This project aims to estimate the additional costs of market exclusivity extensions across all U.S. payers for prescription drugs from 2008 to 2018. The project will assess the impact of extended market exclusivity periods on branded or generic drug volumes and estimate the impact of exclusivity extensions on national branded and generic drug spending. To do this, the team will develop drug-specific timelines with volume and spending during three time frames: the original granted period of exclusivity, the extended period of exclusivity because of additional patents (e.g., patent thickets), and the period with generic competition. They will then model what volumes and spending would have been without the extended exclusivity period and had generic competition been allowed. The difference between this amount and the actual spending is the potential savings from patent reforms. Data sources include the U.S. Patent and Trademark Office database, the Food and Drug Administration "Orange Book," the Medicare Expenditure Panel Survey (MEPS), and SSR Health data.