Exploring the Relationship between Drug Patent Life and Drug Approvals

OBJECTIVES: The objectives of this study were to assess whether pharmaceutical companies focus their R&D activities on therapeutic categories with longer patent life and to examine the impact of drug regulatory changes on the effective patent life and the number of New Molecular Entities (NMEs) approved by the Food and Drug Administration (FDA) in the period of 1980 to 2009.

DATA AND METHODS: Data derived from the electronic version of FDA ‘Approved Drug Products with Therapeutic Equivalence Evaluations' (i.e. Orange Book) over the period of 1980-2009. The study used simple linear regression models to assess the impact of the minimum and maximum effective patent life on the NMEs approved in the study period. Regression models were analyzed for the entire study period, the 80s, 90s, and 2000s and the pre and post implementation of the Prescription Drug User Fee Act (PDUFA) (1992), the Uruguay Round Agreements Act (URAA) (1994) and the Food and Drug Administration Modernization Act (FDAMA) (1997). Differences between periods were assessed using t-test. Significant level was set at 0.05.

RESULTS: The FDA approved 739 NMEs during the study period. The number of NMEs approved increased from the 1980s (n=217) to the 1990s (n=311) and decreased during the 2000s (n=211). The average minimum effective patent life was 10.78±4.65 years and the average maximum effective patent life was 14.75±5.58 years during the study period. The average minimum effective patent life was 10.17±4.63 years in 1980s, 11.94±3.51 years in 1990s and 9.38±3.40 years in the 2000s. The average maximum effective patent life was 13.72±6.54 years in the 1980s, 15.46±4.07 years in the 1990s and 13.95±3.66 years in the 2000s. The effective patent life of a therapeutic class did not explain the number of NMEs approved in the category in the study period (p ≥0.09). The NMEs approved significantly increased after the implementation of PDUFA (p =0.04) and URAA (p =0.03). The maximum patent life increased significantly after PDUFA implementation (p =0.01).

CONCLUSIONS: The effective patent life alone did not explain the number of NMEs of a therapeutic class approved by the FDA. Federal regulation had an impact on the effective patent life and on the number of NMEs approved by the FDA in the study period.