Intravenous administration of gentamicin once daily versus thrice daily in adults

The efficacy and safety of intravenous gentamicin administered once daily versus thrice daily was evaluated in adults. Patients over 16 years of age with a suspected or documented gram-negative infection were randomly divided into two groups: one group received gentamicin intravenously 4.5 mg/kg once daily (n = 48), and the other received 1.5 mg/kg every eight hours (n = 52). Baseline characteristics were comparable in the two groups. The mean peak level of gentamicin in the once daily group was significantly higher than that in the thrice daily group, 8.7 +/- 2.3 mg/l versus 4.6 +/- 1.2 mg/l (p < 0.005), and the trough level lower, 0.7 +/- 0.3 mg/l versus 1.1 +/- 0.9 mg/l (p < 0.005). The clinical cure rate was significantly higher in the once daily group, 42 of 48 (87.5%) versus 36 of 52 (69.2%). The microbiological cure rate was also better in the once daily group than in the thrice daily group (31 of 36 versus 28 of 38 patients evaluated), although this difference was insignificant. Nephrotoxicity was not observed in either group, but ototoxicity was present in three of the patients treated thrice daily. A once daily dosing regimen of gentamicin is more effective and less ototoxic than a thrice daily regimen.