[Pharmacokinetic changes in renal failure].

DRUG PHARMACOKINETICS: One of the first steps in the clinical development of drugs consists in studies of their pharmacokinetics. Dosage and administration interval necessary to ensure secure and efficient plasma levels are derived from the values of pharmacokinetic parameters. Renal disease usually implies multiple pathophysiological modifications that generate alteration in drugs pharmacokinetic profile. Those modifications mainly occur on elimination phase but also to a significant extent on absorption and distribution. PATHOPHYSIOLOGICAL CHANGES: In this article we describe potential alteration in drugs absorption, distribution (volume of distribution, binding to plasma proteins), hepatic or renal metabolism, and parent compound and/or metabolites elimination in patients with renal insufficiency. Furthermore, in patients with end-stage renal disease treated by dialysis, drugs are likely to be removed by extracorporal epuration and dosage and/or interval modifications should thus be applied to treatments in those patients. CLINICAL ASSESSMENT: Pharmacokinetics of drugs should be evaluated in patients with renal failure to determine whereas dosage and/or administration interval should thus be modified to enhance tolerance and pharmacological efficacy. Such studies are obviously necessary for drugs that are mainly excreted unchanged in urine. They should also be performed for drugs that are mainly degraded in the liver with emphasis on metabolites pharmacokinetics.