ONCE-DAILY VERSUS TWICE-DAILY AMIKACIN REGIMEN - EFFICACY AND SAFETY IN SYSTEMIC GRAM-NEGATIVE INFECTIONS

Three hundred and sixteen patients with serious infections verified or suspected to be of Gram-negative aetiology were treated in an open, randomized, comparative multicentre study with amikacin 15 mg/kg/day given either as a single dose or in two divided doses at 12 h intervals. Two hundred patients were evaluated for efficacy and all 316 for safety. The efficacy of both dosage regimens was very good with a satisfactory clinical response in 90% of the patients. There were no significant differences between the two regimens regarding efficacy and safety. This was also confirmed in an analysis according to the principle of 'intention-to-treat' including all randomized patients. In 218 patients additional therapy, most commonly with piperacillin or ampicillin, was considered necessary. The mean peak serum concentration of amikacin was 40·9 mg/L in the once-daily group, which is 10 × MIC for most Gram-negative bacteria, compared to 244 mg/L in the twice-daily group, which is 6 × MIC. Mean trough serum concentrations after 24 h were 1·8 mg/L in the once-daily group and 3·1 mg/L after 12 h in the twice-daily group. These serum concentrations were often close to or just below the MICs of the isolated pathogens. Drug related adverse reactions were seen in 40 (13%) of the patients. Among the adverse reactions with possible or probable relation to amikacin were 20 nephrotoxic events, nine in the once-daily group and 11 in the twice-daily group. A multivariate analysis of selective causative factors and nephrotoxic events gave a low correlation for once- vs twice-daily amikacin therapy. Five ototoxic events were observed, three in the once-daily group and two in the twice-daily group. One patient in the once-daily group experienced nausea in connection with amikacin infusions. © 1993 The British Society for Antimicrobial Chemotherapy.