Mephenesin: abuse and dependence

Mephenesin is a muscle relaxant with poorly documented clinical value. Its sedative properties have been known since its introduction on the French market. Cases of abuse and dependence have been reported, particularly since the early 2010s. Some adults were reported to be taking up to 12 g of mephenesin per day, the equivalent of an entire box. Most of them had a history of dependence on various other psychotropic drugs. Withdrawal symptoms, including tremor, anxiety, and aggression, have been reported in 3 patients. A woman who was taking no other drugs died of bronchial aspiration following mephenesin overdose. Painful muscle spasm is sometimes relieved by a short rest period, or paracetamol. Repeated requests for mephenesin should alert health professionals to the possibility of abuse. It is best to avoid mephenesin altogether, especially when the patient has a history of abuse or dependence.