Patent term restoration for top-selling drugs in the United States.

Patents temporarily protect brand-name drugs from generic competition, but some of the 20-year patent term is used up before marketing approval. To compensate for patent life lost to clinical testing and regulatory review, current law provides patent term restoration (PTR) of up to 5 years. Examining 170 top-selling drugs with a first generic equivalent approved between 2000 and 2012, we found that 49% (83 drugs) received a PTR extension (median extension: 2.75 years) yielding a median total exclusivity period of 13.75 years, compared with 10.0 years for the 87 nonextended drugs. Because PTR substantially prolongs market exclusivity periods, policies that extend non-patent exclusivity periods (which generally run concurrently with patent exclusivity) for less than the extended patent terms of drugs will have little practical impact.