New Drug Formulations and Their Respective Generic Entry Dates

J Manag Care Spec Pharm. 2019 Feb;25(2):218-224. doi: 10.18553/jmcp.2019.25.2.218.


Background: After new prescription drugs reach the market, manufacturers sometimes create modified versions of them. These new formulations can expand patient treatment options, but they may also be protected by later-expiring patents or data exclusivities, which can lead to later generic entry for the new formulations compared with the original product.

Objective: To quantify how frequently manufacturers introduce new formulations of existing drugs and how often these new formulations earn additional years of market exclusivity beyond that of the original product.

Methods: Using a cohort design and FDA databases, we assessed how frequently manufacturers introduced new formulations of 17 new small-molecule drugs approved in 2002 and when generic entry for the new formulations and original product occurred.

Results: Through 2017, nine (53%) drugs approved in 2002 had been connected to 21 new formulations, most (11/21, 53%) introduced before 2007. Generic entry was observed in 6 of 9 (67%) cases and occurred more than 2 years later for the new formulations in 3 of the cases.

Conclusions: Our results suggest that the introduction of new formulations of brand-name drugs occurs in about half of cases and sometimes provides manufacturers with a lengthy period of additional market exclusivity beyond that of the original product.

Disclosures: This work was funded by the Laura and John Arnold Foundation. Kesselheim and Sarpatwari also receive support from the Harvard-MIT Center for Regulatory Science and the Engelberg Foundation. Beall has nothing to disclose.

MeSH terms

  • Cohort Studies
  • Databases, Factual
  • Drug Design
  • Drug Industry / economics
  • Drug Industry / statistics & numerical data*
  • Drugs, Generic / administration & dosage
  • Drugs, Generic / economics*
  • Humans
  • Patents as Topic / statistics & numerical data*
  • Prescription Drugs / administration & dosage
  • Prescription Drugs / economics*
  • Time Factors
  • United States
  • United States Food and Drug Administration


  • Drugs, Generic
  • Prescription Drugs