"Comparably massive" penicillin G therapy in renal failure.

Impairment of penicillin G excretion in renal failure may result in life-threatening, dose-related toxicity. We report a method for achieving a desired mean serum penicillin G concentration in patients with renal failure, with minimal risk of both undertreatment and drug toxicity. The method is based on the linear relation between the total plasma clearance of penicillin G (Cpen) and the endogenous creatinine clearance. The daily maintenance dose of penicillin G (units) is defined by the product, Cpen (ml/min) times desired mean serum penicillin G concentration (mug/ml) times 2300. Application of this method to patients with various degrees of renal impairment by either constant-rate infusion or intermittent infusion gave serum penicillin G concentrations within the desired range in all but 1 of 15 instances. On the basis of these observations, practical guidelines for "comparably massive" penicillin G therapy are suggested.