Radioimmunoassay for phencyclidine.

A sensitive and specific radioimmunoassay has been developed for the drug phencyclidine (PCP). Levels as low as 50 pg (200 femto-moles) of PCP can be detected. The specificity of the antisera has been investigated by inhibiting the [3H]PCP-anti PCP reaction with the parent drug, metabolites, and other related compounds. Three urinary metabolites, 4-phenyl-4-piperidinocyclohexanol, 1-(1-phenylcyclohexyl)-4-hydroxypiperidine and 1-phenylcyclohexylamine inhibit 2,5, and 0.002% as effectively as PCP respectively. Plasma samples supplemented with PCP (1.2 to 10,000 ng/ml) can be analyzed directly by this procedure.