Phenazepam: The drug that came in from the cold

Phenazepam [7-bromo-5-(2-chlorophenyl)-1, 3-dihydro-2H-1,4-benzodiazepine-2-one], sometimes called fenazepam (Fig. 1A), is part of the 1,4-benzodiazepine group of benzodiazepines along with drugs such as diazepam, nordazepam, oxazepam and temazepam. It is however one of very few of the 1,4-benzodiazepine group to contain a bromine atom, along with the active form of gidazepam, another soviet-developed benzodiazepine5 and bromazepam. As with other benzodiazepines, it is used clinically for its anxiolytic, anticonvulsant, muscle-relaxing and sedating properties,6 and is available as 0.5-mg and 1-mg tablets,6 injectable solutions (0.1%, 0.3%) or transdermal patches (Phenopercuten).7 Clinically the dose of phenazepam that is given depends on what condition is being treated but does not exceed 10 mg day−1, and is usually not more than 5 mg day−1. Illicitly, phenazepam has been reported being sold as a powder, tablets, in the USA, spiked in lysergic acid diethylamide (LSD) mimic blotters8 and 9 and in New Zealand phenazepam has been found in a synthetic cannabinoid mix called ‘Kronic’.10 Reported recreational doses of phenazepam are around 2–10 mg, but sometimes more.8