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 complains of worsening pain in her feet. The pain started almost 7 months ago and has been increasing in severity lately. The pain is localized in both feet, non-radiating and burning in nature. The patient admits that she has not been compliant with her diabetes medication. Her vitals are blood pressure of 125/80 mmHg, heart rate of 70 beats/minute, temperature of 37 C and respiratory rate of 16 per minute. On physical exam, the patient has decreased sensation in the right and left legs below the knees and decreased Achilles tendon reflexes bilaterally. Laboratory tests reveal an HbA1c level of 15 mg/dL. The patient is educated about the important of adherence to diabetes medication and lifestyle changes to slow the progression of the different complications of diabetes. The physician also considers the prescription of duloxetine to relieve the patient’s symptoms of pain in the feet. Which of the following is the mechanism of action of this drug?]]
Answer A	AnswerA::Serotonin reuptake inhibitor
Answer A Explanation	[[AnswerAExp::Selective serotonin reuptake inhibitors (SSRIs) inhibit 5-HT reuptake. Examples of SSRI are paroxetine, sertraline, citalopram and sertraline. They are used for depression, general anxiety disorder, bulimia nervosa, social phobia, OCD and PTSD. Their side effects include sexual dysfunction and gastrointestinal distress. SSRI can cause serotonin syndrome if used in combination with other drugs that increase serotonin.]]
Answer B	AnswerB::Serotonin and norepinephrine reuptake inhibitor
Answer B Explanation	[[AnswerBExp::Venlafaxine is a serotonin and norepinephrine reuptake inhibitor and is used for general anxiety disorder and panic disorders.]]
Answer C	AnswerC::Serotonin, norepinephrine and dopamine metabolism inhibitor
Answer C Explanation	[[AnswerCExp::Monoamine oxidase inhibitors (MOI) increase the levels of norepinephrine, 5-HT and dopamine. MOI include phenelzine, isocarboxazid and selegiline which is a selective MAO-B inhibitor. They are prescribed mainly for atypical depression. The major side effects of MOI 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::Mirtazapine is an alpha-2 receptor antagonist. It is an atypical antidepressant which causes increase in appetite and weight gain, thus useful in the elderly and anorexic patients.]]
Answer E	AnswerE::Alpha-2 receptor agonist
Answer E Explanation	[[AnswerEExp::Methyldopa and clonidine are selective 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 peripheral diabetic neuropathy for which she is prescribed duloxetine. Duloxetine is a serotonin norepinephrine reuptake inhibitor (SNRI). It inhibits norepinephrine and 5-HT reuptake. Its side effects are hypertension, sedation, nausea and stimulant effects. Wiki-Mnemonics: Duloxetine and velafaxine are DOUBLE HITTERS = They inhibit both NE and serotonin reuptake DUALxetine = dual mechanism of action (inhibit both norepinephrine and serotonin reuptake) Educational Objective: Duloxetine is an atypical antidepressant, which can be used for peripheral diabetic neuropathy. It inhibits both norepinephrine and 5-HT reuptake, having a dual mechanism of action. References: First Aid 2014 page page 519; First Aid 2013 page 472-476]]
Approved	Approved::Yes
Keyword	WBRKeyword::Diabetic neuropathy, WBRKeyword::duloxetine, WBRKeyword::endocrinology, WBRKeyword::Pharmacology, WBRKeyword::Diabetes mellitus, WBRKeyword::diabetes
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