Frequency and Nature of Generic "Design Around" of Brand-Name Patents in the United States

Brand-name drug manufacturers commonly receive numerous patents covering their products to try to block price-lowering competition from generic manufacturers. However, under US law, generic manufacturers can develop clinically interchangeable versions that avoid some brand-name drug patents by creating new formulations that "design around" existing patents or skinny labels that do not include patented methods of use. Since generics nearly always lead brand-name manufacturers to file lawsuits, we sought to characterize the types of generic design around strategies by examining patent infringement litigation from 2000 to 2023. We used Lex Machina to identify cases and manually reviewed them to determine the drug involved and how generics designed around the patent. The cohort consisted of 153 cases involving 114 products. Twenty-eight cases (18%, 95% CI: 13-25) involved changes to how the product was used, including skinny labeling. The other 125 cases (82%, 95% CI: 75-87) involved alterations to the physical product or packaging. The most common physical change was to the formulation of the product (73 cases (48%, 95% CI: 40-56)). Changes to the active ingredient (18 cases (12%, 95% CI: 8-18)) or manufacturing process (15 cases (10%, 95% CI: 6-16)) were also common. Tablets and capsules were overrepresented in our cohort as compared to all approved drugs (the June 2023 Orange Book had 41% tablets and capsules, 95% CI: 39%-42%, P < 0.001), as were extended or delayed-release formulations (making up 23/57 (40% [95% CI: 29-53]) of the tablet or capsule products in our cohort vs. 324/886 in the Orange Book, 15% [95% CI: 14-17], P < 0.001).