OnabotulinumtoxinA for treatment of chronic migraine: Results from the double-blind, randomized, placebo-controlled phase of the PREEMPT 2 trial

This is the second of a pair of studies designed to evaluate the efficacy and safety of onabotulinumtoxinA (BOTOX®) for prophylaxis of headaches in adults with chronic migraine.

PREEMPT 2 was a phase 3 study, with a 24-week, double-blind, placebo-controlled phase, followed by a 32-week, open-label phase. Subjects were randomized (1:1) to injections of onabotulinumtoxinA (155U–195U; n = 347) or placebo ( n = 358) every 12 weeks for two cycles. The primary efficacy endpoint was mean change in headache days per 28 days from baseline to weeks 21–24 post-treatment.