Naltrexone, which is also used to help treat opiate addiction, comes in both an oral and injectable form and has few side effects. It was approved for use in alcohol addiction in 1994. Acamprosate was approved in 2004 to treat only alcohol problems. It comes as a tablet.

When naltrexone came on the market, sales teams had trouble explaining how the drug worked differently than Antabuse to the non-physician administrators who made treatment decisions in addiction clinics, addiction experts said. Many misunderstood how and for whom the drug worked. Some of that persists today.

“They got three years” of market exclusivity, said Dr. Henry Kranzler, director for the Center for Studies of Addiction at the University of Pennsylvania. “Three years is not a very long time to make a market where there really isn’t much of a market and they didn’t.” The company discontinued its effort to market the drug in 1997.

Many of the same marketing problems also persist for acamprosate.