*SUBCUTANEOUSLY OR INTRAMUSCULARLY: Usual dose, from 2 mg to 5 mg. Range, from 1 mg to 10 mg. Initial dose should not exceed 5 mg.
*INTRAVENOUSLY: Usual dose, 0.2 mg. Range, from 0.1 mg to 0.5 mg. Initial dose should not exceed 0.5 mg.
*Injections should not be repeated more often than every 10 to 15 minutes. A 5 mg intramuscular dose should raise blood pressure for one to two hours. A 0.5 mg intravenous dose should elevate the blood pressure for about 15 minutes.
=====Severe Hypotension and Shock - Including Drug-Related Hypotension=====
*Blood volume depletion should always be corrected as fully as possible before any vasopressor is administered. When, as an emergency measure, intraaortic pressures must be maintained to prevent cerebral or coronary artery ischemia, phenylephrine can be administered before and concurrently with blood volume replacement.
*Hypotension and occasionally severe shock may result from overdosage or idiosyncrasy following the administration of certain drugs, especially adrenergic and ganglionic blocking agents, rauwolfia and veratrum alkaloids and phenothiazine tranquilizers. Patients who receive a phenothiazine derivative as preoperative medication are especially susceptible to these reactions. As an adjunct in the management of such episodes, Phenylephrine Hydrochloride Injection is a suitable agent for restoring blood pressure.
*Higher initial and maintenance doses of phenylephrine are required in patients with persistent or untreated severe hypotension or shock. Hypotension produced by powerful peripheral adrenergic blocking agents, chlorpromazine or pheochromocytomectomy may also require more intensive therapy.
*Continuous Infusion:
:*Add 10 mg of the drug (1 mL of 1 percent solution) to 500 mL of Dextrose Injection, USP or Sodium Chloride Injection, USP (providing a 1:50,000 solution). To raise the blood pressure rapidly, start the infusion at about 100 mcg to 180 mcg per minute (based on 20 drops per mL this would be 100 to 180 drops per minute). When the blood pressure is stabilized (at a low normal level for the individual), a maintenance rate of 40 mcg to 60 mcg per minute usually suffices (based on 20 drops per mL this would be 40 to 60 drops per minute). If the drop size of the infusion system varies from the 20 drops per mL the dose must be adjusted accordingly.
:*If a prompt initial pressor response is not obtained, additional increments of phenylephrine (10 mg or more) are added to the infusion bottle. The rate of flow is then adjusted until the desired blood pressure level is obtained. (In some cases, a more potent vasopressor, such as norepinephrine bitartrate, may be required.) Hypertension should be avoided. The blood pressure should be checked frequently. Headache and/or bradycardia may indicate hypertension. Arrhythmias are rare.
===== Spinal Anesthesia-Hypotension =====
*Routine parenteral use of phenylephrine has been recommended for the prophylaxis and treatment of hypotension during spinal anesthesia. It is best administered subcutaneously or intramuscularly three or four minutes before injection of the spinal anesthetic. The total requirement for high anesthetic levels is usually 3 mg, and for lower levels, 2 mg. For hypotensive emergencies during spinal anesthesia, phenylephrine may be injected intravenously, using an initial dose of 0.2 mg. Any subsequent dose should not exceed the previous dose by more than 0.1 mg to 0.2 mg and no more than 0.5 mg should be administered in a single dose.
*To combat hypotension during spinal anesthesia in children, a dose of 0.5 mg to 1 mg per 25 pounds body weight, administered subcutaneously or intramuscularly, is recommended.
===== Prolongation of Spinal Anesthesia =====
*The addition of 2 mg to 5 mg of phenylephrine hydrochloride to the anesthetic solution increases the duration of motor block by as much as approximately 50 percent without any increase in the incidence of complications such as nausea, vomiting or blood pressure disturbances.
=====Vasoconstrictor for Regional Analgesia=====
*Concentrations about ten times those employed when epinephrine is used as a vasoconstrictor are recommended. The optimum strength is 1:20,000 (made by adding 1 mg of phenylephrine hydrochloride to every 20 mL of local anesthetic solution). Some pressor responses can be expected when 2 mg or more are injected.
=====Paroxysmal Supraventricular Tachycardia=====
*Rapid intravenous injection (within 20 to 30 seconds) is recommended. The initial dose should not exceed 0.5 mg, and subsequent doses, which are determined by the initial blood pressure response, should not exceed the preceding dose by more than 0.1 mg to 0.2 mg and should never exceed 1 mg.
*Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
=====Vasoconstriction and Pupil Dilation=====
*Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% is especially useful when rapid and powerful dilation of the pupil without cycloplegia and reduction of congestion in the capillary bed are desired. A drop of a suitable topical anesthetic may be applied, followed in a few minutes by 1 drop of Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% on the upper limbus. The anesthetic prevents stinging and consequent dilution of the solution by lacrimination. It may occasionally be necessary to repeat the instillation after one hour, again preceded by the use of the topical anesthetic.
=====Uveitis=====
*Posterior Synechiae: Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% may be used in patients with uveitis when synechiae are present or may develop. The formation of synechiae may be prevented by the use of this solution and atropine or other cycloplegics to produce wide dilation of the pupil. For recently formed posterior synechiae one drop of Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% may be applied to the upper surface of the cornea and be repeated as necessary, not to exceed three times. Treatment may be continued the following day, if necessary. Atropine sulfate and the application of hot compresses should also be used if indicated.
=====Glaucoma=====
*Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% may be used with miotics in patients with open angle glaucoma. It reduces the difficulties experienced by the patient because of the small field produced by miosis, and still it permits and often supports the effect of the miotic in lowering the intraocular pressure in open angle glaucoma. Hence, there may be marked improvement in visual acuity after using Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% in conjunction with miotic drugs.
=====Surgery=====
*When a short-acting mydriatic is needed for wide dilation of the pupil before intraocular surgery, Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% may be applied topically from 30 to 60 minutes before the operation.
=====Refraction=====
*Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% may be used effectively to increase mydriasis with homatropine hydrobromide, cyclopentolate hydrochloride, tropicamide hydrochloride and atropine sulfate.
*One drop of the preferred cycloplegic is placed in each eye, followed in 5 minutes by one drop of Phenylephrine Hydrochloride Ophthalmic Solution, 2.5%. Since adequate cycloplegia is achieved at different time intervals after the instillation of the necessary number of drops, different cycloplegics will require different waiting periods to achieve adequate cycloplegia.
<!--Off-Label Use and Dosage (Adult)-->
<!--Guideline-Supported Use (Adult)-->
|offLabelAdultGuideSupport=
=====Condition1=====
* Developed by:
* Class of Recommendation:
* Strength of Evidence:
* Dosing Information
:* Dosage
=====Condition2=====
There is limited information regarding <i>Off-Label Guideline-Supported Use</i> of {{PAGENAME}} in adult patients.
<!--Non–Guideline-Supported Use (Adult)-->
|offLabelAdultNoGuideSupport=
=====Condition1=====
* Dosing Information
:* Dosage
=====Condition2=====
There is limited information regarding <i>Off-Label Non–Guideline-Supported Use</i> of {{PAGENAME}} in adult patients.
<!--Pediatric Indications and Dosage-->
<!--FDA-Labeled Indications and Dosage (Pediatric)-->
|fdaLIADPed=
=====Condition1=====
* Dosing Information
:* Dosage
=====Condition2=====
There is limited information regarding <i>FDA-Labeled Use</i> of {{PAGENAME}} in pediatric patients.
<!--Off-Label Use and Dosage (Pediatric)-->
<!--Guideline-Supported Use (Pediatric)-->
|offLabelPedGuideSupport=
=====Condition1=====
* Developed by:
* Class of Recommendation:
* Strength of Evidence:
* Dosing Information
:* Dosage
=====Condition2=====
There is limited information regarding <i>Off-Label Guideline-Supported Use</i> of {{PAGENAME}} in pediatric patients.
<!--Non–Guideline-Supported Use (Pediatric)-->
|offLabelPedNoGuideSupport=
=====Condition1=====
* Dosing Information
:* Dosage
=====Condition2=====
There is limited information regarding <i>Off-Label Non–Guideline-Supported Use</i> of {{PAGENAME}} in pediatric patients.
<!--Contraindications-->
|contraindications=
* Phenylephrine Hydrochloride Injection should not be used in patients with severe hypertension, ventricular tachycardia or in patients who are hypersensitive to it or to any of the components.
*Ophthalmic solutions of phenylephrine HCl are contraindicated in patients with anatomically narrow angles or narrow angle glaucoma. Phenylephrine HCl may be contraindicated in low birth weight infants and in some elderly adults with severe arteriosclerotic cardiovascular or cerebrovascular disease. Phenylephrine HCl may be contraindicated during intraocular operative procedures when the corneal epithelial barrier has been disturbed. This preparation is also contraindicated in persons with a known sensitivity to phenylephrine HCl or any of its components.
<!--Warnings-->
|warnings=
*If used in conjunction with oxytocic drugs, the pressor effect of sympathomimetic pressor amines is potentiated (see PRECAUTIONS, Drug Interactions). The obstetrician should be warned that some oxytocic drugs may cause severe persistent hypertension and that even a rupture of a cerebral blood vessel may occur during the postpartum period.
*This product contains sodium metabisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people. The overall prevalence of sulfite sensitivity in the general population is unknown and probably low. Sulfite sensitivity is seen more frequently in asthmatic than in nonasthmatic people.
====Precautions====
* Phenylephrine hydrochloride should be employed only with extreme caution in elderly patients or in patients with hyperthyroidism, bradycardia, partial heart block, myocardial disease or severe arteriosclerosis.
<!--Adverse Reactions-->
<!--Clinical Trials Experience-->
|clinicalTrials=
*Headache, reflex bradycardia, excitability, restlessness and rarely arrhythmias.
=====Body as a Whole=====
=====Cardiovascular=====
=====Digestive=====
=====Endocrine=====
=====Hematologic and Lymphatic=====
=====Metabolic and Nutritional=====
=====Musculoskeletal=====
=====Neurologic=====
=====Respiratory=====
=====Skin and Hypersensitivy Reactions=====
=====Special Senses=====
=====Urogenital=====
=====Miscellaneous=====
<!--Postmarketing Experience-->
|postmarketing=
There is limited information regarding <i>Postmarketing Experience</i> of {{PAGENAME}} in the drug label.
=====Body as a Whole=====
=====Cardiovascular=====
=====Digestive=====
=====Endocrine=====
=====Hematologic and Lymphatic=====
=====Metabolic and Nutritional=====
=====Musculoskeletal=====
=====Neurologic=====
=====Respiratory=====
=====Skin and Hypersensitivy Reactions=====
=====Special Senses=====
=====Urogenital=====
=====Miscellaneous=====
<!--Drug Interactions-->
|drugInteractions=
* MAO Inhibitors
:*The pressor effect of sympathomimetic pressor amines is markedly potentiated in patients receiving monoamine oxidase inhibitors (MAOI). Therefore, when initiating pressor therapy in these patients, the initial dose should be small and used with due caution. The pressor response of adrenergic agents may also be potentiated by tricyclic antidepressants.
<!--Use in Specific Populations-->
|useInPregnancyFDA=
* '''Pregnancy Category C'''
*Animal reproduction studies have not been conducted with phenylephrine. It is also not known whether phenylephrine can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Phenylephrine should be given to a pregnant woman only if clearly needed.
|useInPregnancyAUS=
* '''Australian Drug Evaluation Committee (ADEC) Pregnancy Category'''
There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of {{PAGENAME}} in women who are pregnant.
|useInLaborDelivery=
*If vasopressor drugs are either used to correct hypotension or added to the local anesthetic solution, the obstetrician should be cautioned that some oxytocic drugs may cause severe persistent hypertension and that even a rupture of a cerebral blood vessel may occur during the postpartum period.
|useInNursing=
*It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when phenylephrine hydrochloride is administered to a nursing woman.
|useInPed=
*To combat hypotension during spinal anesthesia in children, a dose of 0.5 mg to 1 mg per 25 pounds of body weight, administered subcutaneously or intramuscularly, is recommended.
|useInGeri=
There is no FDA guidance on the use of {{PAGENAME}} with respect to geriatric patients.
|useInGender=
There is no FDA guidance on the use of {{PAGENAME}} with respect to specific gender populations.
|useInRace=
There is no FDA guidance on the use of {{PAGENAME}} with respect to specific racial populations.
|useInRenalImpair=
There is no FDA guidance on the use of {{PAGENAME}} in patients with renal impairment.
|useInHepaticImpair=
There is no FDA guidance on the use of {{PAGENAME}} in patients with hepatic impairment.
|useInReproPotential=
There is no FDA guidance on the use of {{PAGENAME}} in women of reproductive potentials and males.
|useInImmunocomp=
There is no FDA guidance one the use of {{PAGENAME}} in patients who are immunocompromised.
<!--Administration and Monitoring-->
|administration=
*Oral
*Intravenous
*Intramuscular
*Subcutaneous
|monitoring=
There is limited information regarding <i>Monitoring</i> of {{PAGENAME}} in the drug label.
<!--IV Compatibility-->
|IVCompat=
There is limited information regarding <i>IV Compatibility</i> of {{PAGENAME}} in the drug label.
<!--Overdosage-->
|overdose=
===Acute Overdose===
====Signs and Symptoms====
* Overdosage may induce ventricular extrasystole and short paroxysms of ventricular tachycardia, a sensation of fullness in the head and tingling of the extremities.
*The oral LD50 in the rat is 350 mg/kg, in the mouse 120 mg/kg.
====Management====
*Should an excessive elevation of blood pressure occur, it may be immediately relieved by an α-adrenergic blocking agent (e.g. phentolamine).
===Chronic Overdose===
There is limited information regarding <i>Chronic Overdose</i> of {{PAGENAME}} in the drug label.
<!--Pharmacology-->
<!--Drug box 2-->
|drugBox=
<!--Mechanism of Action-->
|mechAction=
* Phenylephrine hydrochloride produces vasoconstriction that lasts longer than that of epinephrine and ephedrine. Responses are more sustained than those to epinephrine, lasting 20 minutes after intravenous and as long as 50 minutes after subcutaneous injection. Its action on the heart contrasts sharply with that of epinephrine and ephedrine, in that it slows the heart rate and increases the stroke output, producing no disturbance in the rhythm of the pulse.
*Phenylephrine is a powerful postsynaptic alpha-receptor stimulant with little effect on the beta receptors of the heart. In therapeutic doses, it produces little if any stimulation of either the spinal cord or cerebrum. A singular advantage of this drug is the fact that repeated injections produce comparable effects.
<!--Structure-->
|structure=
* Phenylephrine hydrochloride is a vasoconstrictor and pressor drug chemically related to epinephrine and ephedrine. Phenylephrine hydrochloride is a synthetic sympathomimetic agent in sterile form for parenteral injection. Chemically, phenylephrine hydrochloride is (-)-m-Hydroxy-α-[(methylamino)methyl]benzyl alcohol hydrochloride, and has the following structural formula:
: [[File:{{PAGENAME}}01.png|thumb|none|600px|This image is provided by the National Library of Medicine.]]
*Each mL contains: Phenylephrine Hydrochloride 10 mg; Sodium Chloride 3.5 mg; Sodium Citrate Dihydrate 4 mg; Citric Acid Monohydrate 1 mg; Sodium Metabisulfite 2 mg; Water for Injection q.s. pH adjusted with Sodium Hydroxide and/or Hydrochloric Acid if necessary. pH 3.0-6.5.
<!--Pharmacodynamics-->
|PD=
*The predominant actions of phenylephrine are on the cardiovascular system. Parenteral administration causes a rise in systolic and diastolic pressures in man and other species. Accompanying the pressor response to phenylephrine is a marked reflex bradycardia that can be blocked by atropine; after atropine, large doses of the drug increase the heart rate only slightly. In man, cardiac output is slightly decreased and peripheral resistance is considerably increased. Circulation time is slightly prolonged, and venous pressure is slightly increased; venous constriction is not marked. Most vascular beds are constricted; renal splanchnic, cutaneous and limb blood flows are reduced but coronary blood flow is increased. Pulmonary vessels are constricted, and pulmonary arterial pressure is raised.
*The drug is a powerful vasoconstrictor with properties very similar to those of norepinephrine but almost completely lacking the chronotropic and inotropic actions on the heart. Cardiac irregularities are seen only very rarely even with large doses.
<!--Pharmacokinetics-->
|PK=
There is limited information regarding <i>Pharmacokinetics</i> of {{PAGENAME}} in the drug label.
<!--Nonclinical Toxicology-->
|nonClinToxic=
*No long-term animal studies have been done to evaluate the potential of phenylephrine in these areas.
<!--Clinical Studies-->
|clinicalStudies=
There is limited information regarding <i>Clinical Studies</i> of {{PAGENAME}} in the drug label.
<!--How Supplied-->
|howSupplied=
*Phenylephrine Hydrochloride Injection, USP 1% (10 mg/mL) is supplied as follows:
:*NDC 0641-6088-25
:*1 mL Single Dose vial packaged in 25s
*Store at 20°-25°C (68°-77°F), excursions permitted to 15°-30°C (59°-86°F). PROTECT FROM LIGHT. Keep covered in carton until time of use. FOR SINGLE USE ONLY. DISCARD UNUSED PORTION.
==Overview==
*Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% in plastic DROP-TAINER* dispensers:
:*3mL NDC 61314-342-01
:*5mL NDC 61314-342-02
'''Phenylephrine''' is a selective [[Alpha-1 adrenergic receptor|α<sub>1</sub>-adrenergic receptor]] [[agonist]] used primarily as a [[decongestant]], as an agent to dilate the [[pupil]], and to increase [[blood pressure]]. Phenylephrine is marketed as a substitute for the decongestant [[pseudoephedrine]], though clinical studies differ regarding its effectiveness in this role.
<!--Patient Counseling Information-->
==Uses==
|fdaPatientInfo=
===Decongestant===
Phenylephrine is used as a decongestant sold as an oral medicine, as a [[nasal spray]], or as eye drops. It is now the most common [[Over-the-counter drug|over-the-counter]] [[decongestant]] in the United States; [[oxymetazoline]] is a more common nasal spray.
Oral phenylephrine is extensively [[metabolism|metabolised]] by [[monoamine oxidase]],<ref name = DB>http://www.drugbank.ca/drugs/DB00388#identification</ref> an [[enzyme]] that is present in the intestinal wall and in the liver. Compared to intravenous pseudoephedrine, it has a reduced and variable [[bioavailability]]; only up to 38%.<ref name = DB/><ref>[http://www.medsafe.govt.nz/Profs/Class/mccMin25Nov2004.htm NZ Medicines and Medical Devices Safety Authority recommendation on phenylephrine] (November 2004)</ref> Because phenylephrine is a selective α-[[adrenergic receptor]] agonist it does not cause the release of endogenous [[Norepinephrine|noradrenaline]]. Nor does it increase the rate ([[chronotropy]]) and strength ([[inotropy]]) of heart contractions, as pseudoephedrine does.<ref>http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=72348406-e74f-46c5-b93d-34d07cffe1fd</ref> Phenylephrine may cause side effects such as headache, reflex bradycardia, excitability, restlessness and cardiac arrhythmias.<ref>http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=72348406-e74f-46c5-b93d-34d07cffe1fd</ref>
There is limited information regarding <i>Patient Counseling Information</i> of {{PAGENAME}} in the drug label.
Phenylephrine is used as a replacement for pseudoephedrine in decongestant medicines due to pseudoephedrine's use in the illicit manufacture of methamphetamine. Its efficacy as an oral decongestant has been questioned, with multiple studies not being able to come to an agreement. Whereas pseudoephedrine causes both vasoconstriction and increase of mucociliary clearance through its nonspecific adrenergic activity, phenylephrine's selective α-adrenergic agonism causes vasoconstriction alone, creating a difference in their methods of action.
<!--Precautions with Alcohol-->
As a nasal spray, phenylephrine is available in 1% and 0.5% concentrations. It may cause [[rhinitis medicamentosa|rebound congestion]], similar to oxymetazoline.
|alcohol=
===Hemorrhoid discomfort===
* Alcohol-{{PAGENAME}} interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.
This medication is used to temporarily relieve swelling, burning, pain, and itching caused by hemorrhoids. It works by temporarily narrowing the blood vessels in the area. This effect decreases swelling and discomfort. Some products may also contain substances (e.g., cocoa butter, hard fat, mineral oil, shark liver oil) that form a protective barrier to prevent too much irritating contact with stool.<ref>http://www.webmd.com/drugs/drug-76444-phenylephrine+HCl+Rect.aspx?drugid=76444&drugname=phenylephrine+HCl+Rect</ref>
===Mydriatic===
<!--Brand Names-->
Phenylephrine is used as an eye drop to dilate the pupil to facilitate visualization of the retina. It is often used in combination with [[tropicamide]] as a synergist when tropicamide alone is not sufficient. Narrow-angle [[glaucoma]] is a [[contraindication]] to phenylephrine use. As a [[mydriasis|mydriatic]], it is available in 2.5% and 10% minims.
===Vasopressor===
|brandNames=
Phenylephrine is commonly used as a [[vasopressor]] to increase the blood pressure in unstable patients with [[hypotension]], especially resulting from septic shock. Such use is common in anesthesia or critical-care practices; it is especially useful in counteracting the hypotensive effect of [[epidural]] and [[subarachnoid]] [[anesthetics]], as well as the vasodilating effect of bacterial toxins and the inflammatory response in [[sepsis]] and [[systemic inflammatory response syndrome]]. It has the advantage of not being [[inotrope|inotropic]] or [[chronotropic]], so it strictly elevates the blood pressure without increasing the heart rate or contractility (reflex [[bradycardia]] may result from the blood pressure increase, however). This is especially useful if the heart is already tachycardic and/or has a [[cardiomyopathy]]. The elimination half life of phenylephrine is about 2.5 to 3.0 hours.
Because of its vasoconstrictive effect, phenylephrine (Neo-Synephrine) can cause severe necrosis if it infiltrates the surrounding tissues. Because of this, it should be given through a central line if at all possible. Damage may be prevented or mitigated by infiltrating the tissue with the alpha blocker phentolamine by subcutaneous injection.<ref>Cooper, B. E. (2008). Review and Update on Inotropes and Vasopressors. AACN Advanced Critical Care, 19, 5–15.</ref>
* ®<ref>{{Cite web | title = | url = }}</ref>
Phenylephrine hydrochloride at 0.25% is used as a vasoconstrictor in some [[suppository]] formulations.
<!--Look-Alike Drug Names-->
===Detumescent===
|lookAlike=
Phenylephrine is used by urologists to abort [[priapism]]. It is diluted significantly and injected directly into the [[Corpus cavernosum penis|corpora cavernosa]]. The mechanism of action is to cause constriction of the blood vessels entering into the penis, thus breaking the pathophysiologic cycle that continues the priapism.
==Side effects==
* A® — B®<ref name="www.ismp.org">{{Cite web | last = | first = | title = http://www.ismp.org | url = http://www.ismp.org | publisher = | date = }}</ref>
The primary side effect of phenylephrine is [[hypertension]]. Patients with hypertension are typically advised to avoid products containing it. [[Prostatic hyperplasia]] can also be symptomatically worsened by use, and chronic use can lead to rebound [[hyperemia]].<ref name=pharmnemonics>{{Cite book|author=Shen, Howard|title=Illustrated Pharmacology Memory Cards: PharMnemonics|year=2008|publisher=Minireview|isbn=1-59541-101-1|page=3}}</ref> Patients with a history of anxiety or panic disorders, or on anticonvulsant medication for epilepsy should not take this substance. The drug interaction might produce seizures. Some patients have been shown to have an upset stomach, severe abdominal cramping, and vomiting issues connected to taking this drug.
Because this medication is a [[sympathomimetic]] amine, it can also increase contractility force and increase output to the cardiac muscle. In other words, phenylephrine mimics norepinephrine binding to α-adrenoreceptors and can cause increased heart rate.
<!--Drug Shortage Status-->
Extended use may cause [[rhinitis medicamentosa]], a condition of [[Rebound effect|rebound]] [[nasal congestion]].
|drugShortage=
}}
==Substitute for pseudoephedrine==
<!--Pill Image-->
Pseudoephedrine and phenylephrine are both used as decongestants; and, until recently, [[pseudoephedrine]] was much more commonly available in the United States. This has changed because provisions of the [[Combat Methamphetamine Epidemic Act of 2005]] placed restrictions on the sale of pseudoephedrine products to prevent the [[clandestine chemistry|clandestine manufacture]] of [[methamphetamine]]. Since 2004, phenylephrine has been increasingly marketed as a substitute for pseudoephedrine; some manufacturers have changed the active ingredients of products to avoid the restrictions on sales.<ref name="HeraldTribune"/> Phenylephrine has been off [[patent]] for some time, and many generic brands are available.
==Questions about effectiveness==
{{PillImage
Pharmacists Leslie Hendeles and Randy Hatton of the [[University of Florida]] suggested in 2006 that oral phenylephrine is ineffective as a decongestant at the 10-mg dose used, arguing that the studies used for the regulatory approval of the drug in the United States in 1976 were inadequate to prove effectiveness at the 10-mg dose, and safety at higher doses.<ref name="Hendeles2006">{{cite journal|author=Heldeles, L. and Hatton, R.|title=Oral phenylephrine: An ineffective replacement for pseudoephedrine?|journal=Journal of Allergy and Clinical Immunology|volume=118|issue=1|pages=279–280|pmid=16815167|year=2006|doi=10.1016/j.jaci.2006.03.002}}</ref> Other pharmacists have expressed concerns over phenylephrine's effectiveness as a nasal decongestant,<ref name="UFL1">{{cite web
|fileName=No image.jpg|This image is provided by the National Library of Medicine.
|url=http://news.ufl.edu/2006/07/19/decongensant/
|drugName=
|author=University of Florida
|NDC=
|title=UF researchers question effectiveness of decongestant
|drugAuthor=
|date=2006-07-19
|ingredients=
|accessdate=2008-03-15}}</ref> and other clinicians have indicated concern for regulatory actions that reduced the availability of pseudoephedrine.<ref name="pmid16484253">{{cite web|author=Eccles R|title=Phenylephrine an ineffective replacement for pseudoephedrine in response to the methamphetamine problem in the USA|url=http://www.bmj.com/cgi/eletters/332/7538/382-b|date=May 2006|publisher=BMJ}}<br />'''Rapid Response to'''<br />{{cite journal|author=Tanne JH|title=Methamphetamine epidemic hits middle America|journal=BMJ|volume=332|issue=7538|pages=382|date=February 2006|pmid=16484253|doi=10.1136/bmj.332.7538.382-b|url=|pmc=1370997}}</ref><ref name="BJM">{{cite journal|author=Eccles, R.|doi=10.1111/j.1365-2125.2006.02833.x|title=Substitution of phenylephrine for pseudoephedrine as a nasal decongeststant. An illogical way to control methamphetamine abuse|journal=British Journal of Clinical Pharmacology|volume=63|pages=10–14|pmid=17116124|year=2007|issue=1|pmc=2000711}} (January 2007)</ref> A subsequent meta-analysis by the same researchers concluded that the evidence for its effectiveness is insufficient,<ref name="Annals">{{cite journal|author=Hatton, R.C. et al.|url=http://www.theannals.com/cgi/content/abstract/aph.1H679v1|title=Efficacy and Safety of Oral Phenylephrine: A Systematic Review and Meta-Analysis|journal=Annals of Pharmacotherapy|volume=41|pages=381–390|doi=10.1345/aph.1H679|pmid=17264159|year=2007|format=abstract|issue=3}}(published online Jan 2007)</ref> though another meta-analysis published shortly thereafter by researchers from [[GlaxoSmithKline]] found the standard 10-mg dose to be significantly more effective than a placebo.<ref name="GSK">{{cite pmid|17692721}}{{medrs|date=August 2012}}</ref> Additionally, two studies published in 2009 examined the effects of phenylephrine on symptoms of [[allergic rhinitis]] by exposing sufferers to pollen in a controlled, indoor environment. Neither study was able to distinguish between the effects of phenylephrine or a placebo.<ref name="danzig09">{{Cite pmid|19230461}}</ref><ref name="yao09">{{Cite pmid|19441605}}</ref> Pseudoephedrine<ref name="danzig09" /> and [[loratadine]]-[[montelukast]] therapy<ref name="yao09" /> were found to be significantly more effective than both phenylephrine and placebo.
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The [[Food and Drug Administration]] has stood by its 1976 approval of phenylephrine for nasal congestion as the debate continues.<ref name="HeraldTribune">{{cite news|author=Hilenmeyer, K.|url=http://www.heraldtribune.com/apps/pbcs.dll/article?AID=/FP/20070130/HEALTHMATTERS/70129001/1025/NEWS06|title=All stuffed up|publisher=Southwest Florida Herald-Tribune|date=30 January 2007}}</ref>
<!--Label Display Image-->
==References==
{{LabelImage
{{reflist|2}}
|fileName={{PAGENAME}}11.png|This image is provided by the National Library of Medicine.
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Black Box Warning
Title
See full prescribing information for complete Boxed Warning.
ConditionName:
Content
Overview
Phenylephrine (injection) is a that is FDA approved for the {{{indicationType}}} of . There is a Black Box Warning for this drug as shown here. Common adverse reactions include .
Adult Indications and Dosage
FDA-Labeled Indications and Dosage (Adult)
Mild or Moderate Hypotension
SUBCUTANEOUSLY OR INTRAMUSCULARLY: Usual dose, from 2 mg to 5 mg. Range, from 1 mg to 10 mg. Initial dose should not exceed 5 mg.
INTRAVENOUSLY: Usual dose, 0.2 mg. Range, from 0.1 mg to 0.5 mg. Initial dose should not exceed 0.5 mg.
Injections should not be repeated more often than every 10 to 15 minutes. A 5 mg intramuscular dose should raise blood pressure for one to two hours. A 0.5 mg intravenous dose should elevate the blood pressure for about 15 minutes.
Severe Hypotension and Shock - Including Drug-Related Hypotension
Blood volume depletion should always be corrected as fully as possible before any vasopressor is administered. When, as an emergency measure, intraaortic pressures must be maintained to prevent cerebral or coronary artery ischemia, phenylephrine can be administered before and concurrently with blood volume replacement.
Hypotension and occasionally severe shock may result from overdosage or idiosyncrasy following the administration of certain drugs, especially adrenergic and ganglionic blocking agents, rauwolfia and veratrum alkaloids and phenothiazine tranquilizers. Patients who receive a phenothiazine derivative as preoperative medication are especially susceptible to these reactions. As an adjunct in the management of such episodes, Phenylephrine Hydrochloride Injection is a suitable agent for restoring blood pressure.
Higher initial and maintenance doses of phenylephrine are required in patients with persistent or untreated severe hypotension or shock. Hypotension produced by powerful peripheral adrenergic blocking agents, chlorpromazine or pheochromocytomectomy may also require more intensive therapy.
Continuous Infusion:
Add 10 mg of the drug (1 mL of 1 percent solution) to 500 mL of Dextrose Injection, USP or Sodium Chloride Injection, USP (providing a 1:50,000 solution). To raise the blood pressure rapidly, start the infusion at about 100 mcg to 180 mcg per minute (based on 20 drops per mL this would be 100 to 180 drops per minute). When the blood pressure is stabilized (at a low normal level for the individual), a maintenance rate of 40 mcg to 60 mcg per minute usually suffices (based on 20 drops per mL this would be 40 to 60 drops per minute). If the drop size of the infusion system varies from the 20 drops per mL the dose must be adjusted accordingly.
If a prompt initial pressor response is not obtained, additional increments of phenylephrine (10 mg or more) are added to the infusion bottle. The rate of flow is then adjusted until the desired blood pressure level is obtained. (In some cases, a more potent vasopressor, such as norepinephrine bitartrate, may be required.) Hypertension should be avoided. The blood pressure should be checked frequently. Headache and/or bradycardia may indicate hypertension. Arrhythmias are rare.
Spinal Anesthesia-Hypotension
Routine parenteral use of phenylephrine has been recommended for the prophylaxis and treatment of hypotension during spinal anesthesia. It is best administered subcutaneously or intramuscularly three or four minutes before injection of the spinal anesthetic. The total requirement for high anesthetic levels is usually 3 mg, and for lower levels, 2 mg. For hypotensive emergencies during spinal anesthesia, phenylephrine may be injected intravenously, using an initial dose of 0.2 mg. Any subsequent dose should not exceed the previous dose by more than 0.1 mg to 0.2 mg and no more than 0.5 mg should be administered in a single dose.
To combat hypotension during spinal anesthesia in children, a dose of 0.5 mg to 1 mg per 25 pounds body weight, administered subcutaneously or intramuscularly, is recommended.
Prolongation of Spinal Anesthesia
The addition of 2 mg to 5 mg of phenylephrine hydrochloride to the anesthetic solution increases the duration of motor block by as much as approximately 50 percent without any increase in the incidence of complications such as nausea, vomiting or blood pressure disturbances.
Vasoconstrictor for Regional Analgesia
Concentrations about ten times those employed when epinephrine is used as a vasoconstrictor are recommended. The optimum strength is 1:20,000 (made by adding 1 mg of phenylephrine hydrochloride to every 20 mL of local anesthetic solution). Some pressor responses can be expected when 2 mg or more are injected.
Paroxysmal Supraventricular Tachycardia
Rapid intravenous injection (within 20 to 30 seconds) is recommended. The initial dose should not exceed 0.5 mg, and subsequent doses, which are determined by the initial blood pressure response, should not exceed the preceding dose by more than 0.1 mg to 0.2 mg and should never exceed 1 mg.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
Vasoconstriction and Pupil Dilation
Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% is especially useful when rapid and powerful dilation of the pupil without cycloplegia and reduction of congestion in the capillary bed are desired. A drop of a suitable topical anesthetic may be applied, followed in a few minutes by 1 drop of Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% on the upper limbus. The anesthetic prevents stinging and consequent dilution of the solution by lacrimination. It may occasionally be necessary to repeat the instillation after one hour, again preceded by the use of the topical anesthetic.
Uveitis
Posterior Synechiae: Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% may be used in patients with uveitis when synechiae are present or may develop. The formation of synechiae may be prevented by the use of this solution and atropine or other cycloplegics to produce wide dilation of the pupil. For recently formed posterior synechiae one drop of Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% may be applied to the upper surface of the cornea and be repeated as necessary, not to exceed three times. Treatment may be continued the following day, if necessary. Atropine sulfate and the application of hot compresses should also be used if indicated.
Glaucoma
Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% may be used with miotics in patients with open angle glaucoma. It reduces the difficulties experienced by the patient because of the small field produced by miosis, and still it permits and often supports the effect of the miotic in lowering the intraocular pressure in open angle glaucoma. Hence, there may be marked improvement in visual acuity after using Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% in conjunction with miotic drugs.
Surgery
When a short-acting mydriatic is needed for wide dilation of the pupil before intraocular surgery, Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% may be applied topically from 30 to 60 minutes before the operation.
Refraction
Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% may be used effectively to increase mydriasis with homatropine hydrobromide, cyclopentolate hydrochloride, tropicamide hydrochloride and atropine sulfate.
One drop of the preferred cycloplegic is placed in each eye, followed in 5 minutes by one drop of Phenylephrine Hydrochloride Ophthalmic Solution, 2.5%. Since adequate cycloplegia is achieved at different time intervals after the instillation of the necessary number of drops, different cycloplegics will require different waiting periods to achieve adequate cycloplegia.
Off-Label Use and Dosage (Adult)
Guideline-Supported Use
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Developed by:
Class of Recommendation:
Strength of Evidence:
Dosing Information
Dosage
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There is limited information regarding Off-Label Guideline-Supported Use of Phenylephrine (injection) in adult patients.
Non–Guideline-Supported Use
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Dosing Information
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There is limited information regarding Off-Label Non–Guideline-Supported Use of Phenylephrine (injection) in adult patients.
Pediatric Indications and Dosage
FDA-Labeled Indications and Dosage (Pediatric)
Condition1
Dosing Information
Dosage
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There is limited information regarding FDA-Labeled Use of Phenylephrine (injection) in pediatric patients.
Off-Label Use and Dosage (Pediatric)
Guideline-Supported Use
Condition1
Developed by:
Class of Recommendation:
Strength of Evidence:
Dosing Information
Dosage
Condition2
There is limited information regarding Off-Label Guideline-Supported Use of Phenylephrine (injection) in pediatric patients.
Non–Guideline-Supported Use
Condition1
Dosing Information
Dosage
Condition2
There is limited information regarding Off-Label Non–Guideline-Supported Use of Phenylephrine (injection) in pediatric patients.
Contraindications
Phenylephrine Hydrochloride Injection should not be used in patients with severe hypertension, ventricular tachycardia or in patients who are hypersensitive to it or to any of the components.
Ophthalmic solutions of phenylephrine HCl are contraindicated in patients with anatomically narrow angles or narrow angle glaucoma. Phenylephrine HCl may be contraindicated in low birth weight infants and in some elderly adults with severe arteriosclerotic cardiovascular or cerebrovascular disease. Phenylephrine HCl may be contraindicated during intraocular operative procedures when the corneal epithelial barrier has been disturbed. This preparation is also contraindicated in persons with a known sensitivity to phenylephrine HCl or any of its components.
Warnings
Title
See full prescribing information for complete Boxed Warning.
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Content
If used in conjunction with oxytocic drugs, the pressor effect of sympathomimetic pressor amines is potentiated (see PRECAUTIONS, Drug Interactions). The obstetrician should be warned that some oxytocic drugs may cause severe persistent hypertension and that even a rupture of a cerebral blood vessel may occur during the postpartum period.
This product contains sodium metabisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people. The overall prevalence of sulfite sensitivity in the general population is unknown and probably low. Sulfite sensitivity is seen more frequently in asthmatic than in nonasthmatic people.
Precautions
Phenylephrine hydrochloride should be employed only with extreme caution in elderly patients or in patients with hyperthyroidism, bradycardia, partial heart block, myocardial disease or severe arteriosclerosis.
Adverse Reactions
Clinical Trials Experience
Headache, reflex bradycardia, excitability, restlessness and rarely arrhythmias.
Body as a Whole
Cardiovascular
Digestive
Endocrine
Hematologic and Lymphatic
Metabolic and Nutritional
Musculoskeletal
Neurologic
Respiratory
Skin and Hypersensitivy Reactions
Special Senses
Urogenital
Miscellaneous
Postmarketing Experience
There is limited information regarding Postmarketing Experience of Phenylephrine (injection) in the drug label.
Body as a Whole
Cardiovascular
Digestive
Endocrine
Hematologic and Lymphatic
Metabolic and Nutritional
Musculoskeletal
Neurologic
Respiratory
Skin and Hypersensitivy Reactions
Special Senses
Urogenital
Miscellaneous
Drug Interactions
MAO Inhibitors
The pressor effect of sympathomimetic pressor amines is markedly potentiated in patients receiving monoamine oxidase inhibitors (MAOI). Therefore, when initiating pressor therapy in these patients, the initial dose should be small and used with due caution. The pressor response of adrenergic agents may also be potentiated by tricyclic antidepressants.
Animal reproduction studies have not been conducted with phenylephrine. It is also not known whether phenylephrine can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Phenylephrine should be given to a pregnant woman only if clearly needed.
Australian Drug Evaluation Committee (ADEC) Pregnancy Category
There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Phenylephrine (injection) in women who are pregnant.
Labor and Delivery
If vasopressor drugs are either used to correct hypotension or added to the local anesthetic solution, the obstetrician should be cautioned that some oxytocic drugs may cause severe persistent hypertension and that even a rupture of a cerebral blood vessel may occur during the postpartum period.
Nursing Mothers
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when phenylephrine hydrochloride is administered to a nursing woman.
Pediatric Use
To combat hypotension during spinal anesthesia in children, a dose of 0.5 mg to 1 mg per 25 pounds of body weight, administered subcutaneously or intramuscularly, is recommended.
Geriatic Use
There is no FDA guidance on the use of Phenylephrine (injection) with respect to geriatric patients.
Gender
There is no FDA guidance on the use of Phenylephrine (injection) with respect to specific gender populations.
Race
There is no FDA guidance on the use of Phenylephrine (injection) with respect to specific racial populations.
Renal Impairment
There is no FDA guidance on the use of Phenylephrine (injection) in patients with renal impairment.
Hepatic Impairment
There is no FDA guidance on the use of Phenylephrine (injection) in patients with hepatic impairment.
Females of Reproductive Potential and Males
There is no FDA guidance on the use of Phenylephrine (injection) in women of reproductive potentials and males.
Immunocompromised Patients
There is no FDA guidance one the use of Phenylephrine (injection) in patients who are immunocompromised.
Administration and Monitoring
Administration
Oral
Intravenous
Intramuscular
Subcutaneous
Monitoring
There is limited information regarding Monitoring of Phenylephrine (injection) in the drug label.
IV Compatibility
There is limited information regarding IV Compatibility of Phenylephrine (injection) in the drug label.
Overdosage
Acute Overdose
Signs and Symptoms
Overdosage may induce ventricular extrasystole and short paroxysms of ventricular tachycardia, a sensation of fullness in the head and tingling of the extremities.
The oral LD50 in the rat is 350 mg/kg, in the mouse 120 mg/kg.
Management
Should an excessive elevation of blood pressure occur, it may be immediately relieved by an α-adrenergic blocking agent (e.g. phentolamine).
Chronic Overdose
There is limited information regarding Chronic Overdose of Phenylephrine (injection) in the drug label.
Pharmacology
There is limited information regarding Phenylephrine (injection) Pharmacology in the drug label.
Mechanism of Action
Phenylephrine hydrochloride produces vasoconstriction that lasts longer than that of epinephrine and ephedrine. Responses are more sustained than those to epinephrine, lasting 20 minutes after intravenous and as long as 50 minutes after subcutaneous injection. Its action on the heart contrasts sharply with that of epinephrine and ephedrine, in that it slows the heart rate and increases the stroke output, producing no disturbance in the rhythm of the pulse.
Phenylephrine is a powerful postsynaptic alpha-receptor stimulant with little effect on the beta receptors of the heart. In therapeutic doses, it produces little if any stimulation of either the spinal cord or cerebrum. A singular advantage of this drug is the fact that repeated injections produce comparable effects.
Structure
Phenylephrine hydrochloride is a vasoconstrictor and pressor drug chemically related to epinephrine and ephedrine. Phenylephrine hydrochloride is a synthetic sympathomimetic agent in sterile form for parenteral injection. Chemically, phenylephrine hydrochloride is (-)-m-Hydroxy-α-[(methylamino)methyl]benzyl alcohol hydrochloride, and has the following structural formula:
Each mL contains: Phenylephrine Hydrochloride 10 mg; Sodium Chloride 3.5 mg; Sodium Citrate Dihydrate 4 mg; Citric Acid Monohydrate 1 mg; Sodium Metabisulfite 2 mg; Water for Injection q.s. pH adjusted with Sodium Hydroxide and/or Hydrochloric Acid if necessary. pH 3.0-6.5.
Pharmacodynamics
The predominant actions of phenylephrine are on the cardiovascular system. Parenteral administration causes a rise in systolic and diastolic pressures in man and other species. Accompanying the pressor response to phenylephrine is a marked reflex bradycardia that can be blocked by atropine; after atropine, large doses of the drug increase the heart rate only slightly. In man, cardiac output is slightly decreased and peripheral resistance is considerably increased. Circulation time is slightly prolonged, and venous pressure is slightly increased; venous constriction is not marked. Most vascular beds are constricted; renal splanchnic, cutaneous and limb blood flows are reduced but coronary blood flow is increased. Pulmonary vessels are constricted, and pulmonary arterial pressure is raised.
The drug is a powerful vasoconstrictor with properties very similar to those of norepinephrine but almost completely lacking the chronotropic and inotropic actions on the heart. Cardiac irregularities are seen only very rarely even with large doses.
Pharmacokinetics
There is limited information regarding Pharmacokinetics of Phenylephrine (injection) in the drug label.
Nonclinical Toxicology
No long-term animal studies have been done to evaluate the potential of phenylephrine in these areas.
Clinical Studies
There is limited information regarding Clinical Studies of Phenylephrine (injection) in the drug label.
How Supplied
Phenylephrine Hydrochloride Injection, USP 1% (10 mg/mL) is supplied as follows:
NDC 0641-6088-25
1 mL Single Dose vial packaged in 25s
Store at 20°-25°C (68°-77°F), excursions permitted to 15°-30°C (59°-86°F). PROTECT FROM LIGHT. Keep covered in carton until time of use. FOR SINGLE USE ONLY. DISCARD UNUSED PORTION.
Phenylephrine Hydrochloride Ophthalmic Solution, 2.5% in plastic DROP-TAINER* dispensers:
3mL NDC 61314-342-01
5mL NDC 61314-342-02
Storage
There is limited information regarding Phenylephrine (injection) Storage in the drug label.
Images
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