Psychotomimetic drugs, specific

Phencyclidine (1 -[1-phenylcyclohexyl]pi peridine HC1 PCP) and its active derivatives produce unique behavioral effects in animals and psychotomimetic effects in humans. Drugs of this class have been demonstrated to bind saturably, reversibly, and with high affinity to specific binding sites in brain (Hampton et al. 1982 Quirion et al. 1981 Sircar and Zukin 1983 Vincent et al. 1979 Zukin and Zukin 1979). These sites have been shown to exhibit a characteristic heterogeneous regional distribution pattern (Quirion et al. 1981 Sircar et al., submitted for publication Zukin and Zukin 1979) distinct from that of any other receptor type. 

It has been adequately proved based on the available evidence that naloxone specifically antagonizes the opioid effects, such as respiratory depression, psychotomimetic effects, and pupillary constriction, by means of genuine competition for the receptor sites. The drug disappears from serum in man in a much rapid fashion. After an IV administration it is distributed quite rapidly in the body. It is found that the biological half-life in adults ranges between 30 to 81 minutes whereas, the mean half-life in neonates is 3.1 and 0.5 hour. 

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