Abstract

In kidney failure drugs excreted by the kidney must be administered in reduced dosage. It is first necessary to ascertain whether the drug to be prescribed is excreted by the kidney and if so, to what extent. A drug that is largely excreted by the kidney will probably accumulate if the glomerular filtration rate (GFR) is 20ml/min. or less, or the serum creatinine concentration is 3 mg per 100 ml or higher. The blood urea is a much less useful guide since it is greatly affected by the protein intake. The initial dose of any drug should be its full therapeutic dose. Subsequent doses should be reduced or more widely spaced or both. Ideally, the drug dosage should be adjusted after repeated measurements of the drug concentration in serum or plasma; repeated measurement of a drug effect can be used for the same purpose.