The U.S. Department of Health and Human Services last week clarified when hospitals are allowed to buy socalled orphan drugs at sharply discounted prices, but it left open questions for drug manufacturers about the risk of being prosecuted for off-label promotion of them.

The drugs, which are for rare diseases and named after the small “orphan” populations of fewer than 200,000 people they’re designed to treat, are among the most expensive on the market.

Originally published in Thomson Reuters on 7/31/13.