Introduction: Several studies confirm that botulinum toxins type A (BTX-A) are effective for reducing facial lines caused by hyperactive muscles. Two different commercial types of BTX-A currently available are BTX-A-1 (Botox) and BTX-A-2 (Dysport). This paper reports further comparison of dosing, efficacy and safety.
Methods: Sites treated: glabellar, horizontal forehead lines and crow's feet. Different dilutions and dosages were studied with BTX-A-1 and BTX-A-2. The reduction of facial lines was evaluated by investigators and patients. Computerized photographic numerical assessment was also studied in determining the efficacy of BTX-A for crow's feet lines.
Results: Study 1: Injecting glabellar lines at doses of BTX-A-1 (30 units) and BTX-A-2 (75 units) (2.5:1 ratio BTX-A2:BTX-A1) showed similar efficacy. Study 2: BTX-A-2 (256 units total) was significantly more effective than BTX-A-1 (64 units total) (i.e. a dose ratio of 4:1) for upper face lines. No differences in the side-effect profiles between the two toxins were observed in either study. Study 3: A computerized photographic numerical assay was an objective assessment of crow's feet severity. Using a dose ratio of BTX-A-2 to BTX-A-1 of 3:1 showed a trend towards BTX-A-2 superiority.
Conclusion: Two different botulinum toxins type A were shown to be effective and safe for hyperfunctional facial lines. The choice of dose, dilution and placement is critical for each individual toxin. Computerized photography gave numerical severity scores of crow's feet severity.