What is the process called when the chemical structure of a drug is altered in the body?

The process in which the chemical structure of a drug is altered in the body is known as metabolism. This is a crucial phase of pharmacokinetics that involves biochemical modifications made by an organism on a chemical compound. The body typically converts the original drug into metabolites, which may be more water-soluble for easier elimination, or may change the drug's activity level either to an active metabolite or an inactive form.

Metabolism usually takes place primarily in the liver through enzymatic processes, and it can play a significant role in determining the duration and intensity of a drug's therapeutic effects as well as its toxicity. Understanding metabolism is essential for predicting how long a drug will remain active in the system and how it will interact with other substances.

Absorption refers to the process of the drug entering the bloodstream from the site of administration, distribution involves the dispersion of the drug throughout the fluids and tissues of the body, and elimination pertains to the removal of drugs from the body, typically through urine or feces. While all these processes are essential aspects of pharmacokinetics, metabolism specifically relates to the biochemical transformation of the drug's chemical structure.