On the opioid nature of phencyclidine and its 3-hydroxy derivative

Phencyclidine (PCP) and its 3-hydroxy derivative (PCP-3-OH) caused a dose-dependent, naloxone reversible inhibition of the response of the guinea pig ileum to electrical stimulation. Unlike PCP, PCP-3-OH exerted an opioid antagonistic effect in the mouse vas deferens bioassay. Whereas both compounds displayed a high affinity in displacing [3H]SKF-10047 binding to rat brain membranes, PCP-3-OH displayed a high affinity to [3H]morphine receptors also. The mediation of alpha- and mu-receptors in the opioid effects of these drugs is discussed.