A prospective, double-blind, randomized, parallel-group, dose-ranging study of botulinum toxin type A in female subjects with horizontal forehead rhytides

BACKGROUND. Botulinum toxin type A is used cosmetically to improve facial lines, but it has not been thoroughly investigated for the treatment of horizontal forehead rhytides. OBJECTIVE. To compare the efficacy and safety of three doses of botulinum toxin type A in females with horizontal forehead rhytides and to establish whether the response rate and the duration of response are dose dependent. METHODS. Fifty-nine female patients with horizontal forehead rhytides scoring 2 (moderate) or 3 (severe) on the facial wrinkle scale (FWS) were randomly assigned to receive 16, 32, or 48 U of botulinum toxin type A (Botox, Botox Cosmetic; Allergan, Irvine, CA), which was administered to eight injection sites. Half of the dose was administered to the brow depressors and the other half to the elevators. Wrinkle severity was assessed by the investigator and patient using the FWS at baseline, at Weeks 2 and 4, and then every 4 weeks for 48 weeks. RESULTS. Improvements in horizontal rhytides were observed in all dosage groups. Significant dose-response trends were observed for rate of improvement at maximum brow elevation (53% in the 48-U group vs. 15% in the 16-U group at 16 weeks) and rate of relapse to baseline (35% in the 48-U group vs. 75% in the 16-U group at 16 weeks) by a trained observer. CONCLUSION. Higher botulinum toxin type A doses resulted in greater efficacy and longer duration of effect in the reduction of horizontal rhytides.