**6. Conclusion**

Drug metabolism is very significant in controlling the pharmacokinetics. Drug metabolising enzymes carry out the metabolism of endogenous as well as exogenous substances. Phase I metabolic reactions introduce a hydrophilic group in the drug molecules where phase II metabolic reactions can take place. In this chapter, we discussed the drug metabolic reactions and enzymes involved in these reactions. Most of the drugs are metabolised by CYP450 enzymes. The study of drug metabolism is essential for the safety and efficacy of drug molecules. The pharmacokinetic properties of drugs can be predicted by carrying out drug metabolism studies. The metabolic pathways of new drugs should be determined to predict the possibility of adverse drug reactions and drug-drug interactions.
