Final answer:
The assertion that CYP3A4 and CYP2D6 are responsible for the metabolism of a large percentage of drugs is true, as these enzymes majorly contribute to drug metabolism. Their activity varies due to genetic differences, which can affect drug efficacy and safety.
Step-by-step explanation:
The statement that CYPS 3A4 and CYP2D6 metabolize a large percentage of drugs is true. Cytochrome P450 enzymes, including CYP2D6 and CYP3A4, play a significant role in the metabolism of drugs. These enzymes are responsible for the oxidative metabolism of numerous pharmaceuticals, and CYP2D6 in particular is known to metabolize around 25% of all drugs in clinical use. Variability in the activity of these enzymes due to genetic polymorphisms can lead to differences in drug efficacy and safety among individuals. Knowledge of the metabolic pathways, including the role of these CYP enzymes, is important in drug development to avoid variability in drug response and ensure efficacy and safety.
For instance, the identification of the CYP isoforms involved in the metabolism of new compounds at early in vitro stages is crucial. It is especially important to know whether highly polymorphic enzymes, such as CYP2D6, contribute to the metabolic clearance of a drug candidate. This information can influence decisions on compound modifications, predict drug-drug interaction (DDI) potential, and guide clinical development strategies.