Metabolism of drugs of abuse: Its contribution to the toxicity and the inter-individual differences in drug sensitivity

Abuse of drugs remains a serious and world-wide problem. As exemplified by opioids, there are large inter-individual differences in the effects and toxicity of drugs. However, the mechanism underlying such inter-individual differences remains largely unknown. Since, in many cases, drug metabolism affects the effects of drugs, the different metabolic capacity of individuals may explain these inter-individual differences. In this review, we shall focus on drugs of abuse and survey briefly their metabolism and the enzymes involved. In addition, we shall discuss the putative origin of the inter-individual differences in sensitivity to drugs of abuse.