CYP2D6 (Cytochrome P450 2D6) is a crucial liver enzyme responsible for metabolising approximately 25% of all clinically used drugs, including antidepressants, opioids, beta-blockers, and antipsychotics. Variations in CYP2D6 activity—due to genetic differences or CYP2D6 inhibitors—can significantly impact how medications are processed in the body. Real-World Example: Consider a patient prescribed codeine, a common pain reliever. […]