Asymmetric substitution between methamphetamine and amphetamine: Study of drug discrimination

Abstract

Methamphetamine (METH) is a form of amphetamine (AMPH) that is structurally and functionally similar. However METH differs from AMPH in that, at comparable doses, much higher levels of METH get into the brain, making it a more potent psychostimulant than AMPH. Despite of this, it has been reported that both METH and AMPH produce similar behavioral effects. Drug discrimination procedures are behavioral tools used to assess if two drugs produce similar or different behavioral effects. In the present study we evaluated the ability of various doses of AMPH to substitute for equivalent doses of METH in rats trained to discriminate METH from saline using a conditioned taste aversion as the drug discriminating procedure. After rats learned the discrimination METH-saline, various doses of METH or AMPH were evaluated on substitution tests. The results showed that different doses of METH produced a dose-dependent substitution. However, different doses of AMPH produced a partial dose-dependent substitution using equivalent doses of METH. These results suggest that METH produces higher behavioral effects than AMPH on a drug discrimination procedure.