Phenazepam abuse in the UK: an emerging problem causing serious adverse health problems, including death.

Objective: Phenazepam (fenazepam; 7-bromo-5-(2-chlorophenyl)-1,3-dihydro-2H-1,4-benzodiazepin-2-one; PNZ, 'Bonsai') is a benzodiazepine developed in the former Soviet Union during the 1970s to treat neurological disorders, epilepsy, and alcohol withdrawal syndrome. Its recreational use appears to have increased over recent years. Because of the lack of accessible data on this substance, it is important that information is made available to health professionals.