Botulinum A toxin for glabellar wrinkles. Dose and response

BACKGROUND: Botulinum A exotoxin injection is a well-established method for treatment of glabellar frown lines, crow's feet, and horizontal furrows of the forehead. However, there is no consensus as to the optimal dosage per injection site or the concentration of injectate to be used. OBJECTIVE: The purpose of this study was to determine the minimal effective dose per injection site to be used as well as the effect of concentration in response to treatment. RESULTS: A total of 46 subjects were divided into ten groups and injected with escalating doses and concentrations of botulinum toxin. The response and longevity of treatment were then followed on a monthly basis. A dose between 2.5-4 U per injection site (12.5-20 U total) was determined to be an effective starting dose, with a duration of 2-5 months (median 14 weeks). CONCLUSIONS: There was no statistically significant difference in safety or efficacy for concentrations ranging from 50 to 200 U/ml of botulinum toxin.