyclopedia | title=Methamphetamine | section-url=http://www.drugbank.ca/drugs/DB01577#pharmacology | work=DrugBank | publisher= University of Alberta | accessdate=31 December 2013  | date=8 February 2013 | section=Pharmacology }}</ref> Methamphetamine is also well absorbed following inhalation and following intranasal administration.<ref name="Schep" /> Due to the high lipophilicity of methamphetamine, it can readily move through the [[blood–brain barrier]] faster than other stimulants, where it is more resistant to degradation by [[monoamine oxidase]].<ref name="Schep"/><ref name="DB Pharmacology" /> The amphetamine metabolite peaks at 10–24&nbsp;hours.<ref name="Schep" /> It is excreted by the kidneys, with the rate of excretion into the urine heavily influenced by urinary pH.<ref name="Desoxyn" /><ref name="DB Pharmacology" /> When taken orally, 30–54% of the dose is excreted in urine as methamphetamine and 10–23% as amphetamine.<ref name="DB Pharmacology" /> Following IV doses, about&nbsp;45% is excreted as methamphetamine and 7% as amphetamine.<ref name="DB Pharmacology" /> The [[half-life]] of methamphetamine is variable with a mean value of between 5 and 12&nbsp;hours.<ref name="Schep">{{cite journal |author=Schep LJ, Slaughter RJ, Beasley DM |title=The clinical toxicology of metamfetamine |journal=Clinical Toxicology (Philadelphia, Pa.) |volume=48 |issue=7 |pages=675–694 |date=August 2010 |pmid=20849327 |doi=10.3109/15563650.2010.516752|issn=1556-3650}}</ref><ref name="DB Pharmacology" />
 
[[CYP2D6]], [[dopamine β-hydroxylase]], [[flavin-containing monooxygenase]], [[butyrate-CoA ligase]], and [[glycine N-acyltransferase]] are the enzymes known to metabolize methamphetamine or its metabolites in humans.<ref name="DBH ref" /><ref name="FMO" /><ref name="Benzoic1">{{cite encyclopedia | title=butyrate-CoA ligase| url=http://www.brenda-enzymes.org/php/result_flat.php4?ecno=6.2.1.2&Suchword=&organism%5B%5D=Homo+sapiens&show_tm=0| work=BRENDA| publisher=Technische Universität Braunschweig.| accessdate=7 May 2014| section=Substrate/Product}}</ref><ref name="Benzoic2">{{cite encyclopedia | title=glycine N-acyltransferase| url=http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.1.13&Suchword=&organism%5B%5D=Homo+sapiens&show_tm=0| work=BRENDA| publisher=Technische Universität Braunschweig.| accessdate=7 May 2014| section=Substrate/Product}}</ref><ref name="DrugBank Enzymes">{{cite encyclopedia | title=Amphetamine | section-url=http://www.drugbank.ca/drugs/DB00182#enzymes | work=DrugBank | publisher= University of Alberta | accessdate=30 September 2013 | date=8 February 2013 | section=Enzymes }}</ref> The primary metabolites are amphetamine and [[pholedrine|4-hydroxymethamphetamine]]; other minor metabolites include: {{nowrap|[[4-hydroxyamphetamine]]}}, {{nowrap|[[4-hydroxynorephedrine]]}}, {{nowrap|[[4-hydroxyphenylacetone]]}}, [[benzoic acid]], [[hippuric acid]], [[norephedrine]], and [[phenylacetone]], the metabolites of amphetamine.<ref name="FDA Pharmacokinetics" /><ref name="DB Pharmacology" /><ref name="Pubchem Kinetics">{{cite encyclopedia | title=Amphetamine | url=http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=3007 | work=Pubchem Compound | publisher = National Center for Biotechnology Information | accessdate=12 October 2013 }}</ref><ref name="Metabolites">{{cite journal | author = Santagati NA, Ferrara G, Marrazzo A, Ronsisvalle G | title = Simultaneous determination of amphetamine and one of its metabolites by HPLC with electrochemical detection | journal = J. Pharm. Biomed. Anal. | volume = 30 | issue = 2 | pages = 247–255 |date=September 2002 | pmid = 12191709 | doi =10.1016/S0731-7085(02)00330-8 }}</ref>  Among these metabolites, the active [[sympathomimetics]] are amphetamine, {{nowrap|4‑hydroxyamphetamine}},<ref>{{cite encyclopedia | title=p-Hydroxyamphetamine | section-url=http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=3651 | work=PubChem Compound | publisher = National Center for Biotechnology Information | accessdate=15 October 2013 | section=Compound Summary }}</ref> {{nowrap|4‑hydroxynorephedrine}},<ref>{{cite encyclopedia | title=p-Hydroxynorephedrine | section-url=http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=11099 | work=PubChem Compound | publisher = National Center for Biotechnology Information | accessdate=15 October 2013 | section=Compound Summary }}</ref> {{nowrap|4-hydroxymethamphetamine}},<ref name="DB Pharmacology" /> and norephedrine.<ref>{{cite encyclopedia | title=Phenylpropanolamine | section-url=http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=26934 | work=PubChem Compound | publisher = National Center for Biotechnology Information | accessdate=15 October 2013 | section=Compound Summary }}</ref>
 
The main metabolic pathways involve aromatic para-hydroxylation, aliphatic alpha- and beta-hydroxylation, N-oxidation, N-dealkylation, and deamination.<ref name="FDA Pharmacokinetics" /><ref name="DB Pharmacology" /><ref name="Pubchem Kinetics" />  The known metabolic pathways include:<ref name="FDA Pharmacokinetics">{{cite web | title = Adderall XR Prescribing Information | url = http://www.accessdata.fda.gov/drugsatfda_docs/label/2013/021303s026lbl.pdf | pages = 12–13 | work = United States Food and Drug Administration |date=December 2013 | accessdate = 30 December 2013 }}</ref><ref name="DB Pharmacology" /><ref name="Metabolites" />{{Methamphetamine pharmacokinetics|caption=The primary metabolites of methamphetamine are amphetamine and 4-hydroxymethamphetamine.<ref name="DB Pharmacology" />}}
{{clear}}
 
==== Detection in biological fluids ====
 
Methamphetamine and amphetamine are often measured in urine or blood as part of a [[drug test]] for sports, employment, poisoning diagnostics, and forensics.<ref name="Ergogenics">{{cite journal | author = Liddle DG, Connor DJ | title = Nutritional supplements and ergogenic AIDS | journal = Prim. Care | volume = 40 | issue = 2 | pages = 487–505 |date=June 2013 | pmid = 23668655 | doi = 10.1016/j.pop.2013.02.009}}</ref><ref name="pmid9700558">{{cite journal | author = Kraemer T, Maurer HH | title = Determination of amphetamine, methamphetamine and amphetamine-derived designer drugs or medicaments in blood and urine | journal = J. Chromatogr. B Biomed. Sci. Appl. | volume = 713 | issue = 1 | pages = 163–187 |date=August 1998 | pmid = 9700558 | doi = 10.1016/S0378-4347(97)00515-X }}</ref><ref name="pmid17468860">{{cite journal | author = Kraemer T, Paul LD | title = Bioanalytical procedures for determination of drugs of abuse in blood | journal = Anal. Bioanal. Chem. | volume = 388 | issue = 7 | pages = 1415–1435 |date=August 2007 | pmid = 17468860 | doi = 10.1007/s00216-007-1271-6 }}</ref><ref name="pmid8075776">{{cite journal | author = Goldberger BA, Cone EJ | title = Confirmatory tests for drugs in the workplace by gas chromatography-mass spectrometry | journal = J. Chromatogr. A | volume = 674 | issue = 1–2 | pages = 73–86 |date=July 1994 | pmid = 8075776 | doi = 10.1016/0021-9673(94)85218-9 }}</ref> Chiral techniques may be employed to help distinguish the source the drug to determine whether it was obtained illicitly or legally via prescription or prodrug.<ref name="pmid15516295" /> Chiral separation is needed to assess the possible contribution of levomethamphetamine (e.g., Vicks Vapoinhaler) toward a positive test result.<ref name="pmid15516295">{{cite journal | author = Paul BD, Jemionek J, Lesser D, Jacobs A, Searles DA | title = Enantiomeric separation and quantitation of (+/-)-amphetamine, (+/-)-methamphetamine, (+/-)-MDA, (+/-)-MDMA, and (+/-)-MDEA in urine specimens by GC-EI-MS after derivatization with (R)-(−)- or (S)-(+)-alpha-methoxy-alpha-(trifluoromethy)phenylacetyl chloride (MTPA) | journal = J Anal Toxicol | volume = 28 | issue = 6 | pages = 449–455 |date=September 2004 | pmid = 15516295 | doi =10.1093/jat/28.6.449 }}</ref><ref name="pmid14871155">{{cite journal | author = de la Torre R, Farré M, Navarro M, Pacifici R, Zuccaro P, Pichini S | title = Clinical pharmacokinetics of amfetamine and related substances: monitoring in conventional and non-conventional matrices | journal = Clin Pharmacokinet | volume = 43 | issue = 3 | pages = 157–185 | year = 2004 | pmid = 14871155 | doi = 10.2165/00003088-200443030-00002  }}</ref><ref>{{cite book  | author = Baselt RC  | title = Disposition of toxic drugs and chemicals in man | year = 2011 | publisher = Biomedical Publications | location = Seal Beach, Ca. | isbn = 0-9626523-8-5 | pages = 1027–1030 }}</ref> Dietary zinc supplements can mask the presence of methamphetamine and other drugs in urine.<ref name="pmid21740689">{{cite journal | author = Venkatratnam A, Lents NH | title = Zinc reduces the detection of cocaine, methamphetamine, and THC by ELISA urine testing | journal = J. Anal. Toxicol | volume = 35 | issue = 6 | pages = 333–340 |date=July 2011 | pmid = 21740689 | doi =10.1093/anatox/35.6.333 }}</ref>
 
== Physical and chemical properties ==
[[File:Crystal Meth.jpg|thumb|Pure shards of methamphetamine hydrochloride, also known as crystal meth|alt=Methamphetamine hydrochloride]]
Methamphetamine is a [[chirality (chemistry)|chiral]] compound with two enantiomers, dextromethamphetamine and levomethamphetamine. At room temperature, the [[free base]] of methamphetamine is a clear and colorless liquid with an odor characteristic of [[geranium]] leaves.<ref name="Pubchem2" /> It is soluble in [[diethyl ether]] and [[ethanol]] as well as [[miscible]] with [[chloroform]].<ref name="Pubchem2" /> In contrast, the methampetamine hydrochloride salt is odorless with a bitter taste.<ref name="Pubchem2" /> It has a melting point between {{convert|170|to|175|C|F}} and, at room temperature, occurs as white crystals or a white [[Crystallinity|crystalline]] powder.<ref name="Pubchem2" /> The hydrochloride salt is also freely soluble in ethanol and water.<ref name="Pubchem2" />
 
=== Synthesis ===
{{Details3|[[History and culture of substituted amphetamines#Illegal synthesis|Illegal synthesis of substituted amphetamines]]|illicit amphetamine synthesis}}
[[Racemic]] methamphetamine may be prepared starting from [[phenylacetone]] by either the [[Leuckart reaction|Leuckart]]<ref name=Crossley_1944>{{cite journal | author = Crossley FS, Moore ML |title = Studies on the Leuckart reaction | journal = The Journal of Organic Chemistry |date=November 1944 | volume = 9 | issue = 6 | pages = 529–536 | doi = 10.1021/jo01188a006 }}</ref> or [[reductive amination]] methods.<ref name="pmid19637924">{{cite journal | author = Kunalan V, Nic Daéid N, Kerr WJ, Buchanan HA, McPherson AR | title = Characterization of route specific impurities found in methamphetamine synthesized by the Leuckart and reductive amination methods | journal = Anal. Chem. | volume = 81 | issue = 17 | pages = 7342–7348 |date=September 2009 | pmid = 19637924 | pmc = 3662403 | doi = 10.1021/ac9005588 }}</ref> In the Leuckart reaction, one equivalent of phenylacetone is reacted with two equivalents of {{nowrap|[[N-methylformamide|''N''-methylformamide]]}} to produce the formyl [[amide]] of methamphetamine plus carbon dioxide and [[methylamine]] as side products.<ref name="pmid19637924"/>  In this reaction, an [[iminium]] cation is formed as an intermediate which is [[Redox|reduced]] by the second equivalent of {{nowrap|''N''-methylformamide}}.<ref name="pmid19637924"/> The intermediate formyl amide is then [[hydrolyzed]] under acidic aqueous conditions to yield methamphetamine as the final product.<ref name="pmid19637924"/>  Alternatively, phenylacetone can be reacted with methylamine under reducing conditions to yield methamphetamine.<ref name="pmid19637924"/>
 
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===Degradation===
Bleach exposure time and concentration are correlated with destruction of methamphetamine.<ref>{{cite web|author=Nakayama, MT|title=Chemical Interaction of Bleach and Methamphetamine: A Study of Degradation and Transformation Effects|url=http://gradworks.umi.com/14/93/1493688.html|website=gradworks|publisher=UNIVERSITY OF CALIFORNIA, DAVIS|accessdate=17 October 2014}}</ref>  Methamphetamine in soils has shown to be a persistent pollutant.<ref name="pmid21777940">{{cite journal | author = Pal R, Megharaj M, Kirkbride KP, Heinrich T, Naidu R | title = Biotic and abiotic degradation of illicit drugs, their precursor, and by-products in soil | journal = Chemosphere | volume = 85 | issue = 6 | pages = 1002–9 |date=October 2011  | pmid = 21777940 | doi = 10.1016/j.chemosphere.2011.06.102 | url = }}</ref>  Methamphetamine is largely degraded within 30 days in a study of bioreactors under exposure to light in [[wastewater]].<ref name="pmid23886544">{{cite journal | author = Bagnall J, Malia L, Lubben A, Kasprzyk-Hordern B | title = Stereoselective biodegradation of amphetamine and methamphetamine in river microcosms | journal = Water Res. | volume = 47 | issue = 15 | pages = 5708–18 |date=October 2013  | pmid = 23886544 | doi = 10.1016/j.watres.2013.06.057 | url = }}</ref>
 
== History, society, and culture ==
{{Main|History and culture of substituted amphetamines}}
{{multiple image
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| alt2      = An advertisement for pharmaceutical methamphetamine
| caption2  = A 1970 advertisement for [[Obetrol]], a pharmaceutical mixture of amphetamine and methamphetamine salts
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Amphetamine, discovered before methamphetamine, was first synthesized in 1887 in Germany by Romanian chemist [[Lazăr Edeleanu]] who named it ''phenylisopropylamine''.<ref>{{cite book | author = Rassool GH | title=Alcohol and Drug Misuse: A Handbook for Students and Health Professionals | year=2009 | publisher=Routledge | location=London | isbn=978-0-203-87117-1 | page=113}}</ref><ref name="Vermont">{{cite web | url=http://healthvermont.gov/adap/meth/brief_history.aspx | title=Historical overview of methamphetamine | work=Vermont Department of Health | publisher=Government of Vermont | accessdate=29 January 2012}}</ref> Shortly after, methamphetamine was synthesized from [[ephedrine]] in 1893 by Japanese [[chemist]] [[Nagai Nagayoshi]].<ref name="Grobler et al 2011">{{cite journal |doi=10.5402/2011/974768 |title=The pH Levels of Different Methamphetamine Drug Samples on the Street Market in Cape Town |year=2011 |last1=Grobler |first1=Sias R. |last2=Chikte |first2=Usuf |last3=Westraat |first3=Jaco |journal=ISRN Dentistry |volume=2011 |pages=1–4 |pmid=21991491 |pmc=3189445}}</ref>  Three decades later, in 1919, methamphetamine hydrochloride was synthesized by pharmacologist [[Akira Ogata]] via [[redox|reduction]] of ephedrine using red [[phosphorus]] and [[iodine]].<ref name="history">{{cite web|url=http://healthvermont.gov/adap/meth/brief_history.aspx |title=Historical overview of methamphetamine|publisher= Vermont Department of Health |accessdate=January 2012}}</ref>
 
During World War II, ''Pervitin'' (methamphetamine) developed by Berlin based [[Temmler]] pharmaceutical company was used extensively by all branches of the [[Wehrmacht|German armed forces]] ([[Luftwaffe]] pilots, in particular) for its performance enhancing stimulant effects and to induce extended [[wakefulness]].<ref>{{cite web|title=The Nazi Death Machine: Hitler's Drugged Soldiers|url=http://www.spiegel.de/international/the-nazi-death-machine-hitler-s-drugged-soldiers-a-354606.html|publisher=Der Spiegel, 6 May 2005}}</ref><ref name="pmid22849208">{{cite journal | author = Defalque RJ, Wright AJ | title = Methamphetamine for Hitler's Germany: 1937 to 1945 | journal = Bull. Anesth. Hist. | volume = 29 | issue = 2 | pages = 21–24, 32 |date=April 2011 | pmid = 22849208 | doi =  }}</ref> ''Pervitin'' became colloquially known among the German troops as "[[Tank]]-Chocolates" (''Panzerschokolade''), "[[Stuka]]-Tablets" (''Stuka-Tabletten'') and "[[Hermann Göring|Herman-Göring]]-Pills" (''Hermann-Göring-Pillen'').
 
[[Obetrol]], patented by Obetrol Pharmaceuticals in the 1950s and indicated for treatment of [[obesity]], was one of the first brands of pharmaceutical methamphetamine products.<ref name="Real_Obetrol_Ad">{{cite book| first=Nicolas | last=Rasmussen |authorlink= | title=On Speed: The Many Lives of Amphetamine | date=March 2008 | publisher=New York University Press | edition=1|isbn= 0-8147-7601-9 | page =148}}</ref> Due to the psychological and stimulant effects of methamphetamine, Obetrol became a popular diet pill in America in the 1950s and 1960s.<ref name="Real_Obetrol_Ad" /> Eventually, as the addictive properties of the drug became known, governments began to strictly regulate the production and distribution of methamphetamine.<ref name="Vermont" />  For example, during the early 1970s in the United States, methamphetamine became a [[Schedule II (US)|schedule II controlled substance]] under the [[Controlled Substances Act]].<ref>{{cite web | title=Controlled Substances Act | url=http://www.fda.gov/regulatoryinformation/legislation/ucm148726.htm | work=United States Food and Drug Administration | date=11 June 2009 | accessdate=4 November 2013}}</ref> Currently, methamphetamine is sold under the trade name ''Desoxyn'', [[trademark]]ed by the Danish pharmaceutical company [[Lundbeck]].<ref name="Desoxyn (Lundbeck)">{{cite web|url=http://www.lundbeck.com/us/products/cns-products/desoxyn|title=Desoxyn| publisher=Lundbeck: Desoxyn| accessdate=December 2012}}</ref> As of January 2013, the Desoxyn trademark had been sold to Italian pharmaceutical company [[Recordati]].<ref>{{cite web| url=http://www.recordatirarediseases.com/products/us-product/desoxyn%C2%AE-cii-methamphetamine-hydrochloride-tablets-usp| title=Recordati: Desoxyn| publisher=Recordati SP| accessdate=May 2013}}</ref>
 
=== Present legal status ===
{{Main|Legal status of methamphetamine}}
The production, distribution, sale, and possession of methamphetamine is restricted or illegal in many [[jurisdiction]]s.<ref>{{cite book | author = United Nations Office on Drugs and Crime | title = Preventing Amphetamine-type Stimulant Use Among Young People: A Policy and Programming Guide  | publisher = United Nations | location = New York | year = 2007 | isbn = 978-92-1-148223-2 | url = http://www.unodc.org/pdf/youthnet/ATS.pdf | accessdate = 11 November 2013}}</ref><ref name="incb">{{cite web | title = List of psychotropic substances under international control | work = International Narcotics Control Board | publisher = United Nations | url = http://www.incb.org/pdf/e/list/green.pdf | accessdate = 19 November 2005 | archiveurl = http://web.archive.org/web/20051205125434/http://www.incb.org/pdf/e/list/green.pdf | archivedate= 5 December 2005 |date=August 2003}}</ref> Methamphetamine has been placed in schedule II of the [[United Nations]] [[Convention on Psychotropic Substances]] treaty.<ref name=incb />
 
== See also ==
* [[Amphetamine]]
* ''[[Breaking Bad]]'' – A television series involving the criminal production of methamphetamine
* [[Faces of Meth]]
* [[Levomethamphetamine]]
* [[Methamphetamine in the United States]]
* [[Montana Meth Project]]
* [[Phenelzine]]
* [[Rolling meth lab]]
* [[Ya ba]]
 
== References ==
{{Reflist|2}}
 
{{TAAR ligands}}
{{Phenethylamines}}
 
[[Category:Methamphetamine| ]]
[[Category:Amphetamine]]
[[Category:Anorectics]]
[[Category:Cardiac stimulants]]
[[Category:Euphoriants]]
[[Category:Japanese inventions]]
[[Category:Management of obesity]]
[[Category:Norepinephrine-dopamine releasing agents]]
[[Category:Phenethylamines]]
[[Category:Sigma agonists]]
[[Category:Stimulants]]
[[Category:Substituted amphetamines]]
[[Category:Sympathomimetics]]
[[Category:TAAR1 agonists]]
[[Category:Treatment and management of attention deficit hyperactivity disorder]]
[[Category:VMAT inhibitors]]
[[Category:Drug]]

Revision as of 12:46, 13 April 2015

Template:Pp-move-indef

Methamphetamine
An image of the methamphetamine compound
Ball-and-stick model of the methamphetamine molecule
Clinical data
Trade namesDesoxyn
SynonymsN-methylamphetamine, desoxyephedrine
AHFS/Drugs.comMonograph
[[Regulation of therapeutic goods |Template:Engvar data]]
Pregnancy
category
  • US: C (Risk not ruled out)
Dependence
liability
Physical: none
Psychological: high
Addiction
liability
Very high
Routes of
administration
Medical: oral
Recreational: oral, intravenous, insufflation, inhalation, suppository
ATC code
Legal status
Legal status
Pharmacokinetic data
BioavailabilityOral: Varies widely[6]
Rectal: 99%
IV: 100%
Protein bindingVaries widely[6]
MetabolismCYP2D6,[1] DBH,[2] FMO3,[3] XM-ligase,[4] and ACGNAT[5]
Elimination half-life9–12 hours[7]
ExcretionRenal
Identifiers
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
E number{{#property:P628}}
ECHA InfoCard{{#property:P2566}}Lua error in Module:EditAtWikidata at line 36: attempt to index field 'wikibase' (a nil value).
Chemical and physical data
FormulaC10H15N
Molar mass149.2337 g/mol
3D model (JSmol)
Melting point3 °C (37.4 °F) [8]
Boiling point212 °C (413.6 °F) [9] at 760 MM HG
  (verify)

Methamphetamine[note 1] ( /ˌmɛθæmˈfɛtəmn/; contracted from N-methyl-alpha-methylphenethylamine) is a potent central nervous system (CNS) stimulant of the phenethylamine and amphetamine classes that is used as a recreational drug and, rarely, to treat attention deficit hyperactivity disorder (ADHD) and obesity. Methamphetamine exists as two enantiomers, dextrorotary and levorotary.[note 2] Dextromethamphetamine is a stronger CNS stimulant than levomethamphetamine; however, both are neurotoxic, addictive and produce the same toxicity symptoms at high doses. Although rarely prescribed due to the potential risks, methamphetamine hydrochloride is approved by the United States Food and Drug Administration (USFDA) under the trade name Desoxyn. Recreationally, methamphetamine is used to increase sexual desire, lift the mood, and increase energy, allowing some users to engage in sexual activity continuously for several days straight.

Methamphetamine may be sold illegally, either as pure dextromethamphetamine or in an equal parts mixture of the right and left-handed molecules (i.e., 50% levomethamphetamine and 50% dextromethamphetamine). Both dextromethamphetamine and racemic methamphetamine are schedule II controlled substances in the United States. Similarly, the production, distribution, sale, and possession of methamphetamine is restricted or illegal in many other countries due to its placement in schedule II of the United Nations Convention on Psychotropic Substances treaty. In contrast, levomethamphetamine is an over-the-counter drug in the United States.[note 3]

In low doses, methamphetamine can cause an elevated mood and increase alertness, concentration, and energy in fatigued individuals. At higher doses, it can induce psychosis, rhabdomyolysis and cerebral hemorrhage. Methamphetamine is known to have a high potential for abuse and addiction. Heavy recreational use of methamphetamine may result in psychosis or lead to post-acute-withdrawal syndrome, a withdrawal syndrome that can persist for months beyond the typical withdrawal period.[i] Unlike amphetamine, methamphetamine is neurotoxic to humans, damaging both dopamine and serotonin neurons in the CNS.[i] Contrary to the long-term use of amphetamine,[iii] there is evidence that methamphetamine causes brain damage from long-term use in humans;[ii] this damage includes adverse changes in brain structure and function, such as reductions in gray matter volume in several brain regions and adverse changes in markers of metabolic integrity.[ii]

Uses

Medical

In the United States, methamphetamine hydrochloride, under the trade name Desoxyn, has been approved by the FDA for treating ADHD and exogenous obesity (obesity originating from factors outside the patient's control) in both adults and children;[14][15] however, the FDA also indicates that the limited therapeutic usefulness of methamphetamine should be weighed against the inherent risks associated with its use.[14] Methamphetamine is sometimes prescribed off label for narcolepsy and idiopathic hypersomnia.[16][17] In the United States, methamphetamine's levorotary form is available in some over-the-counter nasal decongestant products, such as Vicks VapoInhaler.[note 3]

As methamphetamine is associated with a high potential for misuse, the drug is regulated under the Controlled Substances Act and is listed under schedule II in the United States.[14] Methamphetamine hydrochloride dispensed in the United States is required to include the following boxed warning:[14]

Methamphetamine has a high potential for abuse. It should thus be tried only in weight reduction programs for patients in whom alternative therapy has been ineffective. Administration of methamphetamine for prolonged periods of time in obesity may lead to drug dependence and must be avoided. Particular attention should be paid to the possibility of subjects obtaining methamphetamine for non-therapeutic use or distribution to others, and the drug should be prescribed or dispensed sparingly. Misuse of methamphetamine may cause sudden death and serious cardiovascular adverse effects.

Recreational

Methamphetamine is often used recreationally for its effects as a potent euphoriant and stimulant as well as aphrodisiac qualities.[20] According to a National Geographic TV documentary on methamphetamine, "an entire subculture known as party and play is based around methamphetamine use".[20] Members of this San Francisco sub-culture, which consists almost entirely of gay male methamphetamine users, will typically meet up through internet dating sites and have sex.[20] Due to its strong stimulant and aphrodisiac effects and inhibitory effect on ejaculation, with repeated use, these sexual encounters will sometimes occur continuously for several days.[20] The crash following the use of methamphetamine in this manner is very often severe, with marked hypersomnia.[20]

Desoxyn tablet
Desoxyn tablets – pharmaceutical methamphetamine hydrochloride
Crystal meth
Crystal meth – illicit methamphetamine hydrochloride

Contraindications

Methamphetamine is contraindicated in individuals with a history of substance use disorder, heart disease, or severe agitation or anxiety, or in individuals currently experiencing arteriosclerosis, glaucoma, hyperthyroidism, or severe hypertension.[14] The USFDA states that individuals who have experienced hypersensitivity reactions to other stimulants in the past or are currently taking monoamine oxidase inhibitors should not take methamphetamine.[14] The USFDA also advises individuals with bipolar disorder, depression, elevated blood pressure, liver or kidney problems, mania, psychosis, Raynaud's phenomenon, seizures, thyroid problems, tics, or Tourette syndrome to monitor their symptoms while taking methamphetamine.[14] Due to the potential for stunted growth, the USFDA advises monitoring the height and weight of growing children and adolescents during treatment.[14]

Side effects

Physical

The physical effects of methamphetamine can include loss of appetite, hyperactivity, dilated pupils, flushed skin, excessive sweating, increased movement, dry mouth and teeth grinding (leading to "meth mouth"), headache, irregular heartbeat (usually as accelerated heartbeat or slowed heartbeat), rapid breathing, high blood pressure, low blood pressure, high body temperature, diarrhea, constipation, blurred vision, dizziness, twitching, numbness, tremors, dry skin, acne, and pale appearance.[14][21] Methamphetamine that is present in a mother's bloodstream can pass through the placenta to a fetus and is or be secreted into breast milk.[22] Infants born to methamphetamine-abusing mothers were found to have a significantly smaller gestational age-adjusted head circumference and birth weight measurements.[22] Methamphetamine exposure was also associated with neonatal withdrawal symptoms of agitation, vomiting and fast breathing.[22] This withdrawal syndrome is relatively mild and only requires medical intervention in approximately 4% of cases.[23]

Meth mouth

Methamphetamine users and addicts may lose their teeth abnormally quickly, regardless of the route of administration, from a condition informally known as meth mouth.[24] The condition is generally most severe in users who inject the drug, rather than those who smoke, ingest, or inhale it.[24] According to the American Dental Association, meth mouth "is probably caused by a combination of drug-induced psychological and physiological changes resulting in xerostomia (dry mouth), extended periods of poor oral hygiene, frequent consumption of high-calorie, carbonated beverages and bruxism (teeth grinding and clenching)".[24][25] Many researchers suggest that methamphetamine-induced tooth decay is due to users' lifestyles, as dry mouth is also a side effect of other stimulants, which are not known to cause serious tooth decay. They suggest that the side effect has been exaggerated and stylized to deter potential users and stereotype current users.[26]

Psychological

The psychological effects of methamphetamine can include euphoria, dysphoria, changes in libido, alertness, apprehension, concentration, decreased sense of fatigue, insomnia or wakefulness, self-confidence, sociability, irritability, restlessness, grandiosity and repetitive and obsessive behaviors.[14][21][27] Methamphetamine use also has a high association with anxiety, depression, methamphetamine psychosis, suicide, and violent behaviors.[28] Methamphetamine also has a very high addiction risk.[14]

Dependence, addiction, and withdrawal

Signaling cascade in the nucleus accumbens that results in psychostimulant addiction
This diagram depicts the signaling events in the brain's reward center that are induced by chronic high-dose exposure to psychostimulants that increase the concentration of synaptic dopamine, like amphetamine, methamphetamine, and phenethylamine. Following presynaptic dopamine and glutamate co-release by such psychostimulants,[29][30] postsynaptic receptors for these neurotransmitters trigger internal signaling events through a cAMP-dependent pathway and a calcium-dependent pathway that ultimately result in increased CREB phosphorylation.[29][31][32] Phosphorylated CREB increases levels of ΔFosB, which in turn represses the c-Fos gene with the help of corepressors;[29][33][34] c-Fos repression acts as a molecular switch that enables the accumulation of ΔFosB in the neuron.[35] A highly stable (phosphorylated) form of ΔFosB, one that persists in neurons for 1–2 months, slowly accumulates following repeated high-dose exposure to stimulants through this process.[33][34] ΔFosB functions as "one of the master control proteins" that produces addiction-related structural changes in the brain, and upon sufficient accumulation, with the help of its downstream targets (e.g., nuclear factor kappa B), it induces an addictive state.[33][34]

Tolerance is expected to develop with regular methamphetamine use and, when abused, this tolerance develops rapidly.[36][37]

The evidence on effective treatments for amphetamine and methamphetamine dependence and abuse is limited.[38] In light of this, fluoxetine[note 4] and imipramine[note 5] appear to have some limited benefits in treating abuse and addiction, "no treatment has been demonstrated to be effective for the treatment of [methamphetamine] dependence and abuse".[38]

In highly dependent amphetamine and methamphetamine abusers, "when chronic heavy users abruptly discontinue [methamphetamine] use, many report a time-limited withdrawal syndrome that occurs within 24 hours of their last dose".[39] Withdrawal symptoms in chronic, high-dose users are frequent, occurring in up to 87.6% of cases, and persist for three to four weeks with a marked "crash" phase occurring during the first week.[39] Methamphetamine withdrawal symptoms can include anxiety, drug craving, dysphoric mood, fatigue, increased appetite, increased movement or decreased movement, lack of motivation, sleeplessness or sleepiness, and vivid or lucid dreams.[39] Withdrawal symptoms are associated with the degree of dependence (i.e., the extent of abuse).[39] The mental depression associated with methamphetamine withdrawal lasts longer and is more severe than that of cocaine withdrawal.[23]

Current models of addiction from chronic drug use involve alterations in gene expression in certain parts of the brain.[40][41] The most important transcription factors that produce these alterations are ΔFosB, cyclic adenosine monophosphate (cAMP) response element binding protein (CREB), and nuclear factor kappa B (NFκB).[41] ΔFosB is the most significant, since its overexpression in the nucleus accumbens is necessary and sufficient for many of the neural adaptations seen in drug addiction;[41] it has been implicated in addictions to alcohol, cannabinoids, cocaine, nicotine, phencyclidine, and substituted amphetamines.[40][41][42] ΔJunD is the transcription factor which directly opposes ΔFosB.[41] Increases in nucleus accumbens ΔJunD expression can reduce or, with a large increase, even block most of the neural alterations seen in chronic drug abuse (i.e., the alterations mediated by ΔFosB).[41] ΔFosB also plays an important role in regulating behavioral responses to natural rewards, such as palatable food, sex, and exercise.[41][43] Since natural rewards, like drugs of abuse, induce ΔFosB, chronic acquisition of these rewards can result in a similar pathological addictive state.[41][43] Consequently, ΔFosB is the key transcription factor involved in methamphetamine addiction, especially methamphetamine-induced sex addictions.[41][43][44] ΔFosB inhibitors (drugs that oppose its action) may be an effective treatment for addiction and addictive disorders.[45]


Neurotoxicity

Unlike amphetamine, methamphetamine is directly neurotoxic to dopamine neurons.[46] Moreover, methamphetamine abuse is associated with an increased risk of Parkinson's disease due to excessive pre-synaptic dopamine autoxidation, a mechanism of neurotoxicity.[47][48][49][50] Similar to the neurotoxic effects on the dopamine system, methamphetamine can also result in neurotoxicity to serotonin neurons.[51] It has been demonstrated that a high core temperature is correlated with an increase in the neurotoxic effects of methamphetamine.[52] As a result of methamphetamine-induced neurotoxicity to dopamine neurons, chronic use may also lead to Post-acute-withdrawals which persist beyond the withdrawal period for months, and even up to a year.[47]

Sexually transmitted infection

Methamphetamine use was found to be related to higher frequencies of unprotected sexual intercourse in both HIV-positive and unknown casual partners, an association more pronounced in HIV-positive participants.[53] These findings suggest that methamphetamine use and engagement in unprotected anal intercourse are co-occurring risk behaviors, behaviors that potentially heighten the risk of HIV transmission among gay and bisexual men.[53] Methamphetamine use allows users of both sexes to engage in prolonged sexual activity, which may cause genital sores and abrasions as well as priapism in men.[14][54] Methamphetamine may also cause sores and abrasions in the mouth via bruxism, increasing the risk of sexually transmitted infection.[14][54]

Besides the sexual transmission of HIV, it may also be transmitted between users who share a common needle.[55] The level of needle sharing among methamphetamine users is similar to that among other drug injection users.[55]

Overdose

A methamphetamine overdose may result in a wide range of symptoms.[7][14] A moderate overdose of methamphetamine may induce symptoms such as: abnormal heart rhythm, confusion, difficult and/or painful urination, high or low blood pressure, high body temperature, over-active and/or over-responsive reflexes, muscle aches, severe agitation, rapid breathing, tremor, urinary hesitancy, and an inability to pass urine.[7][21] An extremely large overdose may produce symptoms such as adrenergic storm, methamphetamine psychosis, substantially reduced or nil urine output, cardiogenic shock, brain bleed, circulatory collapse, dangerously high body temperature, pulmonary hypertension, kidney failure, rhabdomyolysis, serotonin syndrome, and a form of stereotypy ("tweaking").[Refnote 1] A methamphetamine overdose will likely also result in mild brain damage due to dopaminergic and serotonergic neurotoxicity.[46][51] Death from methamphetamine poisoning is typically preceded by convulsions and coma.[14]

Emergency treatment

The USFDA states[note 6] that acute methamphetamine intoxication is largely managed by treating the symptoms and includes may initially include administration of activated charcoal and sedation.[7] There is not enough evidence on hemodialysis or peritoneal dialysis in cases of methamphetamine intoxication to determine their usefulness.[14] Forced acid diuresis (e.g., with vitamin C) will increase methamphetamine excretion but is not recommended as it may increase the risk of aggravating acidosis, or cause seizures or rhabdomyolysis.[7] Hypertension presents a risk for intracranial hemorrhage and, if severe, is typically treated with intravenous phentolamine or nitroprusside.[7] Blood pressure often drops gradually following sufficient sedation with a benzodiazepine and providing a calming environment.[7] Chlorpromazine may be useful in decreasing the stimulant and CNS effects of a methamphetamine overdose.[14] The use of a nonselective beta blocker may be required to control increased heart rate.[7]

Psychosis

Template:Main section

Abuse of methamphetamine can result in a stimulant psychosis which may present with a variety of symptoms (e.g. paranoia, hallucinations, delirium, delusions).[7][59] A Cochrane Collaboration review on treatment for amphetamine, dextroamphetamine, and methamphetamine abuse-induced psychosis states that about 5–15% of users fail to recover completely.[59][60] The same review asserts that, based upon at least one trial, antipsychotic medications effectively resolve the symptoms of acute amphetamine psychosis.[59] Methamphetamine psychosis may also develop occasionally as a treatment-emergent side effect.[61]

Interactions

Methamphetamine is metabolized by the liver enzyme CYP2D6, so CYP2D6 inhibitors (e.g., selective serotonin reuptake inhibitors (SSRIs)) will prolong the elimination half-life of methamphetamine.[62] Methamphetamine also interacts with monoamine oxidase inhibitors (MAOIs), since both MAOIs and methamphetamine increase plasma catecholamines; therefore, concurrent use of both is dangerous.[14] Methamphetamine may decrease the effects of sedatives and depressants and increase the effects of antidepressants and other stimulants as well.[14] Methamphetamine may counteract the effects of antihypertensives and antipsychotics due to its effects on the cardiovascular system and cognition respectively.[14] The pH of gastrointestinal content and urine affects the absorption and excretion of methamphetamine.[14] Specifically, acidic substances will reduce the absorption of methamphetamine and increase urinary excretion, while alkaline substances do the opposite.[14] Due to the effect pH has on absorption, proton pump inhibitors, which reduce gastric acid, are known to interact with methamphetamine.[14]

Pharmacology

An image of methamphetamine pharmacodynamics
This illustration depicts the normal operation of the dopaminergic terminal to the left, and the dopaminergic terminal in presence of methamphetamine to the right. Methamphetamine reverses the action of the dopamine transporter (DAT) by activating TAAR1 (not shown). TAAR1 activation also causes some of the dopamine transporters to move into the presynaptic neuron and cease transport (not shown). At VMAT2 (labeled VMAT), methamphetamine causes dopamine efflux (release).

Amphetamines, in general, act as monoamine releasing agents and reuptake inhibitors. They inhibit VMAT-2, preventing packaging of monoamines into vesicles. As these monoamine neurotransmitters remain in the cytoplasm at an ever-climbing level, the gradient for their transporters becomes progressively less favorable, which, in combination with dopamine transporter phosphorylation caused by amphetamines, causes the transporters to work in reverse, resulting in monoamine release. There is also some evidence that amphetamines act as monoamine oxidase inhibitors, amplifying this effect by preventing degradation of these neurotransmitters.

Pharmacodynamics

Like amphetamine, methamphetamine has been identified as a potent full agonist of trace amine-associated receptor 1 (TAAR1), a G protein-coupled receptor (GPCR) that regulates brain catecholamine systems.[63][64] Activation of TAAR1, via adenylyl cyclase, increases cyclic adenosine monophosphate (cAMP) production and either completely inhibits or reverses the transport direction of the dopamine transporter (DAT), norepinephrine transporter (NET), and serotonin transporter (SERT).[63][65] When methamphetamine binds to TAAR1, it triggers transporter phosphorylation via protein kinase A (PKA) and protein kinase C (PKC) signaling, ultimately resulting in the internalization or reverse function of monoamine transporters.[63][66] Other transporters that methamphetamine is known to inhibit are vesicular monoamine transporter 1 (VMAT1), vesicular monoamine transporter 2 (VMAT2), SLC22A3, and SLC22A5.[67] SLC22A3 is an extraneuronal monoamine transporter that is present in astrocytes and SLC22A5 is a high-affinity carnitine transporter.[64][68] When methamphetamine interacts with VMAT2, it induces a release of monoamines from the synaptic vesicles (vesicles that stores monoamines) into the cytosol (intracellular fluid) of the presynaptic neuron.[69]

Methamphetamine is also an agonist of the alpha-2 adrenergic receptors and sigma receptors, and inhibits vesicular monoamine transporter 1 (VMAT1), monoamine oxidase B (MAO-B), and monoamine oxidase A (MAO-A).[64][70][71] Methamphetamine is known to inhibit the CYP2D6 liver enzyme as well.[62] Dextromethamphetamine is a stronger psychostimulant, but levomethamphetamine has a longer half-life and is CNS-active with weaker effects (approximately one-tenth) on striatal dopamine and shorter perceived effects among addicts.[72][73][74] At high doses, both enantiomers of methamphetamine can induce stereotypy and methamphetamine psychosis,[73] but levomethamphetamine is less desired by recreational drug users because of its weaker pharmacodynamic profile.[74]

Although all the mechanisms are not fully understood, methamphetamine is a known neurotoxin in both lab animals and humans.[46][51][75][76] Beyond neurotoxicity, magnetic resonance imaging studies on human methamphetamine addicts and abusers indicate adverse neuroplastic changes, such as significant abnormalities in various brain structures.[51] In particular, methamphetamine appears to cause white matter hyperintensity and hypertrophy, marked shrinkage of hippocampi, and a reduction in gray matter in the cingulate cortex, limbic cortex, and paralimbic cortex.[51] Moreover, there are adverse changes in various metabolic markers of metabolic integrity or synthesis in methamphetamine abusers, such as reductions in N-acetylaspartate and creatine as well as elevated choline and myoinositol levels.[51]

Comparison to amphetamine pharmacodynamics

Both amphetamine and methamphetamine are potent CNS stimulants with a few biomolecular targets and affected transporters in common; however, there are important pharmacodynamic differences between the two compounds.[Refnote 2] Both compounds are potent trace amine-associated receptor 1 (TAAR1) agonists (causing non-competitive inhibition of DAT, NET, and SERT) and inhibitors of VMAT2, SLC22A3, and SLC22A5.[Refnote 3] However, methamphetamine appears to bind at a different site at VMAT2 than amphetamine.[80] Methamphetamine also inhibits VMAT1, has agonist activity at all alpha-2 adrenergic receptor and sigma receptor subtypes, and is directly toxic to dopamine neurons in humans, whereas there is no evidence of acute amphetamine toxicity in humans.[46][51][64][70] Sigma receptor activity is known to potentiate the stimulant and neurotoxic effects of methamphetamine.[70][71]

In contrast to the adverse neuroplastic effects evident in methamphetamine addicts and abusers, long-term use of amphetamine or methylphenidate at therapeutic doses appears to produce beneficial changes in brain function and structure, such as normalization of the right caudate nucleus.[81][82]

Pharmacokinetics

Following oral administration, methamphetamine is well-absorbed into the bloodstream, with peak plasma methamphetamine concentrations achieved in approximately 3.13–6.3 hours post ingestion.[83] Methamphetamine is also well absorbed following inhalation and following intranasal administration.[7] Due to the high lipophilicity of methamphetamine, it can readily move through the blood–brain barrier faster than other stimulants, where it is more resistant to degradation by monoamine oxidase.[7][83] The amphetamine metabolite peaks at 10–24 hours.[7] It is excreted by the kidneys, with the rate of excretion into the urine heavily influenced by urinary pH.[14][83] When taken orally, 30–54% of the dose is excreted in urine as methamphetamine and 10–23% as amphetamine.[83] Following IV doses, about 45% is excreted as methamphetamine and 7% as amphetamine.[83] The half-life of methamphetamine is variable with a mean value of between 5 and 12 hours.[7][83]

CYP2D6, dopamine β-hydroxylase, flavin-containing monooxygenase, butyrate-CoA ligase, and glycine N-acyltransferase are the enzymes known to metabolize methamphetamine or its metabolites in humans.[2][3][4][5][62] The primary metabolites are amphetamine and 4-hydroxymethamphetamine; other minor metabolites include: 4-hydroxyamphetamine, 4-hydroxynorephedrine, 4-hydroxyphenylacetone, benzoic acid, hippuric acid, norephedrine, and phenylacetone, the metabolites of amphetamine.[1][83][84][85] Among these metabolites, the active sympathomimetics are amphetamine, 4‑hydroxyamphetamine,[86] 4‑hydroxynorephedrine,[87] 4-hydroxymethamphetamine,[83] and norephedrine.[88]

The main metabolic pathways involve aromatic para-hydroxylation, aliphatic alpha- and beta-hydroxylation, N-oxidation, N-dealkylation, and deamination.[1][83][84] The known metabolic pathways include:[1][83][85]Template:Methamphetamine pharmacokinetics

Detection in biological fluids

Methamphetamine and amphetamine are often measured in urine or blood as part of a drug test for sports, employment, poisoning diagnostics, and forensics.[89][90][91][92] Chiral techniques may be employed to help distinguish the source the drug to determine whether it was obtained illicitly or legally via prescription or prodrug.[93] Chiral separation is needed to assess the possible contribution of levomethamphetamine (e.g., Vicks Vapoinhaler) toward a positive test result.[93][94][95] Dietary zinc supplements can mask the presence of methamphetamine and other drugs in urine.[96]

Physical and chemical properties

Methamphetamine hydrochloride
Pure shards of methamphetamine hydrochloride, also known as crystal meth

Methamphetamine is a chiral compound with two enantiomers, dextromethamphetamine and levomethamphetamine. At room temperature, the free base of methamphetamine is a clear and colorless liquid with an odor characteristic of geranium leaves.[9] It is soluble in diethyl ether and ethanol as well as miscible with chloroform.[9] In contrast, the methampetamine hydrochloride salt is odorless with a bitter taste.[9] It has a melting point between 170  (Expression error: Unexpected round operator. ) and, at room temperature, occurs as white crystals or a white crystalline powder.[9] The hydrochloride salt is also freely soluble in ethanol and water.[9]

Synthesis

Template:Details3 Racemic methamphetamine may be prepared starting from phenylacetone by either the Leuckart[97] or reductive amination methods.[98] In the Leuckart reaction, one equivalent of phenylacetone is reacted with two equivalents of N-methylformamide to produce the formyl amide of methamphetamine plus carbon dioxide and methylamine as side products.[98] In this reaction, an iminium cation is formed as an intermediate which is reduced by the second equivalent of N-methylformamide.[98] The intermediate formyl amide is then hydrolyzed under acidic aqueous conditions to yield methamphetamine as the final product.[98] Alternatively, phenylacetone can be reacted with methylamine under reducing conditions to yield methamphetamine.[98]

Methamphetamine synthesis
Method of methamphetamine synthesis of methamphetamine via reductive amination

Degradation

Bleach exposure time and concentration are correlated with destruction of methamphetamine.[99] Methamphetamine in soils has shown to be a persistent pollutant.[100] Methamphetamine is largely degraded within 30 days in a study of bioreactors under exposure to light in wastewater.[101]

History, society, and culture

A Pervitin tablet container, the methamphetamine brand used by German soldiers during World War II
A 1970 advertisement for Obetrol, a pharmaceutical mixture of amphetamine and methamphetamine salts

Amphetamine, discovered before methamphetamine, was first synthesized in 1887 in Germany by Romanian chemist Lazăr Edeleanu who named it phenylisopropylamine.[102][103] Shortly after, methamphetamine was synthesized from ephedrine in 1893 by Japanese chemist Nagai Nagayoshi.[104] Three decades later, in 1919, methamphetamine hydrochloride was synthesized by pharmacologist Akira Ogata via reduction of ephedrine using red phosphorus and iodine.[105]

During World War II, Pervitin (methamphetamine) developed by Berlin based Temmler pharmaceutical company was used extensively by all branches of the German armed forces (Luftwaffe pilots, in particular) for its performance enhancing stimulant effects and to induce extended wakefulness.[106][107] Pervitin became colloquially known among the German troops as "Tank-Chocolates" (Panzerschokolade), "Stuka-Tablets" (Stuka-Tabletten) and "Herman-Göring-Pills" (Hermann-Göring-Pillen).

Obetrol, patented by Obetrol Pharmaceuticals in the 1950s and indicated for treatment of obesity, was one of the first brands of pharmaceutical methamphetamine products.[108] Due to the psychological and stimulant effects of methamphetamine, Obetrol became a popular diet pill in America in the 1950s and 1960s.[108] Eventually, as the addictive properties of the drug became known, governments began to strictly regulate the production and distribution of methamphetamine.[103] For example, during the early 1970s in the United States, methamphetamine became a schedule II controlled substance under the Controlled Substances Act.[109] Currently, methamphetamine is sold under the trade name Desoxyn, trademarked by the Danish pharmaceutical company Lundbeck.[110] As of January 2013, the Desoxyn trademark had been sold to Italian pharmaceutical company Recordati.[111]

Present legal status

The production, distribution, sale, and possession of methamphetamine is restricted or illegal in many jurisdictions.[112][113] Methamphetamine has been placed in schedule II of the United Nations Convention on Psychotropic Substances treaty.[113]

See also

References

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