Pharm 2 Final: Headache Drugs

Valproic Acid

MOA: Multiple mechanisms; increases GABA synthesis and decreases GABA degradation. Use: Migraine prophylaxis. SE: Monitor serum levels due to extensive drug interactions.

Amitriptyline

MOA: TCA; blocks reuptake of serotonin and NE. Use: Migraine prophylaxis. SE: Must take 3–4 weeks before becoming effective for headache prevention.

Aspirin

MOA: Non-selective COX inhibitor; irreversibly acetylates platelet COX. Use: Acute migraine treatment. SE: Antiplatelet effect lasts 14 days.

Naproxen

MOA: Non-selective COX inhibitor; blocks thromboxane synthesis and platelet aggregation, reducing serotonin release. Use: Acute migraine treatment. SE: Caution for GI side effects.

Propranolol

MOA: Non-selective beta-blocker; attenuates second phase of migraines by blocking beta-2-mediated vasodilation. Use: Migraine prophylaxis. SE: More CNS side effects than other beta-blockers.

Verapamil

MOA: Calcium channel blocker; may prevent vasoconstrictive phase of migraine. Use: Migraine prophylaxis. SE: Not first-line for migraine prophylaxis.

Gabapentin

MOA: Enhances GABA action. Use: Seizure disorders, post-herpetic neuralgia, migraine prophylaxis. SE: Sedation.

Botulinum Toxin A (Botox)

MOA: Disrupts ACh neurotransmission by preventing vesicle fusion with presynaptic membrane. Use: Migraine prophylaxis. SE: Delivered by injection; lasts weeks to months.

Ergotamine

MOA: Activates serotonin 5-HT1D/1B receptors; produces vasoconstriction. Some formulations contain caffeine for additional vasoconstrictive effect. Use: Acute migraine treatment. SE: Caffeine component can contribute to vasoconstriction.

Sumatriptan (Imitrex)

MOA: Activates serotonin 5-HT1D/1B receptors; produces vasoconstriction. Use: Acute migraine treatment. SE: Given subcutaneously; ~1 hour to relief; can cause coronary vasospasm (avoid in angina/CAD); risk of serotonin syndrome with SSRIs.