In addition, 75% of patients who received injections of botulinum toxin type A reported that the injections eliminated or significantly reduced the impairment of daily activities associated with hyperhidrosis after each of the treatments.

"The take-home message is that this is a sustainable therapy," said lead investigator and presenter Dee Anna Glaser, MD, Professor of Dermatology, St. Louis University Medical School, St. Louis, Missouri, United States. "Now we know it works just as well at 3 years as it did on the first use."

For their 3-year, open-label extension study, Dr. Glaser and colleagues enrolled 147 subjects who had completed a previous 1-year, randomized controlled trial of botulinum toxin type A at a dose of 50 U/axilla or 75 U/axilla or placebo.

Patients were then treated once with a 50-U/axilla injection. Researchers evaluated the subjects at weeks 1, 4, and 8, and monthly thereafter.

Subjects were eligible for reinjection 8 weeks after each treatment if symptoms persisted or recurred. They used the 4-point Hyperhidrosis Disease Severity Scale (HDSS) to rate the level of interference with daily activities of their hyperhidrosis symptoms. The researchers measured sweat production using gravimetric analysis using filter paper to quantify the secretion of sweat.

A 12-month interim analysis of the extension study included 1 year of data from the original study plus 1 year of data from the extension study.

The results show that 83% of subjects had at least a 2-grade improvement from baseline in HDSS score at week 4 after the first botulinum injection in the extension study, and 75% measured the same level of improvement at week 8.

Among subjects needing a second or third treatment, 81% and 78%, respectively, achieved at least a 2-grade improvement in HDSS score 4 weeks post-injection.

Fifteen percent of patients required four or more botulinum toxin type A treatments.

The researchers reported that mean gravimetric sweating was significantly decreased following botulinum toxin type A treatment with 75% reduction in sweating from baseline values 4 weeks after receiving treatment among 82%, 79%, and 79% of patients in botulinum sessions 1, 2, and 3, respectively.

"No serious treatment-related adverse events were reported and no patients discontinued the study because of adverse events," the authors noted.

The study received financial support from Allergan, Inc.


[Presentation title: Efficacy and Safety of Repeated Treatments With Botulinum Toxin Type A for Primary Axillary Hyperhidrosis: Results From 3 Years of Longitudinal Data. Abstract P563]

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