View source for WBR0092

{{WBRQuestion
|QuestionAuthor=Gonzalo Romero (reviewed by [[user: Jad Al Danaf|Jad Al Danaf]], {{Rim}})
|ExamType=USMLE Step 1
|MainCategory=Pharmacology
|SubCategory=Genitourinary
|MainCategory=Pharmacology
|SubCategory=Genitourinary
|MainCategory=Pharmacology
|SubCategory=Genitourinary
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Genitourinary
|MainCategory=Pharmacology
|SubCategory=Genitourinary
|MainCategory=Pharmacology
|SubCategory=Genitourinary
|MainCategory=Pharmacology
|SubCategory=Genitourinary
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Genitourinary
|Prompt=A 35 year-old male presents to the emergency room for persistent and painful erection of 5 hours 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 the use of a medication to help him sleep for the last 6 weeks.  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?
|Explanation=[[Trazadone]] is an atypical antidepressant used mainly to treat insomnia.  With high doses it can be used to treat depression.  An important but rare side effect is [[priapism]], which is a painful sustained penile erection of more than 4 hours.  It also causes [[sedation]], [[nausea]], and postural [[hypotension]].  It acts by inhibiting serotonin reuptake and belongs to the serotonin antagonist and reuptake inhibitor (SARI) class.
|AnswerA=Inhibits serotonin reuptake
|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.
|AnswerB=Inhibits norepinephrine reuptake
|AnswerBExp=[[Maprotiline]] is an atypical antidepressant which blocks [[norepinephrine]] reuptake.  It can cause [[sedation]] as a side effect.
|AnswerC=Serotonin receptor agonist
|AnswerCExp=[[Buspirone]], which is used to treat general anxiety disorder, stimulates [[serotonin]] (5-HT1a) receptors.  It does not cause [[sedation]], [[addiction]] or [[tolerance]].
|AnswerD=Alpha-2 receptor antagonist
|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.
[[Trazodone]] is thought to cause [[priapism]] through its antagonistic effect on alpha adrenergic receptors.
|AnswerE=Modulating GABA receptors
|AnswerEExp=Different drugs act by increasing the opening of [[GABA]] channels such as [[benzodiazepines]] and [[barbiturates]].
|EducationalObjectives=Trazadone is an atypical antidepressant used to treat [[insomnia]] in patients with [[depression]].  Its inhibits [[serotonin]] reuptake and can cause priapism, on rare occasions, 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.
|RightAnswer=A
|WBRKeyword=trazodone, priapism, depression, insomnia, serotonin reuptake inhibitor
|Approved=Yes
}}
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