Phencyclidine and cannabinoids in vitreous humor.

Vitreous humor (VH) is routinely collected at autopsy for the testing of electrolytes and ethanol. In recent years drugs of abuse have been detected in this specimen. In this study the authors assayed 30 VH samples for phencyclidine (PCP) and 50 specimens for cannabinoids. Specimens were screened by immunoassay and then assayed for PCP by GC-FID and cannabinoids by GC/MS. Eighteen (60%) specimens screened positive for PCP using a cutoff of 25 ng/mL. Quantitative analysis showed PCP concentrations in VH that screened positive ranged 30-290 ng/mL. Corresponding blood concentrations were 50-600 ng/mL. VH PCP concentrations in the 12 cases which screened negative were 40-470 ng/mL. False negative results were probably due to matrix effects. All VH specimens screened for cannabinoids were negative. Ten negative screening specimens assayed by GC/MS yielded 1 11-nor-9-carboxy-delta-9-tetrahydrocannabinol positive result at 2 ng/mL. These data indicated that VH maybe a useful specimen for the detection of PCP but not for cannabinoids.