Phencyclidine (PCP, I) and many of its derivatives have demonstrated many pharmacological effects. They
interact with a number of neurotransmitter systems within the central nervous system. For example, Phencyclidine is a
noncompetitive antagonist of the N-methyl-d-aspartate (NMDA) subtype of the glutamate receptor, and it causes the
release and inhibits the reuptake of monoaminergic neurotransmitters, including dopamine, serotonin and norepinephrine.
In this study, new thienyl (TCP, II), as well as benzothiophen (BTCP, III) derivatives (IV-VII) were synthesized. The
acute and chronic pain activities of these drugs were studied using the tail immersion and formalin tests on mice and the
results were compared with PCP, TCP and control groups at dosage of 10 mg/kg. The results indicated that the drug VII
produced more analgesic effects on acute chemical pain in formalin test compared with other drugs. In addition, this
analgesic effect was remarkably seen for drugs II, VI and VII in chronic pain in the mentioned test in comparison with
other drugs. Also, the results showed that acute thermal pain could be diminished by drugs VI, II and I compared with
other drugs in tail immersion test. It can be concluded that more analgesic effects of new BTCP analogues (VI and VII)
may be concerned with antinociception activities of benzothiophene group and also with binding to cocaine site on the
dopamine transporter receptor which seems to be more potent than PCP receptor in decreasing pain.