The importance of cytochrome P450 monooxygenase CYP2D6 in palliative medicine.

The enzymes in the cytochrome p450 monooxygenase system (CYP) are the major enzymes responsible for metabolizing medications. The CYP2D6 isomer is responsible for metabolizing certain opioids, neuroleptics, antidepressants and cardiac medications. Owing to CYP2D6's low capacity and high affinity it is easily saturated by substrate and/or inhibited, resulting in pharmacokinetic interactions. Polymorphisms of the structural gene are common, leading to wide inter-individual and ethnic differences in drug metabolism. Clinically important drug interactions, which may be anticipated in the palliative medicine population, are reviewed.