Stimulus properties of ring-methyl amphetamine analogs

Abstract

There are three possible ring-substituted methyl amphetamines (or tolylaminopropanes; TAPs): oTAP, mTAP and pTAP. These agents are positional isomers of methamphetamine. Although all three isomers have been previously reported to possess amphetamine-like character, few studies have examined all three agents in comparison with (+)amphetamine. Using rats trained to discriminate 1 mg/kg of (+)amphetamine from saline under a variable-interval 15-sec schedule of reinforcement, tests of stimulus generalization were conducted with the three positional isomers. Only oTAP (ED50 dose = 4.1 mg/kg) completely substituted for (+)amphetamine. mTAP and pTAP resulted only in partial (ca. 50% amphetamine-appropriate responding) generalization. It is concluded that oTAP is capable of producing amphetamine-like stimulus effects and that it is approximately one-tenth as potent as (+)amphetamine; however, because the partial generalization produced by mTAP and pTAP was followed by disruption of behavior at slightly higher doses, it cannot be reliably stated that these latter two isomers lack amphetamine-like character.