text: Results indicate that AM4054 serves as an effective CB(1) discriminative stimulus, with an onset and time course of action comparable with that of the << CB(1) >> agonist [[ Δ(9)-tetrahydrocannabinol ]], and that the inverse agonist rimonabant and the neutral antagonist AM4113 produce dose-related rightward shifts in the AM4054 dose-effect curve, indicating that both drugs surmountably antagonize the discriminative stimulus effects of AM4054.