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.

专利可以暂时保护品牌药物免受仿制药的竞争，但是20年专利期限中的某些期限在上市许可之前就用光了。为了补偿因临床测试和监管审查而损失的专利寿命，当前法律规定专利期限的恢复（PTR）最长为5年。在对2000年至2012年间批准的首个通用等效药品中的170种畅销药进行检查后，我们发现49％（83种药物）获得了PTR延期（中位延期：2.75年），平均总独占期为13.75年，而中值为10.0年为87种非扩展药物。由于PTR大大延长了市场独占期，因此将非专利独占期（通常与专利独占并发运行）延长到少于药品的延长专利期限的政策将几乎没有实际影响。