Category Archives: Renal Pharmacology

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“The US FDA has recently published a guidance document on Pharmacokinetics in Patients with Impaired Renal Function.
Drug metabolism and excretion in the renal impaired patients-
After entering the body, a drug is eliminated either by excretion or by metabolism. Although elimination can occur via any of several routes, most drugs are cleared by elimination of unchanged drug by the kidney and/or by metabolism in the liver. For a drug eliminated primarily via renal excretory mechanisms, impaired renal function may alter its pharmacokinetics (PK) and pharmacodynamics (PD) to an extent that the dosage regimen needs to be changed from that used in patients with normal renal function. Although the most obvious type of change arising from renal impairment is a decrease in renal excretion, or possibly renal metabolism, of a drug or its metabolites, renal impairment has also been associated with other changes, such as changes in absorption, hepatic metabolism, plasma protein binding, and drug distribution. These changes may be particularly prominent in patients with severely impaired renal function and have been
observed even when the renal route is not the primary route of elimination of a drug. Thus, for most drugs that are likely to be administered to patients with renal impairment, PK characterization should be assessed in patients with renal impairment to provide rational dosing recommendations. The guidance recommends the following: When studies of PK in patients with impaired renal function should be performed—and conversely, when they may be unnecessary; The design and conduct of PK studies in patients with impaired renal function; The design and conduct of PK studies in end-stage renal disease (ESRD) patients treated with dialysis (hemodialysis or peritoneal dialysis); The analysis and reporting of the results of such studies; Representation of these results in approved product labeling. ”