Analysis of phenazepam and 3-hydroxyphenazepam in post-mortem fluids and tissues

Phenazepam is a benzodiazepine that is predominantly used clinically in the former Soviet
states but throughout the wider world is being abused. This study reports the tissue
distribution and concentration of both phenazepam and 3-hydroxyphenazepam in 29 cases
quantitated by LC-MS/MS in a variety of postmortem fluids (subclavian blood, femoral
blood, cardiac blood, urine, vitreous humor) and tissues (thalamus, liver and psoas
muscle). In 27 cases the cause of death was not directly related to phenazepam (preserved
(fluoride/oxalate) femoral blood phenazepam concentrations 0.007 mg/L to 0.360 mg/L
(median 0.097 mg/L)). In two cases phenazepam was either a contributing factor to, or the
certified cause of death (preserved (fluoride/oxalate) femoral blood 0.97 mg/L and 1.64
mg/L). The analysis of phenazepam and 3-hydroxyphenazepam in this study suggests that
they are unlikely to be subject to large postmortem redistribution and that there is no direct
correlation between tissues/fluid and femoral blood concentrations. Preliminary
investigations of phenazepam stability comparing femoral blood phenazepam
concentrations in paired preserved (2.5% fluoride/oxalate) and unpreserved blood show
that unpreserved samples show on average a 14% lower concentration of phenazepam
and we recommend that phenazepam quantitation is carried out using preserved samples
wherever possible.