University of Michigan Law School Scholarship Repository
Abstract
As described by Professors Dan Burk and Mark Lemley, drugs are[...] special because of the low number of patents per product: In some industries, such as chemistry and pharmaceuticals, a single patent normally covers a single product. Much conventional wisdom in the patent system is built on the unstated assumption of such a one-to-one correspondence. Although many have repeated this one-patent, one-drug assumption, there has been little empirical analysis of how many patents actually protect each drug. In fact, most small-molecule drugs are protected by multiple patents. The average was nearly 3.5 patents per drug in 2005, with over five patents per drug for the best-selling pharmaceuticals; these numbers have increased over time. This Note contains a detailed empirical examination of how many patents cover FDA-approved small-molecule drugs, what factors influence the number of patents, and the implications of having multiple patents on a drug. In particular, follow-on patents have important implications for the growing number of universities and other public-sector research institutions that want to make their patented medical technologies accessible in developing countries. For example, if a university chooses not to patent a new drug molecule in India but subsequently licenses its U.S. patent on that molecule to a pharmaceutical company that files a follow-on method-of-treatment patent in India, then Indian generic manufacturers will be unable to produce the drug. These results are important for the ongoing debate about public-sector patenting. The widespread prevalence of follow-on patents also has implications beyond the university context, since these patents generally extend the patent life of a drug. This Note proceeds in four Parts. Part I examines the role of patents in drug development and the regulatory environment under the Hatch-Waxman Act. Part II discusses ways in which follow-on patents can impede socially responsible licensing efforts by universities and other public-sector institutions. Part III presents an empirical analysis of drug patent data, which shows that the number of patents per drug has increased over time, and examines factors that have influenced this trend. The data also reveal that drugs with public-sector patents are more likely to have follow-on patents than drugs without public-sector patents. However, because many of these follow-on patents are additional public-sector patents, the drugs with public-sector patents are actually less likely to have private-sector follow-on patents. Finally, Part IV describes a table of detailed patent information for eighteen recently approved drugs with both public- and private-sector patents and discusses the implications of these results for university patenting and licensing. Over half of public-sector drugs still have private-sector patents, so public-sector institutions that want their drugs to be generically produced for patients in developing countries will need to request licensing terms that prevent private-sector patents from blocking patient access
