WBR0093

Author	PageAuthor::Gonzalo Romero
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Behavioral Science/Psychiatry, MainCategory::Pharmacology
Sub Category	SubCategory::Neurology
Prompt	[[Prompt::A 75 year-old diabetic woman comes to the family department for a follow up. She has been non compliant with her medication. She has a 7-month history of non-radiating burning pain on her feet, which is increasing in intensity. Her vitals are BP=125/80 mm-Hg, HR=70, T=37C, RR=16. Her primary care physician orders HbA1c levels which are 15 mg/dL. The physician also orders other lab tests. While waiting for the other results the physician counsels the patient on medication adherence, diet and exercise. The physician is considering using duloxetine to control the patient’s feet pain. Which of the following is the mechanism of action of this drug?]]
Answer A	AnswerA::Inhibits specifically serotonin reuptake
Answer A Explanation	[[AnswerAExp::Incorrect. SSRIs specifically inhibit 5-HT reuptake. Examples are paroxetine, sertraline, citalopram and sertraline. They are used for depression, general anxiety disorder, bulimia bulimia, social phobias, OCD and PTSD. Their side effects are sexual dysfunction, GI distress. In excess they can cause serotonin syndrome if used in combination with drugs that increase Serotonin (confusion, hyperthermia, myoclonus, flushing, diarrhea and cardiovascular collapse).]]
Answer B	AnswerB::Inhibits serotonin and NE reuptake
Answer B Explanation	[[AnswerBExp::Correct. Venlaxafine has the same mechanism of action and is used for general anxiety disorder and panic disorders.]]
Answer C	AnswerC::Inhibits serotonin, NE and Dopamine metabolism
Answer C Explanation	[[AnswerCExp::Incorrect. MAO (monoamine oxidase) inhibitors increase the levels of NE, 5-HT and DA. They include drugs like: phenelzine, isocarboxacid, selegiline (selective MAO-B inhibitor). They are used mainly for atypical depression. Its major side effects are hypertensive crisis when combined with tyramine, a compound found in cheese and wine.]]
Answer D	AnswerD::Alpha-2 receptor antagonist
Answer D Explanation	[[AnswerDExp::Incorrect. Mirtazapine is an alpha-2 receptor antagonist. It is an atypical antidepressant which causes appetite increase and weight gain, therefore useful in the elderly and anorexic patients.]]
Answer E	AnswerE::Alpha-2 receptor agonist
Answer E Explanation	[[AnswerEExp::Incorrect. Methyldopa and clonidine are selective for α2-adrenergic agonists. Methyldopa is used to treat hypertension, especially in pregnant women. Clonidine can be used for hypertension, anxiety/panic disorder, and certain pain conditions.]]
Right Answer	RightAnswer::B
Explanation	[[Explanation::This patient is presenting with periphery diabetic neuropathy, therefore is prescribed duloxetine, which is a serotonin–norepinephrine reuptake inhibitor (SNRI). It inhibits NE and 5-HT reuptake. It has greater effect on NE. Its side effects are hypertension, sedation, nausea and stimulant effects. Educational Objective: Duloxetine is an atypical antidepressant, which can be used for peripheral diabetic neuropathy. It inhibits both NE and 5-HT reuptake, having a dual mechanism of action. Venlaxafine has the same mechanism of action as duloxetine. Wiki-Mnemonics: Duloxetine and velafaxine are DOBLE HITTERS = inhibit both NE and serotonin reuptake DUALxetine = dual mechanism of action (inhibit both NE and serotonin reuptake) References: First Aid 2013 page 472-476 Educational Objective: References: ]]
Approved	Approved::Yes
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