The long-term tolerability and efficacy of oral zolmitriptan (Zomig, 311C90) in the acute treatment of migraine. An international study. The International 311C90 Long-term Study Group.

This international open-label study evaluated the tolerability and efficacy of zolmitriptan (Zomig, 311C90), a selective 5-HT1B/1D receptor agonist, in the long-term treatment of multiple migraine attacks. Patients who had previously participated in placebo-controlled zolmitriptan studies were recruited. A total of 2058 patients treated 31,579 migraine attacks (average 15 per patient), for up to 1 year. Twenty-six percent of attacks treated with a single zolmitriptan 5-mg dose were associated with at least one adverse event (24% treated with two doses). The most frequent adverse events included asthenia (14% of patients), nausea (12%), somnolence (10%), dizziness (11%), and paresthesia (11%). The rank order of the most common adverse events was not influenced by sex, age, or number of zolmitriptan doses taken and was similar between attacks 1 and 45. The majority of adverse events (59%) occurred within 2 hours of dosing, were of either mild (59%) or moderate (35%) intensity, of 4 hours' duration or less (67%), and required no further action (94%). Following an initial 5-mg dose of zolmitriptan, the 2-hour headache response rate (reduction in headache pain from moderate or severe before treatment to mild or no pain at 2 hours posttreatment) was 81% in patients treating moderate and severe attacks (19,639 of 24,161). Patients were pain-free at 2 hours in 55% of all attacks (16,510 of 29,808). The efficacy of zolmitriptan was not influenced by age, sex, weight, use of prophylactic antimigraine medication, or association of attacks with menstruation. Analysis of the overall population and a subgroup who treated 30 or more migraine attacks showed that zolmitriptan was consistently effective across attacks. Overall, 67% of patients who treated five or more attacks reported zolmitriptan to be effective in 80% to 100% of attacks. Zolmitriptan produced meaningful migraine relief and improvement in normal activity impairment in 73% and 78% of moderate and severe attacks, respectively. Patients treated recurrence of moderate or severe headache with a second zolmitriptan dose in 32% of attacks which responded to the first dose within 2 hours. Where required, a second zolmitriptan 5-mg dose for treatment of recurrence produced a headache response rate of 90% at 2 hours postdose. Thus, zolmitriptan 5 mg (plus an optional second 5-mg dose for treatment of recurrence) is well tolerated and effective in the acute treatment of multiple migraine attacks over periods up to 1 year.