A centuries-old drug used to treat excruciating gout pain had cost just pennies a tablet—until last year. Now, the retail price has skyrocketed to more than $5 and some of the manufacturers have ceased production amid a battle over marketing rights.

The tale of how this common gout drug, colchicine, became the costlier branded drug Colcrys offers a window into the Byzantine world of drug pricing. The price rise is a consequence of a Food and Drug Administration effort to improve the safety of long-used but unapproved drugs, with a trade-off often made between drug affordability and safety.

In July 2009, a Philadelphia drug maker received FDA approval to exclusively market colchicine for gout attacks for three years. The company, URL Pharma Inc., was taking advantage of a push to bring medicines predating the FDA, like colchicine, under the agency's regulatory umbrella. The FDA offers exclusive marketing rights if a drug maker conducts clinical trials.

URL Pharma had commissioned studies that confirmed its colchicine product's safety and efficacy, while demonstrating it should be taken at a lower dose than typical and not used with certain other medicines. The company is marketing its drug as Colcrys—and the retail cost averages $5 per pill, according to DestinationRx, a health-care data provider.

URL is also suing longtime manufacturers of unapproved colchicine, saying the companies are now illegally marketing their products. Some of the companies are fighting the lawsuits. Some themselves have raised prices—including one increase of just under a dollar per tablet to $1.17, according to DestinationRx. The higher price for Colcrys was first reported by Kaiser Health News.