**Question:** What is the drug of choice for an acute attack of migraine?

**Core Concept:** Migraine is a primary headache disorder characterized by recurrent, severe, and throbbing headaches. Treatment for acute migraine attacks aims to relieve symptoms and prevent future attacks.

**Why the Correct Answer is Right:**

Correct Answer: **D.** Sumatriptan (Imitrex)

Sumatriptan is a selective agonist of the 5-HT1B/1D receptors, located on the vascular smooth muscle cells of the meninges. Stimulation of these receptors causes constriction of the blood vessels and reduces the vascular dilation associated with migraine attacks. This leads to pain relief and improved migraine symptoms.

**Why Each Wrong Option is Incorrect:**

A. **Option A (Almotriptan):** Almotriptan is another 5-HT1B/1D receptor agonist, similar to sumatriptan. However, it is less potent and has a shorter duration of action, making it less effective than sumatriptan.

B. **Option B (Naratriptan):** Naratriptan is another selective 5-HT1B/1D receptor agonist with a shorter duration of action compared to sumatriptan. It is less potent and effective than sumatriptan.

C. **Option C (Rizatriptan):** Rizatriptan is another selective 5-HT1B/1D receptor agonist with a shorter duration of action than sumatriptan. It is also less potent and effective than sumatriptan.

**Clinical Pearl:**

In clinical practice, sumatriptan is preferred for the treatment of acute migraine attacks due to its higher potency, longer duration of action, and better efficacy compared to the other triptans (almotriptan, naratriptan, and rizatriptan).

**Explanation of the Options:**

A. Almotriptan: Less potent and has a shorter duration of action than sumatriptan.
B. Naratriptan: Less potent and has a shorter duration of action than sumatriptan.
C. Rizatriptan: Less potent and has a shorter duration of action than sumatriptan.

**Why Sumatriptan is Preferred:**

Sumatriptan is considered the gold standard of triptans due to its higher potency, longer duration of action, and better efficacy compared to the other triptans (almotriptan, naratriptan, and rizatriptan). This makes it a preferable choice for treating acute migraine attacks.

**Sumatriptan Mechanism:**

Sumatriptan acts as a selective serotonin 1B and 1D receptor agonist, which helps in constricting the meningeal blood vessels and reducing the pain associated with migraine attacks. The longer duration of action enables a single dose to provide prolonged relief from migraine symptoms, especially when compared to the other triptans.