Pharmacokinetics in patients with renal failure.

Uremic patients manifest delayed elimination of many drugs prolonging the biological half-life, and impaired excretion of the metabolites of biotransformed drugs, some of which are toxic or biologically active. More subtle changes in bioavailability, distribution, metabolism and pharmacodynamics frequently occur, as well, rendering drug dosing hazardous, especially when the margin of safety is narrow. A review of the pharmacologic abnormalities of individual drugs exemplifies those that provide metabolic loads, those which can be eliminated by dialysis and those that can be used with the least risk. Restricting drugs use in uremic patients to unequivocal indications, limiting doses according to guidelines, restricting the duration of treatment, monitoring plasma drug levels, clinical observations and vigilant suspicion of toxicity would eliminate most toxicologic problems. Physicians must not, however, rely blindly on normograms and cookbook guidelines for dosing potentially toxic drugs.