WBR0092

Author	[[PageAuthor::Gonzalo Romero (reviewed by Jad Al Danaf, Rim Halaby, M.D. [1])]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Genitourinary
Prompt	[[Prompt::A 35 year-old male presents to the emergency room for persistent and painful erection of 5 hour duration. The patient usually has erections throughout the night and in the morning but they only last for a couple of minutes. He denies any sexual encounter the previous night or any erectile dysfunction for which he takes medications. The patient has a history of depression for which he is on medical therapy. He also reports that his psychiatrist recently prescribed him a medication to help him sleep. His vitals are the following: blood pressure of 126/70 mmHg, regular heart rate of 87 beats/minute, respiratory rate of 16 per minute, and temperature of 37 °C. The emergency medicine doctor is concerned that the sleep medication is associated with his prolonged painful erection. Which of the following is the mechanism of action of the sleep medication that is most likely prescribed to this patient?]]
Answer A	AnswerA::Inhibits serotonin reuptake
Answer A Explanation	[[AnswerAExp::The sleep medication prescribed for the patient is most likely trazodone. It is an atypical antidepressant that belongs to the serotonin antagonist and reuptake inhibitor (SARI) class of antidepressants. It is usually prescribed to treat insomnia in patients with major depressive symptoms, and has also been shown to have anxiolytic properties. Trazodone is thought to cause priapism through its antagonistic effect on alpha adrenergic receptors.]]
Answer B	AnswerB::Norepinephrine reuptake inhibitor
Answer B Explanation	[[AnswerBExp::Maprotiline is an atypical antidepressant which blocks norepinephrine reuptake. It can cause sedation as a side effect.]]
Answer C	AnswerC::Serotonin receptor agonist
Answer C Explanation	[[AnswerCExp::Buspirone, which is used to treat general anxiety disorder, stimulates serotonin (5-HT1a) receptors. It does not cause sedation, addiction or tolerance.]]
Answer D	AnswerD::Alpha-2 receptor antagonist
Answer D Explanation	[[AnswerDExp::Mirtazapine is an atypical antidepressant. It blocks alpha-2 receptors in the presynaptic neurons which increases the release of norepinephrine and serotonin. It causes sedation and therefore can be used in depressed patients with insomnia. It might also cause an increase in appetite with possible weight gain.]]
Answer E	AnswerE::GABA receptor agonist
Answer E Explanation	[[AnswerEExp::Different drugs act by increasing the opening of GABA channels such as benzodiazepines and barbiturates.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::Trazadone is an atypical antidepressant that belongs to the serotonin antagonist and reuptake inhibitor (SARI) class of antidepressants. Trazadone inhibits serotonin reuptake and is mainly used to treat insomnia. It can, at high doses, be used to treat depression. An important but rare side effect of trazadone is priapism, which is a painful sustained penile erection for more than 4 hours. Trazadone also causes sedation, nausea, and postural hypotension. Educational Objective: Trazadone is an atypical antidepressant used to treat insomnia in patients with depression. Its inhibits serotonin reuptake and can, on rare occasions, cause priapism due to its possible antagonistic effect on alpha adrenergic receptors. References: First Aid 2013, page 476; Abber RE et al. (1987). Priapism induced by chlorpromazine and trazodone: mechanism of action. J. Urol 137 (5): 1039–1042.]]
Approved	Approved::Yes
Keyword	WBRKeyword::trazodone, WBRKeyword::priapism, WBRKeyword::depression, WBRKeyword::insomnia, WBRKeyword::serotonin reuptake inhibitor
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::

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