The discriminative stimulus properties of barbiturate stereoisomers.
Pigeons were trained to discriminate an IM injection of racemic pentobarbital sodium (5.0 mg/kg) from saline under a second-order color-tracking schedule of mixed grain presentation. In a time-course study, maximal pentobarbital-appropriate responding occurred 15 min after administration of 5.0 mg/kg racemic pentobarbital sodium, the pretreatment time used for subsequent experiments. Racemic pentobarbital sodium, the R(+) and S(-) isomers of pentobarbital, racemic secobarbital sodium, and the R(+) and S(-) isomers of secobarbital all produced dose-dependent increases in pentobarbital-appropriate responding. Racemic secobarbital sodium, the secobarbital isomers, and the R(+) isomer of pentobarbital were equipotent to each other and slightly less potent than racemic pentobarbital and the S(-)-pentobarbital isomer in this regard. Except for R(+)-pentobarbital, all barbiturates caused dose-dependent decreases in response rate over the dose range tested.
D000818:Animals; D010856:Columbidae; D004193:Discrimination Learning / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D008297:Male; D010424:Pentobarbital / Q000494:pharmacology*; D019998:Racemases and Epimerases; D012631:Secobarbital / Q000494:pharmacology*; D013237:Stereoisomerism
D012631:Secobarbital; D019998:Racemases and Epimerases; D010424:Pentobarbital