Topical application of a new formulation of oxybutynin hydrochloride 20% lotion for 4 weeks was superior to placebo in reducing the volume of sweat in patients with primary palmar hyperhidrosis, according to results of a phase 3 trial published online March 27, 2023 in the Journal of American Academy of Dermatology.¹

Primary palmar hyperhidrosis is characterized by excessive sweating of the palms, which occurs not due to temperature, but as a result of mental stress or some emotional stimulus and adversely affects the quality of life of the patient. The cause remains unknown.

The efficacy of 20% oxybutynin hydrochloride lotion in decreasing the sweat volume in 144 patients, aged 34.1 years (mean), with primary palmar hyperhidrosis was compared with 140 placebo-recipients, aged 35.7 years (mean) in this study from Japan. The patients were recruited from 21 clinics in Japan from October 2020 to February 2021. The patients were instructed to apply 20% oxybutynin hydrochloride or placebo once in a day on both palms for 4 weeks. A decrease in sweat volume by ≥50% from baseline was the primary endpoint of the study. The secondary endpoints were Hyperhidrosis Disease Severity Scale (HDSS) scores and Dermatology Life Quality Index (DLQI) scores.

The percentage of patients who met the primary endpoint at the end of the study was higher among those receiving 20% oxybutynin hydrochloride lotion compared to the placebo-recipients; ~53% vs 24.3%, respectively with treatment difference of 28.5%. The improvement in the HDSS score by ≥1 point was higher among those who were being treated with 20% oxybutynin hydrochloride lotion compared to those treated with placebo; 67.4% vs 42.9%, respectively with treatment difference of 24.5%. The improvement in HDSS scores was evident within 2 weeks of starting treatment. However, the DLQI scores were comparable between the two groups. Most adverse events that occurred were mild in nature. No serious adverse events that merited discontinuation of treatment were reported during the study.

These findings indicate that 20% oxybutynin hydrochloride is a potential safe and effective treatment for primary palmar hyperhidrosis, which is a disabling and a very challenging condition to treat.

Reference

1. Fujimoto T, et al. A novel lotion formulation of 20% oxybutynin hydrochloride for the treatment of primary palmar hyperhidrosis: A randomized, placebo-controlled, double-blind, phase III study in Japan. J Am Acad Dermatol. 2023 Mar 27;S0190-9622(23)00511-X. doi: 10.1016/j.jaad.2023.03.025