Synthesis and determination of acute and chronic pain activities of 1-[1-(4-methylphenyl) (cyclohexyl)] morpholine as a new phencyclidine derivative in rats.

Phencyclidine (1-(1-phenylcyclohexyl)piperidine, CAS 77-10-1, PCP, I) and many of its analogues have been synthesized and their pharmacological properties studied. In this research, new methyl morpholine derivative of phencyclidine (1-[1-(4-methylphenyl) (cyclohexyl)]morpholine, Methyl-PCM, III) was synthesized and the acute and chronic pain activities were studied using tail immersion and formalin tests on rats and compared to PCP and PCM (1-(1-phenylcyclohexyl)morpholine, CAS 2201-40-3, PCP-morpholine, II). The results Indicated that Methyl-PCM (III, 6 mg/kg, i.p) produces more analgesic effects in tail immersion test (as a model of acute thermal pain) in comparison with the PCP, PCM and control groups. Meanwhile, this analgesic effect was markedly shown 5-15 min after the compound III application. In formalin test analysis, the acute pain (phase I) could not be affected by any drugs, but the chronic formalin pain (phase II) could be diminished by PCM and especially compound III. The chronic analgesic effect of Methyl-PCM was markedly shown in the late phase of chronic pain.