WBR0942

Author	PageAuthor::William J Gibson
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Neurology
Prompt	[[Prompt::A 33-year-old woman presents to urgent care for a very painful headache. She recalls that prior to the onset of the headache, she experienced a bilateral loss of peripheral visual fields. She describes the pain as throbbing and localized to the frontotemporal areas. What is the mechanism of action of the most appropriate pharmacotherapy?]]
Answer A	AnswerA::5-HT 1B/1D agonist
Answer A Explanation	AnswerAExp::'''Correct:''' Sumatriptan is a serotonin analogue that acts as a 5-HT 1B/1D agonist to relieve migraine headaches.
Answer B	AnswerB::5-HT 3 antagonist
Answer B Explanation	AnswerBExp::'''Incorrect:''' This describes Ondansetron, an anti-emetic used in conjunction with chemotherapy. Ondansetron is not effective in treating migraine headaches.
Answer C	AnswerC::Cyclooxygenase inhibitor
Answer C Explanation	AnswerCExp::'''Incorrect:''' This is the mechanism of action of NSAIDs. While NSAIDs may be used to treat headaches, an acute migraine is more appropriately treated with sumatriptan.
Answer D	AnswerD::Potentiate GABA by increasing the frequency of Cl channel opening
Answer D Explanation	AnswerDExp::'''Incorrect:''' This describes the mechanism of action of benzodiazepines, which are not effective for the treatment of migraine headaches.
Answer E	AnswerE::Phosphodiesterase inhibitor
Answer E Explanation	AnswerEExp::'''Incorrect:''' This describes the mechanism of action of sildenafil. One side effect of sildenafil is headache.
Right Answer	RightAnswer::A
Explanation	[[Explanation::The patient in this vignette has a migraine headache. Migraines are often preceded by an “aura” and are characterized by severe pain localized mostly to the frontotemporal areas. Migraines are thought to be caused by irritation of CN V and release of substance P. Sumatriptan is an effective therapy for migraine headaches. Sumatriptan is structurally similar to serotonin (5HT), and is a 5-HT (types 5-HT1D and 5-HT1B) agonist. The specific receptor subtypes it activates are present on the cranial arteries and veins. Acting as an agonist at these receptors, sumatriptan reduces the vascular inflammation associated with migraines. Educational objective: Sumatriptan is a serotonin analogue that acts as a 5-HT 1B/1D agonist to relieve migraine headaches. References: First Aid 2013 page 274 First Aid 2013 page 467 Educational Objective: References: ]]
Approved	Approved::Yes
Keyword	WBRKeyword::Headache, WBRKeyword::Migraine, WBRKeyword::Migraine headache, WBRKeyword::Serotonin, WBRKeyword::5-HT, WBRKeyword::Mechanism
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::