Topical Anticholinergic for Axillary Hyperhidrosis Shows Fewer Side Effects in Study

Ted Bosworth

April 27, 2021

Sofpironium bromide, a new topical anticholinergic agent, appears to be a safer version of glycopyrrolate for the treatment of axillary hyperhidrosis, according to 48-week safety and outcome data.

A structural analogue of glycopyrrolate working through the same mechanism, sofpironium bromide was developed as a retrometabolic agent. This means it is rapidly transformed into an inactive metabolite after application, reducing risk of systemic effects, study investigator Stacy Smith, MD, explained in the late-breaking research session at the American Academy of Dermatology Virtual Meeting Experience.

The anticholinergic glycopyrrolate, which currently is the most commonly used therapy for hyperhidrosis, is absorbed through the skin and excreted through the urine. The systemic exposure to the active agent after topical application explains the substantial risk of adverse effects, said Smith, a clinician and researcher affiliated with the California Dermatology and Clinical Research Institute, Encinitas.

In contrast, "sofpironium bromide is the ideal topical medication, because it has strong activity at the application site but then reduced systemic activity due to the retrometabolism," Smith said.

The 52-week data from the open-label, phase 3 trial supports the premise. In this study of 299 patients randomized to the 5% (102 patients) or 15% (197 patients) topical sofpironium bromide gel formulations, most anticholinergic adverse events were mild or moderate and transient, with complaints concentrated in the first 3 months of the trial.

"The retrometabolic pathway seems to work," Smith said. He acknowledged that the treatment-naive patients who entered the study "had to get used to the drug over time," but the data "show they did."

The phase 3 trial of sofpironium bromide, which is already approved to treat axillary hyperhidrosis in Japan, did not have a placebo control. It was focused primarily on safety, but outcomes were assessed with the Hyperhidrosis Disease Severity Measure–Axillary (HDSM-Ax).

At least a 1-point improvement in the 7-point HDSM-Ax scale, which is considered clinically meaningful, was achieved by 86.1% and 85.8% of those treated with the 5% and 15% gels, respectively. A 2-point or greater improvement at the end of the study was observed in 69.4% and 61.9%, respectively.

"The medication works well and there was improved efficacy over time. About two-thirds of the patients had at least a 2-point improvement in the HDSM-Ax score at the end of 48 weeks," Smith reported.

While response rates climbed over the course of the study, rates of adverse events fell markedly.

After 2 weeks of treatment, the proportions of patients with a treatment-related adverse event were 6% and just under 15% for the 5% and 15% topical-gel groups, respectively. At each 2-week interval when reassessed, the rates fell. By week 12, the rates were less than 2% and about 4% in the two groups, respectively.

The discontinuation rates overall for anticholinergic side effects were 3% and 8.1% for the lower and higher doses. Blurred vision accounted for the vast majority of these discontinuations in both groups. The other discontinuations, which included those for dry mouth, urinary retention, and mydriasis, occurred in one patient each. Again, discontinuations were most common in the first few months of the study.

For the total study population, mild (10.8% vs. 24%) and moderate (10.8% vs. 20.3%) side effects accounted for almost all side effects with the lower and higher doses of the topical drug. Only one patient in the low-dose group had a severe adverse event. At 6.1%, the proportion of the high-dose group with a severe adverse event was higher, but none of the adverse events were considered serious. All were transient.

These rates of adverse events are lower than those reported historically with effective doses of glycopyrrolate, Smith said.

The data presented by Smith are part of a phase 3 pivotal trials program designed to gain FDA approval. Going forward, these trials, which are enrolling patients as young as 9 years old, are expected to focus on clinical development of the 15% gel, he added.

The gel is delivered with a metered-dose pump that has an applicator, according to Brickell Biotech, the company developing the treatment in the United States. The 5% formulation was approved in Japan in September 2020, for the treatment of primary axillary hyperhidrosis.

In an interview, David M. Pariser, MD, professor of dermatology, Eastern Virginia Medical School, Norfolk, said that he believes that this drug has could be helpful if the pivotal studies confirm efficacy with a lower risk of adverse events relative to glycopyrrolate. "If it is true that, in phase 3, placebo-controlled trials, there are fewer systemic anticholinergic effects, then this drug will be very useful," said Pariser, cofounder of the International Hyperhidrosis Society and an investigator on a previously published dose-ranging, phase 2 study of sofpironium bromide.

The trial was sponsored by Brickell Biotech, which compensated Smith and other coauthors for their participation. Pariser has financial relationships with multiple pharmaceutical companies with dermatologic products, including Brickell Biotech.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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