Most common drug used for prophylaxis of migraine is
**Core Concept**
Topiramate, a calcium channel blocker, and certain anticonvulsants are used for migraine prophylaxis, but the most common drug used for this purpose is a medication that acts on the serotonin system, specifically by inhibiting the reuptake of serotonin.
**Why the Correct Answer is Right**
The most effective medication for migraine prophylaxis is a serotonin reuptake inhibitor, specifically **Flunarizine** (Option C), which is a calcium channel blocker with a strong affinity for serotonin receptors. Flunarizine prevents the reuptake of serotonin, thereby increasing its availability in the synaptic cleft and reducing migraine frequency. This mechanism is more effective than other options like topiramate or certain anticonvulsants.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is a type of triptan used for acute migraine treatment, not prophylaxis.
**Option B:** Metoprolol is a beta-blocker used for hypertension and other cardiovascular conditions, not migraine prophylaxis.
**Option D:** Amitriptyline is a tricyclic antidepressant that can be used for migraine prophylaxis but is not the most common drug used for this purpose.
**Clinical Pearl / High-Yield Fact**
Migraine prophylaxis is often achieved by targeting the serotonin system, either by inhibiting its reuptake (as seen with flunarizine) or by preventing its breakdown (as seen with certain monoamine oxidase inhibitors).
**Correct Answer: C. Flunarizine**