Pooled analysis of the safety and tolerability of onabotulinumtoxinA in the treatment of chronic migraine

Background and purposeOnabotulinumtoxinA was effective and well tolerated for prophylaxis of headache in patients with chronic migraine (CM) in two randomized, double-blind, placebo-controlled, phase 3 trials. To further assess the safety and tolerability of onabotulinumtoxinA in CM prophylaxis in adults, the pooled safety data from four double-blind, placebo-controlled trials were analyzed. MethodsThe pooled analysis included two phase 2 and two phase 3 double-blind, placebo-controlled trials. The safety population was 2436 patients, 1997 of whom received 1 dose of onabotulinumtoxinA. The studies shared similar dosing intervals (approximately 12weeks) with doses between 75 and 260U. Safety assessments included adverse events (AEs), physical examination and clinical laboratory tests. ResultsOnabotulinumtoxinA was safe and well tolerated, with a low discontinuation rate (3.4%) due to AEs. The majority of patients in this pooled analysis received doses between 150 and 200U, with an average of 163U per treatment cycle. Of the 1997 patients who received any onabotulinumtoxinA injections, 1455 patients (72.9%) reported at least one AE. Neck pain (12.6%) was the most common onabotulinumtoxinA-associated AE, followed by muscle weakness (8.0%), musculoskeletal stiffness (6.1%) and eyelid ptosis (4.6%). Serious AEs were infrequent, occurring in 5.4% of patients who received any onabotulinumtoxinA treatment and 3.0% of patients receiving placebo. AEs were consistent with the known tolerability profile of onabotulinumtoxinA. ConclusionsMultiple treatments with onabotulinumtoxinA at doses of 75-260U administered every 12weeks, and up to five treatment cycles, were well tolerated for the prophylaxis of headache in adults with CM.