Intrinsic activity and discriminative effects of drugs

A conceptual framework has been proposed which coherently specifies the transduction mechanisms of opiate drug stimuli at the behavioral, pharmacological, and molecular levels. One assertion that is inherent in a one-receptor theory of opiate drug discrimination is that the different magnitudes of intrinsic activity that can be produced at the receptor are associated with discrimination effects that differ qualitatively. A number of theoretical inferences are made here concerning the apparent training drug-like agonist and training-drug antagonist effects of compounds that differ in the maximal intrinsic activity which they produce at the receptor. The predicted patterns of mixed and partial agonist and antagonist effects are consistent with available data on the effects of prototype opiate compounds.