Intended for healthcare professionals


Improving the quality of US drug patents through international awareness

BMJ 2022; 377 doi: (Published 17 May 2022) Cite this as: BMJ 2022;377:e068172
  1. Doni Bloomfield, postdoctoral research fellow,
  2. Zhigang Lu, research scientist,
  3. Aaron S Kesselheim, professor of medicine
  1. Program on Regulation, Therapeutics, and Law (PORTAL), Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
  1. Correspondence to: A Kesselheim akesselheim{at}

Doni Bloomfield and colleagues propose a novel approach to improving US patent quality by flagging patent applications for additional scrutiny when matching applications have been discontinued abroad

Prescription drugs are one of the most prevalent and useful interventions in medicine, accounting for 13.7% of US healthcare expenditure.1 Per capita spending on drugs in the US is greater than in comparable high income countries, driven by the high prices of brand name drugs (recently approved medicines sold by a single manufacturer and typically protected from direct competition by patents).2 When a brand name drug’s patents and regulatory protections expire, its market exclusivity ends, meaning that generic or biosimilar manufacturers can sell their versions of the product, often at substantially lower prices. This leads to reductions in overall spending and wider patient access to the medicine.

Because market exclusivity is central to their revenue streams, brand name drug manufacturers have developed strategies to delay generic entry. Under US law, some drug patents can be used to automatically delay generic manufacturers from entering the market.3 Brand name drug manufacturers thus have an interest in securing multiple patents to create a “patent thicket” protecting their product.45 Some companies have obtained dozens of secondary patents on their products—patents that protect aspects of a drug other than its novel active ingredient.4 Such patents can, for example, protect modified compounds, formulations, and methods of use, and in one case even protected the addition of cotton candy and peppermint flavouring to an HIV drug.6 To compete with patented treatments, generic or biosimilar manufacturers must seek to either design drugs to avoid infringement claims or sue to invalidate individual patents.6 Secondary patents are common and often the subject of court battles. One 2021 working paper found that between 2000 and 2018 …

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