Which drug is primarily metabolized by the CYP2D6 enzyme?

Codeine is primarily metabolized by the CYP2D6 enzyme, a member of the cytochrome P450 family of enzymes that play a significant role in drug metabolism. When codeine is administered, CYP2D6 converts it into its active metabolite, morphine, which is responsible for much of its analgesic effects. The efficiency of this metabolic pathway can vary greatly among individuals due to genetic polymorphisms in the CYP2D6 gene, leading to different responses to codeine therapy.

Understanding the metabolism of codeine through CYP2D6 is crucial in clinical settings, as it helps guide appropriate dosing and potential efficacy, especially in individuals with varying CYP2D6 enzyme activity, such as poor or ultra-rapid metabolizers.

Other drugs listed, such as ibuprofen, aspirin, and paracetamol, are mainly metabolized through pathways that do not involve CYP2D6, relying instead on different hepatic enzymes for their metabolism and elimination from the body.