Amphetamine is understood to inhibit monoamine oxidase, whereas the flexibility of amphetamine and its metabolites to inhibit various P450 isozymes as well as other enzymes has not been adequately elucidated. In vitro experiments with human microsomes indicate minor inhibition of CYP2D6 by amphetamine and small inhibition of CYP1A2, 2D6, and 3A4 by