Renal: Introduction

Last updated: Sunday, July 12, 2015

 You can download a PDF of the text of this tutorial (it doesn't include the Learning Exercises).

Prescribing in renal failure is not an exact science. The practical knowledge of clinical professionals combined with some published evidence, and the basic principles of drug clearance provide the backbone of information available.

Drugs eliminated by the kidney
Most systemically administered drugs are eliminated at least partly by the kidney, even if it is only a tiny proportion of the administered dose. However, for some drugs, the kidney is the major site for elimination of unchanged drug and these are particularly liable to require careful dose adjustment in renal dysfunction to prevent accumulation. Examples of drugs principally eliminated unchanged by the kidney include:

AciclovirCefotaximeCiprofloxacinDigoxin
ElectrolytesFluconazoleGentamicinLithium
MeropenemMethotrexatePamidronateVancomycin

In addition, there are drugs with therapeutic activity at least partly dependent upon metabolites that are excreted unchanged by the kidney. An example is allopurinol, which has an active metabolite called oxipurinol which works in the same way as the parent drug. Some drugs have toxic metabolites that are eliminated renally. For example nor-pethidine, a major metabolite of pethidine, can accumulate in renal failure to cause CNS toxicity such as convulsions.