Botulinum toxin A in the treatment of glabellar lines: scheduling the next injection

A single intramuscular treatment with botulinum toxin A (BoNT-A) into the facial muscles underlying glabellar rhytids has been shown to effectively attenuate or totally erase these lines for at least 3 months.

We sought to evaluate the optimal time for a second injection of BoNT-A (Dysport, Ipsen).

One hundred patients with moderate to severe glabellar rhytids at rest were randomized to a first, double-blind injection of 50 U of BoNT-A (n = 50) divided into 5 intramuscular sites, or placebo (n = 50). At monthly intervals between Month 3 and Month 6, the patient and the investigator consensually decided to repeat the injection with open-label BoNT-A in both groups. The main outcome was the time between the first and second injections. Responder ratings (mild or no glabellar lines) after the first and second injections, patient satisfaction, and safety were also assessed.

At Months 3 and 4 after the first injection, the cumulative percentage of patients having a second injection was lower in the BoNT-A group compared to the placebo group, with a significant difference at Month 4. Following the first double-blind injection, responder rates were significantly higher in BoNT-A group (up to 75%) compared to placebo up to Month 4, and a large majority of patients were significantly satisfied with the BoNT-A treatment at Month 4 (75% satisfied and completely satisfied versus 9.1% with placebo) and Month 5 (86.7% versus 0%, respectively). Headache was the most frequent adverse event in the BoNT-A group (10% versus 6% in the placebo group). No blepharoptosis was reported.

The effectiveness of 50 U of BoNT-A was confirmed for the treatment of glabellar lines. A second injection was sought within 3 to 4 months by most patients and investigators. Both injections were safe.