A prospective, randomized study of amikacin and gentamicin in serious infections with focus on efficacy, toxicity and duration of serum levels above the MIC.

A multicentre prospective randomized study of amikacin and gentamicin in 135 patients with serious infections is presented. Most patients were additionally given a penicillin derivative according to Swedish therapeutic traditions. Synergism was noted in the majority of the tested strains. Clinical cure was recorded in 80% and 76% respectively of the amikacin and gentamicin patient groups. Nephrotoxic reactions were statistically (P less than 0.05) more common in gentamicin-treated patients (20%) than in the amikacin-treated ones (6%) while the corresponding figures for ototoxicity were 16% and 8% respectively (not statistically significant). Pharmacokinetic studies of the drugs showed that with the dose regimens used serum levels of amikacin above 10 times the MIC for the isolated micro-organism were registered during 75% of the 12-hour therapy interval and during 40% of the 8-hour therapy interval for gentamicin. This difference is statistically significant (P less than 0.01). We suggest that the pharmacokinetic advantages of amikacin in comparison to gentamicin might be of practical importance in the prediction of serum levels thereby lowering the risk of toxic reactions.