Critical drug interactions: A guide to important examples

It is critical that the physician have access to information delineating present pharmacotherapeutic knowledge when evaluating a patient for possible drug-drug interactions. Pharmacokinetic, or metabolic, drug interactions include those that alter the disposition and effects of drugs having a narrow therapeutic index and the hepatic oxidation or renal clearance of low- therapeutic-index drugs. Genetically based interactions may involve drugs that are metabolized by the hepatic cytochrome P-450 enzyme, now called CYPIID6. Pharmacodynamic drug interactions are much less studied and resist classification, although the authors enumerate some important mechanisms.