ABSTRACT
The drugs that produce dependence are classified as Morphine-type, Barbiturate-alcohol type, Amphetamine-type, Hallucinogen-type, Cocaine-type and Cannabis-type. These drug categories reflect the differences in behavioral changes, and pharmacological responses produced by the drugs, as well as the physicochemical properties of the common structure of the drugs in each category. For most classes of drugs which induce dependence, alteration in the rate of drug metabolism in the liver may be considered of minimal importance in mechanisms for the development of dependence and tolerance. The role played in the development of tolerance to barbiturates by an increased rate of drug metabolism has been examined in experimental animals by H. Remmer. The induction of an enzyme involved in neurotransmitter synthesis by a derepression of the nucleic acid template has been suggested as the mode of biochemical adaptation to chronic stimulation by continuing drug administration.
