Pharmacokinetics of amikacin in patients with renal insufficiency: relation of half-life and creatinine clearance.

The half-life of amikacin after a single intramuscular injection was determined in patients with severe renal failure who received 3.75 mg of drug/kg and in patients with various degrees of renal function who received 7.5 mg of drug/kg. The relation of the half-life of amikacin to levels of serum creatinine is practically identical to that of kanamycin. However, although concentrations of serum creatinine remained practically unchanged, rates of creatinine clearance may by considerably decreased in older subjects. This decrease may result in overestimation of the rate of glomerular filtration and subsequent overdosage. Therefore, the half-life of amikacin should be derived from values of rates of creatinine clearance or be predicted with use of a nomogram. The calculated half-life values may be used for development of appropriate dosage schedules for patients with various degrees of renal function. Such schedules would ensure therapeutic levels of drug and avoid potentially toxic accumulation of antibiotic.