Phenazepam is a very potent and long-acting benzodiazepine.  In Russia and several ex-Soviet states, phenazepam is available on prescription.  Clinically, it is used in the treatment of neurological disorders such as epilepsy, insomnia and during acute alcohol withdrawal.

It is mainly manufactured in tablet form but may also be supplied as a fine white powder or as a liquid supplied in dropper bottles.

More recently, increased recreational use of phenazepam has been seen in the UK, the United States and several other European countries. 

Taking phenazepam orally remains the most common route of administration; however there have also been reports of people injecting, snorting and taking it rectally.

When considering all benzodiazepines, phenazepam is most similar to clonazepam and bromazepam in terms of chemical structure, action and dosing.

A standard dose of phanazepam is 0.5mg 2-3 times a day while a significant human dose 1-2mg.  It is recommended that maximum daily doses should not exceed 10mg.  Peak effects are typically reached 2-4 hours after dosing, while the time taken for the amount in the body to decrease by 50% (the ‘half-life’) is around 60 hours.

The side effects of phenazepam resemble those seen with other benzodiazepines and are long in duration.  Associated drowsiness is of particular concern as it can potentially lead to coma with dangerously slow heart rates.