What is "most-favored nation" drug pricing and how does it work?

President Trump sent letters to 17 of the world's biggest prescription drugmakers last week calling on them to reduce prices on some products to much lower levels. The president wants these companies to provide the "most-favored nation" drug pricing for Medicare, Medicaid and commercial customers by the end of September. Paige Cunningham, national health reporter for the Washington Post, joined CBS News to discuss what "most-favored nation" drug pricing is.