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Importance: Brand-name drugs are sold at high prices in the US during market exclusivity periods protected by patents. Multiple overlapping patents protecting a drug are known as patent thickets and can effectively delay the emergence of price-lowering generic competition for many years., Objective: To evaluate the composition of patent thickets of 10 top-selling prescription drugs in the US and compare the characteristics of drug patents filed during development with those filed on these products after US Food and Drug Administration (FDA) approval., Design and Setting: This cross-sectional study examined US patent thickets of the 10 prescription drugs with the highest US net sales revenue in 2021 using information on issued patents and patent applications as of June 30, 2022, obtained from a public database by the Initiative for Medicines, Access, and Knowledge. Data were analyzed from September 2022 to June 2023., Main Outcomes and Measures: Prevalence of patents filed before and after FDA approval; types of claims present in issued patents (ie, chemical composition, method of use, process or synthesis, formulation, and delivery device); and patent thicket density (number of active patents at a given time)., Results: The 10 top-selling prescription drugs in the US for 2021 included 4 small-molecule drugs and 6 biologics. These 10 drugs were linked to 1429 patents and patent applications: 742 (52%) issued patents, 218 (15%) pending applications, and 469 (33%) abandoned applications. Almost three-quarters of patent applications (1028 [72%]) were filed after FDA approval. The postapproval proportion was higher for biologics (80%) than for small-molecule drugs (58%). Postapproval filing of patent applications peaked in the first 5 years after FDA approval for small-molecule drugs and 12 years after FDA approval for biologics. Of 465 patents issued for applications filed after FDA approval, 189 (41%) had method of use claims, 127 (27%) had formulation claims, and 103 (22%) had process or synthesis claims, while 86 (19%) had chemical composition claims and 46 (10%) had device claims. Patent thicket density peaked 13 years after FDA approval, at which time these 10 drugs were protected by a median (IQR) of 42 (18-83) active patents, 66% of which were filed after FDA approval., Conclusions and Relevance: This study found that among the 10 top-selling prescription drugs in the US in 2021, patents filed after FDA approval and containing claims covering aspects other than the active ingredient of the drug contributed to patent thickets. Scrutiny of patent applications and of patents filed after FDA approval is needed to facilitate timely generic or biosimilar competition.

Importance: Glucagon-like peptide 1 (GLP-1) receptor agonists were first approved for the treatment of type 2 diabetes in 2005. Demand for these drugs has increased rapidly in recent years, as indications have expanded, but they remain expensive., Objective: To analyze how manufacturers of brand-name GLP-1 receptor agonists have used the patent and regulatory systems to extend periods of market exclusivity., Evidence Review: The annual US Food and Drug Administration's (FDA) Approved Drug Products With Therapeutic Equivalence Evaluations was used to identify GLP-1 receptor agonists approved from 2005 to 2021 and to record patents and nonpatent statutory exclusivities listed for each product. Google Patents was used to extract additional data on patents, including whether each was obtained on the delivery device or another aspect of the product. The primary outcome was the duration of expected protection from generic competition, defined as the time elapsed from FDA approval until expiration of the last-to-expire patent or regulatory exclusivity., Findings: On the 10 GLP-1 receptor agonists included in the cohort, drug manufacturers listed with the FDA a median of 19.5 patents (IQR, 9.0-25.8) per product, including a median of 17 patents (IQR, 8.3-22.8) filed before FDA approval and 1.5 (IQR, 0-2.8) filed after FDA approval. Fifty-four percent of all patents listed on GLP-1 receptor agonists were on the delivery devices rather than active ingredients. Manufacturers augmented patent protection with a median of 2 regulatory exclusivities (IQR, 0-3) obtained at approval and 1 (IQR, 0.3-4.3) added after approval. The median total duration of expected protection after FDA approval, when accounting for both preapproval and postapproval patents and regulatory exclusivities, was 18.3 years (IQR, 16.0-19.4). No generic firm has successfully challenged patents on GLP-1 receptor agonists to gain FDA approval., Conclusions and Relevance: Patent and regulatory reform is needed to ensure timely generic entry of GLP-1 receptor agonists to the market.