A state, produced by repeated or prolonged drug exposure, in which the presence of drug in the body is required to maintain normal physiological function. This state is recognizable only by the occurrence of a withdrawal reaction when the drug is removed, that is reversed when the drug is again administered. Such dependence is believed to result from adaptive changes in the nervous system, opposite in direction to the drug effects, which offset these effects when drug is present, and produce a "drug-opposite" effect in its absence. Physical dependence is not synonymous with addiction, and can occur in nonaddicted persons.

See Also

Tolerance and Physical Dependence)