There are two basic pharmacokinetic processes on which the pharmacological response of a drug is dependent. Those are namely, drug absorption and drug disposition. On the other hand, the rate of elimination decides the duration and intensity of action of a drug. The biochemical modification of xenobiotics including drugs from one chemical form to another is termed as Metabolism. The same process specifically for drugs is known as Drug Metabolism. It results in metabolites which are highly polar, thus, easily excretable form the body. Consequences of Drug Metabolism: The consequences vary from pharmacological inactivation to toxicological activation to pharmacological activation of drugs. For example: oxyphenbutazone is an active metabolite of phenylbutazone, which possesses better analgesic activity and causes lesser gastric irritation.