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ABSTRACT Pharmaceutical manufacturers rely on patents to protect their intellectual property and often seek to extend market exclusivity for their products to maximize their return on investment. One method is by obtaining patents on features other than the original active drug ingredient, including secondary patents on alternate formulations of the drug or on methods of administration. This article examines how secondary patents can extend market exclusivity and thus delay generic competition, using as an example two key antiretroviral drugs for the management of HIV: ritonavir (Norvir) and lopinavir/ritonavir (Kaletra). We identified 108 patents, which together could delay generic competition until at least 2028-twelve years after the expiration of the patents on the drugs' base compounds and thirty-nine years after the first patents on ritonavir were filed. Some of the secondary patents that were reviewed were found to be of questionable inventiveness. We argue that increased transparency for existing patents, stricter patentability standards, and increased opportunities to challenge patent applications and patents could reduce inappropriate market exclusivity extensions on brand-name drugs and open the door to lower-cost generics.
The process of developing new prescription drugs has long been intertwined with the US patent system. To earn a patent, an invention must be novel and constitute what patent law refers to as a "nonobvious" advance over current knowledge in the field. Pharmaceutical manufacturers rely on patents to protect their intellectual property: Patents provide market exclusivity during the patent term, which is twenty years from the patent application date. During this competition-free period, manufacturers charge higher prices for their products to recoup their initial investment in development and testing. 1 After this period, less expensive generic versions can come on the market and become widely available.2
Pharmaceutical manufacturers therefore have an incentive to extend market exclusivity for their products as long as possible.3 One common strategy is to obtain additional patents beyond the original patents that protect the drug's underlying active ingredient and disease targets. These "secondary" or "later-issued" patents may protect peripheral features of the product (such as a tablet's coating),4 metabolites or alternative crystalline forms of the product,5 or methods of use (such as a method of treating disease).6 In the pharmaceutical sector, this practice is called "life-cycle management;" it is also sometimes referred to...