Sumatriptan. A reappraisal of its pharmacology and therapeutic efficacy in the acute treatment of migraine and cluster headache.

Sumatriptan is a potent and selective agonist at a vascular serotonin1 (5-hydroxytryptamine1; 5-HT1) receptor subtype (similar to 5-HT1D) and is used in acute treatment of migraine and cluster headache. Following administration of sumatriptan 100mg orally, relief of migraine headache (at 2 hours) was achieved in 50 to 67% of patients compared with 10 to 31% with placebo in controlled clinical trials. In a comparative study, oral administration of sumatriptan 100mg consistently achieved significantly greater response rates than a fixed combination of ergotamine 2mg plus caffeine 200mg during 3 consecutive migraine attacks (66 vs 48% for first attack). Oral sumatriptan 100mg was also more effective than aspirin 900mg plus metoclopramide 10mg orally in a similar study. In the majority of controlled clinical trials, headache relief (at 1 hour after administration) was achieved in 70 to 80% of patients with migraine receiving sumatriptan 6mg subcutaneously compared with 18 to 26% of placebo recipients. Approximately 40% of patients who initially responded to oral or subcutaneous sumatriptan experienced recurrence of their headache, usually within 24 hours, but the majority of these patients responded well to a further dose of sumatriptan. Patients with cluster headache were treated for acute attacks with sumatriptan 6mg subcutaneously or placebo in 2 crossover trials. Headache relief was achieved within 15 minutes in 74 and 75% of patients receiving sumatriptan in these studies compared with 26 and 35%, respectively, with placebo. Patients receiving sumatriptan 12mg had a similar response rate as those receiving 6mg, but the higher dose was associated with an increased incidence of adverse events. Based on extensive safety data pooled from controlled clinical trials, sumatriptan is generally well tolerated and most adverse events are transient. The most frequently reported adverse events following oral administration include nausea, vomiting, malaise, fatigue and dizziness. Injection site reactions (minor pain and redness of brief duration) occur in approximately 40% of patients receiving subcutaneous sumatriptan, although the incidence appears to be markedly reduced when patients self-administer the drug with an auto-injector. Chest symptoms (mainly tightness and pressure) occur in 3 to 5% of sumatriptan recipients, but have not been associated with myocardial ischaemia except in a few isolated cases. Sumatriptan is contraindicated in patients with ischaemic heart disease, angina pectoris including Prinzmetal (variant) angina, previous myocardial infarction and uncontrolled hypertension, but is not contraindicated in patients with migraine and asthma. Data from long term studies in acute treatment of migraine and cluster headache suggest that sumatriptan remains effective and well tolerated over several months.(ABSTRACT TRUNCATED AT 400 WORDS)