Changes in the Number of Continuation Patents on Drugs Approved by the FDA

Brand-name pharmaceutical manufacturers often sustain high prices in the US by obtaining patents that delay generic competition. Patents may be obtained on active ingredients and “secondary” features of drugs such as new formulations and methods of use.1,2 One legal strategy to obtain large numbers of secondary patents is via a special type of application to the US Patent and Trademark Office (USPTO), called a continuation, in which a patent holder adds new applications to a prior submission by offering minor clarifications or additions without substantial change to the underlying invention. Continuation patents can deter competition by increasing uncertainty for generic manufacturers, since they must avoid infringing (or must challenge) evolving patent claims on drugs.

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