Rizatriptan: pharmacological differences from sumatriptan and clinical results

Rizatriptan and sumatriptan are selective 5-HT(1B/1D) receptor agonists for theacute treatment of migraine. For oral formulations, the time to maximum plasma concentration is reached earlier with rizatriptan than with sumatriptan (1 h versus 2-2.5 h) and rizatriptan has greater bioavailability than sumatriptan (45% versus 15%). These pharmacological advantages appear to translate into a faster onset of action and a better overall response for oral rizatriptan versus oral sumatriptan. The two drugs have been directly compared in randomized, double-blind, placebo-controlled clinical trials of patients with moderate or severe migraine attacks. Rizatriptan 10 mg was generally superior to sumatriptan on a measure of time-to-pain-relief within 2 h, where pain relief was defined as a reduction of pain to mild or none (odds ratio for rizatriptan versus sumatriptan 100 mg = 1.21; odds ratios for rizatriptan 10 mg versus sumatriptan 50 mg = 1.14 and 1.10 in two studies). Rizatriptan 10 mg was also superior to sumatriptan on the International Headache Society recommended endpoint of the percentage of patients pain free at 2 h (40% for rizatriptan 10 mg, 33% for sumatriptan 100 mg, and 35% for sumatriptan 50 mg). Further advantages for rizatriptan were seen on stringent outcome measures of the percentage of patients who were completely free of all symptoms at 2 h, patient satisfaction with medication at 2 h, and 24-h sustained pain-free response. 5-HT(1B/1D) receptor agonists are contraindicated in patients with coronary artery disease because of their potential to cause vasoconstriction. In clinical trials which excluded such patients, rizatriptan and sumatriptan were both well-tolerated. The most common side-effects on both drugs occurred in <10% of patients and consisted of dizziness, drowsiness, and asthenia/fatigue. The adverse events were usually mild or moderate in severity and short-lasting.