Drug companies are allowed to be monopolists in the drugs they discover in order to

allow drug companies to charge a price that is equal to their marginal cost

Explanation:

Drug companies are allowed to be monopolists in the drugs they discover in order to allow drug companies to charge a price that is equal to their marginal cost.

When a monopolist is able to sell its product at different prices to different customers, it is likely engaging in price discrimination. The practice of selling a product to different customers at different prices when marginal cost is the same is known as price discrimination.