Concentration of Chloramphenicol in the Urine and Blood in Relation to Renal Function

Abstract

The excretion of biologically active chloramphenicol in urine diminishes linearly with decreasing renal function. When the renal function is reduced to an endogenous creatine clearance under 20 ml./min., less than 1% of the dose administered is excreted as the active compound, compared with 5-10% for normal renal function. The maximum excretion of chloramphenicol found at this degree of renal insufficiency was 10–20 μg./ml. of urine, compared with 150–200 μg./ml. for normal renal function. The low concentrations of urine might explain the poor correlation between chloramphenicol sensitivity tests in vitro and the results when treating infections of the urinary tract in patients with renal insufficiency. In elderly patients with a physiologically decreased renal filtration the urinary concentrations of chloramphenicol might be too low, increasing the risk for development of drug-resistant micro-organisms. The level of biologically active chloramphenicol in blood was only slightly influenced by the renal function, while metabolites of the drug accumulated in patients with decreased renal function. © 1966, British Medical Journal Publishing Group. All rights reserved.