Pharmacokinetics of amikacin for treatment of urinary tract infections in patients with reduced renal function.

Amikacin (250 mg four times daily for 10 days) was administered intramuscularly to 22 patients with long-standing, severe infections of the urinary tract, in each case superimposed on chronic uropathy or nephropathy. Therapy with amikacin was completely successful in 14 patients (sterile 14-day follow-up urine specimens obtained by suprapubic needle aspiration of the bladder) and partially successful in three (sterile three-day but positive 14-day follow-up urine specimens). Five patients were judged to be treatment failures. Quantitative assessment of pyuria revealed a significant drop in the rate of excretion of white cells to near normal levels not only in patients who were cured but also in others, a finding which suggests that the infectious process had been affected by amikacin in all cases. The course of the disease in individual patients suggested that amikacin therapy can be successful after a long series of failures from treatment of such conditions with other antibiotics. Additional pharmacokinetic studies indicated that the half-life of amikacin may be increased five- to 10-fold in patients with renal insufficiency. A tentative dosage schedule was prepared for patients with various degrees of impaired renal function on the basis of average half-life values.