Safety and tolerability of multiple doses of imipenem/cilastatin

The safety and tolerability of 1 gm imipenem and cilastatin given together every 6 hours for 10 days was evaluated in a randomized, double-blind, placebo-controlled trial in normal subjects. Nausea was more common in the drug-treated group (five of six subjects) than in the control group (two of six subjects). No consistent changes in hepatic function indices were noted. Although beta 2-microglobulin excretion showed a significant trend of rising over time in the drug group, there were no differences between groups with regard to 24-hour urinary excretion of either N-acetyl-beta-glucosaminidase or beta 2-microglobulin. Urinalysis did not reveal any casts and serial creatinine clearance determinations showed no change in renal function in either the drug- or placebo-treated groups. Pure tone audiograms were performed before and after dosing in 11 of 12 subjects; no changes were noted. We conclude that the combination of imipenem and cilastatin was well tolerated and safe.