drug oxidation

Drug oxidation is the most common way the body chemically tweaks a drug. In everyday terms, it is the controlled equivalent of letting something react with oxygen — but instead of rusting metal, the cell precisely inserts an oxygen atom or strips away electrons to make the drug a bit more water-friendly.

Oxidation is the predominant phase I reaction and is carried out mainly by cytochrome P450 enzymes, which use molecular oxygen and the cofactor NADPH. Typical transformations include hydroxylation, N- and O-dealkylation, deamination, and sulfoxidation — all introducing or unmasking a polar, often reactive functional group.

Oxidation usually nudges a drug toward elimination, but the consequences vary. It can inactivate a drug, convert a prodrug into its active form, or generate a chemically reactive metabolite capable of damaging cells. Because oxidation hinges on enzyme amount and activity, it is highly sensitive to enzyme induction, inhibition, and genetic variation.