A teenager has seen her local physician complaining of persistent and severe headaches. Her physician diagnosed migraine and prescribes sumatriptan, which acts by which of the following mechanisms?
## **Core Concept**
The question tests understanding of the pharmacological management of migraines, specifically the mechanism of action of sumatriptan. Migraines are a type of headache disorder characterized by recurrent episodes of severe headaches, often accompanied by sensitivity to light and sound. Sumatriptan is a medication used to treat acute migraine attacks.
## **Why the Correct Answer is Right**
Sumatriptan acts by selectively agonizing **serotonin (5-HT) receptors**, specifically the 5-HT1B and 5-HT1D subtypes. This agonism leads to **vasoconstriction** of intracranial blood vessels and **inhibition of pro-inflammatory neuropeptide release**, which are thought to contribute to the pathophysiology of migraines. By causing vasoconstriction, sumatriptan reduces the blood flow to the affected areas of the brain, which in turn alleviates the headache.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because sumatriptan does not primarily work by blocking beta-adrenergic receptors; that mechanism is more relevant to beta-blockers used in migraine prophylaxis.
- **Option B:** This option is incorrect as sumatriptan's action is not mainly through antagonism of dopamine receptors; drugs that act on dopamine receptors are used in other conditions, such as schizophrenia or as antiemetics.
- **Option C:** This option is incorrect because sumatriptan does not work primarily by inhibiting the synthesis of prostaglandins; that mechanism is relevant to nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that sumatriptan is effective for the acute treatment of migraine attacks but is not used for migraine prophylaxis. It should be used early in the treatment of a migraine attack for optimal effectiveness. A classic clinical correlation is that sumatriptan can cause **chest tightness** as a side effect, likely due to coronary vasoconstriction.
## **Correct Answer:** D. Selective agonism of serotonin 5-HT1B and 5-HT1D receptors.