311C90: long-term efficacy and tolerability profile for the acute treatment of migraine. International 311C90 Long-Term Study Group.

311C90 (Zomig; zolmitriptan) is a novel, selective serotonin (5HT)1B/1D receptor agonist with both central and peripheral activity, now in late-stage clinical development for acute oral treatment of migraine. Several studies have demonstrated the tolerability and efficacy of 311C90 in the treatment of a single migraine headache. The objectives of this open-label study were to assess the tolerability and efficacy of repeated doses of 5 mg of 311C90 for acute treatment of multiple attacks for up to 1 year. Patients were allowed to treat as many migraine headaches (mild, moderate, or severe) as desired with an initial dose. A second 5-mg dose could be used to treat recurrence should it develop. Safety assessments included ECG, the frequency, intensity, and duration of adverse experiences, and routine hematology, urinalysis, and clinical chemistry parameters. Efficacy assessments included headache severity at 2 hours (i.e., severe, moderate, mild, or none), the proportion of patients pain-free at 2 hours, the use of a second tablet to treat headache recurrence if it developed, and the consistency of these findings over time. The efficacy profile and the nature/incidence of adverse events reported appear to be consistent with previous 311C90 studies. The dosing regimen was well tolerated during multiple exposures. Notably, headache response rates were consistently good after both initial and repeated exposure (> 80% across 1 to 30 attacks). For 67% of patients who treated at least five attacks, 311C90 was effective 80 to 100% of the time.