FDA Approves Once-Weekly Gwyn Lo Contraceptive Patch

The US Food and Drug Administration (FDA) has approved norelgestromin and ethinyl estradiol transdermal system (Gwyn Lo), a once-weekly combined hormonal contraceptive (CHC) patch, for women of childbearing potential with a body mass index (BMI) < 30 kg/m² who are appropriate candidates for CHC.¹

Viatris announced the approval on July 29, 2026, citing contraceptive efficacy, a well-characterized safety profile, and robust adhesion in prior clinical study.¹ Gwyn Lo delivers norelgestromin 220 mcg/day and ethinyl estradiol 20 mcg/day and is expected to reach the US market later this year.¹

The approval was granted under the FDA's 505(b)(2) pathway and builds on Viatris' existing transdermal drug delivery portfolio in women's health.¹

Gwyn Lo Efficacy and Adhesion in the Phase 3 Luminous Study

The approval was supported by the phase 3 Luminous Study, which evaluated contraceptive efficacy, safety, and adhesion of Gwyn Lo over a year-long treatment period.¹ The efficacy evaluable population comprised women aged 18 to 35 years, including a subgroup with BMI ranging from 25 to < 30 kg/m², for whom the approved label carries no BMI-based limitation of use.¹ The primary efficacy endpoint was the Pearl Index (PI), defined as the number of pregnancies per 100 woman-years of exposure, which was 4.14 (95% CI, 2.77-5.95) in the efficacy evaluable population.¹

Patch adhesion was assessed across 39,790 transdermal systems applied during the trial, with only 1.3% fully detaching.¹ An additional 4 phase 1 studies further examined delivery consistency under varying application sites and conditions, including sauna, whirlpool, treadmill exercise, and cold-water bath, and demonstrated consistent drug delivery across these settings.¹ Gwyn Lo is applied once weekly for 3 consecutive weeks followed by 1 patch-free week.¹

Gwyn Lo Safety Profile and Cycle Control Data

Cycle control improved across the treatment period, according to Viatris.¹ Rates and duration of unscheduled bleeding or spotting decreased from 34.5% and a mean of 3.2 days in Cycle 1 to 20.0% and 2.4 days by Cycle 13.¹ Viatris presented this trend as evidence of improving tolerability with continued use.¹

The most common adverse reactions occurring in ≥ 2% of participants 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%).¹ Viatris characterized the overall safety profile as well-characterized based on the Luminous Study data.¹ The release did not report any new safety signals beyond these known CHC-associated events.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," Philippe Martin, Viatris Chief R&D Officer, said in a statement.¹ "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."

References

1. Viatris Inc. Viatris announces FDA approval of Gwyn Lo (norelgestromin and ethinyl estradiol transdermal system). Published July 29, 2026. Accessed 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. ClinicalTrials.gov. Study evaluating contraceptive efficacy, safety, and adhesion of a norelgestromin/ethinyl estradiol transdermal patch (NCT05139121). Accessed July 29, 2026. https://clinicaltrials.gov/study/NCT05139121