Tofisopam (marketed under brand names Emandaxin and Grandaxin) is a 2,3-benzodiazepine derivative that is marketed in several European countries as the anxiolytic drug. Tofisopam does not bind to the benzodiazepine binding site of the gamma-aminobutyric acid receptor. One study has shown that tofisopam acts as an isoenzyme-selective inhibitor of phosphodiesterases (PDEs) with the highest affinity to PDE-4A1 followed by PDE-10A1, PDE-3, and PDE-2A3. Like other benzodiazepines, tofisopam possesses anxiolytic properties but unlike other benzodiazepines, it does not have anticonvulsant, sedative, skeletal muscle relaxant, motor skill-impairing or amnestic properties. While it may not be an anticonvulsant in and of itself, it has been shown to enhance the anticonvulsant action of classical 1,4-benzodiazepines such as diazepam (but not sodium valproate, carbamazepine, phenobarbital, or phenytoin). Tofisopam is not approved for sale in the United States or Canada. However, Vela Pharmaceuticals of New Jersey is developing the D-enantiomer (dextofisopam) as a treatment for irritable bowel syndrome, with moderate efficacy demonstrated in clinical trials so far.