Colchicine, a gout remedy so old that the ancient Greeks knew about its effects, used to cost about 25 cents per pill in the U.S. Then in 2010 its price suddenly jumped 2,000 percent.

That's just one of the side effects of a U.S. Food and Drug Administration plan to encourage testing of medicines that have been around longer than the modern FDA itself, and so have never gotten formal approval. Companies that do the tests are rewarded with licenses that can temporarily give them monopoly pricing power as most rivals are eased or kicked off the market. The result has been a surge in the cost of drugs used in treatments from anesthesia to heart surgery and eye operations.

It can bring big paydays for the producers. URL Pharma, the small Philadelphia drugmaker granted rights over colchicine, was bought for $800 million by Takeda Pharmaceutical Co. in 2012. Asia's biggest drugmaker has since brought in $1.2 billion in revenue from the branded drug, Colcrys, which went on the market at a wholesale price of almost $6 a pill. Takeda says testing for FDA approval made the drug safer.

Feeling the Pinch

But patients and hospitals are feeling the pinch, and politicians have begun to notice. Hillary Clinton's recent promise to address the issue sent pharmaceutical stocks plunging. Critics say the FDA plan lets entrepreneurs make windfall profits on drugs where there was never much concern about safety or efficacy.

In many cases, the program "almost had the opposite effect as intended," said Joseph Biskupiak, a professor at the University of Utah College of Pharmacy. "The only drugs that got studied are the ones that don't have a problem."

The FDA's rationale is that some drugs have never been measured against modern safety standards. The program "has been a success" that has removed dangerous drugs from the market, said Michael Levy, deputy director in the compliance office of the FDA's drug evaluation unit.