Basic pharmacology relevant to drug abuse assessment: tramadol as example.

Tramadol is a centrally acting analgesic in widespread use throughout the world. Although there is extensive preclinical, clinical, post-marketing and epidemiological data indicating relatively low--but not zero--abuse/dependence, questions continue to arise about its abuse potential and appropriate regulatory classification. This article considers these questions from the point of view of the basic pharmacology of tramadol. There is nothing unique about tramadol in this regard, but its multimodal mechanism of action, pharmacologically active enantiomers, and active metabolite make it a particularly instructive and relevant example.