In pharmacology, what is meant by 'biotransformation'?

Biotransformation refers to the chemical modifications made by an organism on a substance, particularly regarding drugs. It is primarily concerned with converting lipophilic (fat-soluble) compounds into more hydrophilic (water-soluble) forms, which facilitates their excretion from the body. This transformation usually occurs in the liver, where enzymes metabolize the drugs into metabolites that are often less active or inactive.

The importance of biotransformation lies in its role in pharmacology: it determines the duration and intensity of a drug's effect, influences drug interactions, and affects the potential for toxicity. By converting drugs into more water-soluble forms, the body can more effectively remove these substances through urine or bile, thereby maintaining homeostasis and preventing accumulation that could lead to adverse effects.