After a drug is absorbed and distributed in the body, which organ is primarily responsible for its metabolism?

The liver is primarily responsible for the metabolism of drugs in the body. This is due to its unique position in the body's circulatory system and its specialized cells that contain enzymes responsible for biotransformation. The metabolic processes that occur in the liver transform lipophilic compounds into more hydrophilic metabolites, making them easier for the body to excrete.

Additionally, the liver plays a crucial role in drug detoxification, ensuring that potentially harmful substances are effectively broken down or altered so they can be eliminated from the body. This process can involve various mechanisms, including oxidation, reduction, hydrolysis, and conjugation, facilitated by a range of enzymes, particularly those in the cytochrome P450 family.

Other organs, such as the kidneys and lungs, also participate in the excretion of drugs and their metabolites, but they are not primarily responsible for the metabolic processing. The intestines contribute to the absorption and some degree of metabolism of certain substances, but again, they do not take precedence over the liver in drug metabolism. Thus, the liver's central role solidifies its status as the primary organ for drug metabolism in the body.