Double-blind, randomized, placebo-controlled pilot study of the safety and efficacy of Myobloc (botulinum toxin type B) for the treatment of palmar hyperhidrosis.

Background: Palmar hyperhidrosis is a problem of unknown etiology that affects patients both socially and professionally. Botulinum toxin type B (Myobloc), approved by the Food and Drug Administration for use in the treatment of cervical dystonia in the United States in December 2000, has subsequently been used effectively in an off-label indication to treat hyperhidrosis. There are sparse data, however, in the literature evaluating the safety and efficacy of BTX-B for the treatment of palmar hyperhidrosis.

Objective: We evaluated the safety and efficacy of Myobloc in the treatment of bilateral palmar hyperhidrosis. This was a double-blind, randomized, placebo-controlled study to report on the safety and efficacy of Myobloc.

Methods: Twenty participants (10 men, 10 women) diagnosed with palmar hyperhidrosis were injected with either Myobloc (5,000 U per palm) or a 1.0 mL vehicle (100 mM NaCl, 10 mM succinate, and 0.5 mg/mL human albumin) into bilateral palms (15 Myobloc, 5 placebo). The participants were followed until sweating returned to baseline levels. The main outcome measures were safety, efficacy versus placebo, and duration of effect.

Results: A significant difference was found in treatment response at day 30, as determined by participant assessments, between 15 participants injected with Myobloc and 3 participants injected with placebo. The duration of action, calculated in the 17 participants who received Myobloc injections and completed the study, ranged from 2.3 to 4.9 months, with a mean duration of 3.8 months. The single most reported adverse event was dry mouth or throat, which was reported by 18 of 20 participants. The adverse event profile also included indigestion or heartburn (60%), excessively dry hands (60%), muscle weakness (60%), and decreased grip strength (50%).

Conclusion: Myobloc proved to be efficacious for the treatment of palmar hyperhidrosis. Myobloc had a rapid onset, with most participants responding within 1 week. The duration of action ranged from 2.3 to 4.9 months, with a mean of 3.8 months. The adverse event profile included dry mouth, indigestion or heartburn, excessively dry hands, muscle weakness, and decreased grip strength.