Concept of Drug Metabolism and Pharmacokinetics with Special Focus on Herbal-Drug Interaction

Abstract

T he study of how xenobiotics undergo the process of absorption, distribution, metabolism, and excretion (ADME) is conceptualized as pharmacokinetics. An understanding therefore of the PK properties is crucial and plays an important contribution in the drug discovery and development of new chemical entities. Drug metabolism is linked to the metabolic breakdown of drugs (xenobiotic metabolism) by enzyme or living organisms. The pathway involved in this process can lead to the bio-transformations that occurs in most living organisms. The drug metabolic action facilitates the detoxification process except in special circumstances where the metabolites (break down products) can lead to toxic effects. Under such circumstances the study of drug metabolism is termed as pharmacokinetics, which constitutes an important discipline as a branch of pharmacology. Herbal natural products have been used to prevent and treat diseases worldwide since the creation of mankind. However, the efficacy, safety and quality of herbal bioactive metabolites depends on the multiple components absorbed in the body and their pharmacokinetics. This review attempts to give an insight into the concept of drug metabolism and pharmacokinetics with special consideration on PK drug-herbal interactions, mechanisms, metabolizing enzymes involved and transporters implicated in the determination of the PK of xenobiotics.