Frequency of first generic drugs approved through "skinny labeling," 2021 to 2023.

Background: Brand-name drug manufacturers receive a market exclusivity period following US Food and Drug Administration (FDA) approval, which can be extended through obtaining additional patents such as method-of-use patents. The skinny labeling pathway, in which the FDA approves generic prescriptions that carve out patent-protected indications from their labeling, has helped promote competition and timely market entry of low-cost generic prescriptions for many decades.

Objective: To determine how the use of the skinny labeling pathway by generic prescription drug manufacturers has changed in recent years.

Methods: Based on FDA-curated lists, we assessed the proportion of FDA-approved first generic prescriptions using the skinny labeling pathway from 2021 to 2023. We also examined whether the use of the pathway changed after a 2021 federal court decision (GlaxoSmithKline v. Teva) increased the risk of legal liability for generic manufacturers marketing skinny label generic prescriptions.

Results: From 2021 to 2023, 42.9% of 21 susceptible brand-name drugs required a skinny labeled generic prescription, including 5 (56%) in 2021, 3 (43%) in 2022, and 1 (20%) in 2023.

Conclusions: Previous literature found 43% of brand-name drugs experienced skinny labeling generic prescription competition in a 2015-2019 sample, which is consistent with the rate of skinny labeled generic prescription entry early in our sample. Then, the proportion of first generic prescriptions approved with a skinny label decreased annually from 2021 to 2023. Applying this 2021 GlaxoSmithKline v. Teva methodology in subsequent years can help determine whether the judicial decision has had a sustained chilling effect on generic prescription manufacturers' use of skinny labeling, resulting in delayed generic prescription competition as a result of fewer generic prescriptions entering the market.