Viatris Inc announced that FDA approved Gwyn Lo (norelgestromin and ethinyl estradiol transdermal system), a new combined hormonal contraceptive patch with low-dose estrogen.

The patch demonstrated contraceptive efficacy for women of childbearing potential with a body mass index below 30 kg/m² who are appropriate candidates for combined hormonal contraception.¹ The Gwyn Lo dosage is norelgestromin 220 mcg/day and ethinyl estradiol 20 mcg/day.

The approval was granted under FDA's 505(b)(2) regulatory pathway and was supported by results from the Phase III Luminous study (NCT05139121), which demonstrated contraceptive efficacy, a well-characterized safety profile, and robust patch adhesion performance.^1,2

What did the trial show?

The primary efficacy endpoint was the Pearl Index, defined as the number of pregnancies per 100 woman-years of exposure in the efficacy evaluable population of women aged 18 to 35 years, which came in at 4.14 (95% CI: 2.77 to 5.95).² The study also demonstrated robust patch adhesion under real-world conditions, with only 1.3% of the 39,790 transdermal systems applied during the year-long trial fully detaching.²

The most common adverse reactions occurring at a rate of 2% or greater during the study were application site irritation (4.8%), application site erythema (3.7%), application site pruritus (3.7%), intercycle bleeding (3.9%), heavy withdrawal bleeding (2.0%), and nausea (2.0%).² Cycle control improved over time, with rates and duration of unscheduled bleeding or spotting decreasing from 34.5% and a mean of 3.2 days in cycle 1 to 20.0% and 2.4 days by cycle 13.

Separately, data from four Phase I studies investigating various application sites and conditions demonstrated consistent drug delivery under conditions including sauna, whirlpool, treadmill exercise, and cold-water bath.¹

"Gwyn Lo will provide a discreet option for women seeking a reversible, non-invasive, once-weekly contraception patch with a low dose of estrogen," said Philippe Martin, chief R&D officer, Viatris. "Building on our expertise in transdermal drug delivery systems and legacy in women's health, we are pleased that the approved label for this new patch reflects the strength of our clinical program. This includes demonstrated efficacy in women with a BMI of 25 to less than 30 kg/m², with no BMI-based limitation of use in this population."

What is Gwyn Lo?

Gwyn Lo is a once-weekly transdermal contraceptive patch for women of childbearing potential with a BMI below 30 kg/m² who are appropriate candidates for combined hormonal contraception and who prefer a non-invasive, reversible option with a low estrogen dose.¹ The patch is applied once weekly for three consecutive weeks, followed by one patch-free week, and delivers norelgestromin and ethinyl estradiol over each seven-day wear interval.¹ The active ingredients and adhesive are contained in a matrix between a backing layer, which consists of a flexible film that provides structural support to the patch, and a release liner that protects the matrix and is removed just prior to application. Upon application to the skin, the system provides controlled delivery of norelgestromin 220 mcg/day and ethinyl estradiol 20 mcg/day throughout the wear interval.¹

What's next?

Viatris expects Gwyn Lo to be commercially available later this year and will provide additional information during its upcoming financial results call..

Sources

1. Viatris Receives U.S. FDA Approval for Gwyn Lo™, a Once-Weekly Contraceptive Patch Viatris July 29, 2026, https://www.prnewswire.com/news-releases/viatris-receives-us-fda-approval-for-gwyn-lo-a-once-weekly-contraceptive-patch-302837674.html
2. Study of the Safety and Efficacy of MR-100A-01 in Approximately 1200 Healthy Women for up to 13 Cycles National Library of Medicine Janurary 28, 2025, https://clinicaltrials.gov/study/NCT05139121