Carisoprodol: update on abuse potential and legal status.

Carisoprodol is a centrally acting skeletal muscle relaxant of which meprobamate, a controlled substance, is the primary active metabolite. The abuse of carisoprodol has increased dramatically in the last several years. A withdrawal syndrome occurs in some patients who abruptly cease carisoprodol intake. The symptoms of this syndrome are similar to those seen with meprobamate withdrawal, suggesting that they may result from withdrawal from meprobamate accumulated with intake of excessive carisoprodol; however, carisoprodol is capable of modulating GABAA function, which may contribute to its abuse potential.There has been considerable debate about whether carisoprodol should be considered a controlled substance. Carisoprodol was removed from the market in Norway on May 1, 2008, but may still be used by specially approved patients. Carisoprodol was classified as a controlled substance in several US states, and effective January 11, 2012, became a schedule IV controlled substance at the US federal level. This article updates the literature on abuse potential and examines recent developments regarding the legal status of carisoprodol.