Gentamicin Dosages for Renal Insufficiency

The percent hourly loss and serum half-life (T½) of gentamicin were determined after an intramuscular dose of from 0.8 to 1.5 mg/kg body weight in each of 18 patients with various degrees of impaired renal function and in 6 patients with normal renal function. There was a linear relationship between the loss of gentamicin and the endogenous creatinine clearance (CCr). The percent hourly loss could be estimated by dividing the value of the CCr (ml/min/1.73 m2 body surface area) by four. There was a curvilinear relationship between the serum creatinine concentration and the T½ of gentamicin. The nature of the curve was such that for clinical purposes the T½ of gentamicin could be estimated by multiplying the value of the serum creatinine (mg/100 ml) by four. These data provide a possible basis for individualized adjustment of dosage of gentamicin for patients with impaired renal function.