CMS followed the guidelines specified in the Inflation Reduction Act when selecting the drugs for the first round of price negotiations. The first thing CMS considers is which qualifying drugs are single-source drugs. Single-source drugs have been FDA-approved and on the market for at least seven or 11 years for biologics (like vaccines), without generic or biosimilar competitors. CMS also considered which drugs had the highest total covered costs under Medicare Part D. This data was collected from June 1, 2022, through May 31, 2023.