Receptor binding and antinociceptive properties of phencyclidine opiate-like derivatives.

The relative potencies of a new series of phencyclidine (PCP) analogs for the displacement of [3H] morphine binding from rat brain homogenates are well correlated with the relative antinociceptive potencies in the test of writhing induced by acetic acid (0.6%). One group of compounds exerts a completely naloxone-reversible analgesic effect, while the effects of a second group are partially reversed by naxolone. These findings and the structural differences between the two groups suggest that their analgesic is mediated through different opiate receptors.