PHARMACOKINETICS OF ONCE-DAILY DOSING OF GENTAMICIN IN NEONATES

In a prospective, randomized trial of once-daily versus twice-daily in travenous or intramuscular dosing with gentamicin, 11 neonates receive d 5.0 mg/kg once daily and 15 received 2.5 mg/kg twice daily for 2 or 3 days. The once-daily intravenous dosing group and the twice-daily in travenous or intramuscular dosing group, respectively, had mean steady -state gentamicin peak concentrations of 10.7 versus 6.6 mu g/ml (p < 0.05), 6-hour postdosing concentrations of 4.7 versus 2.8 mu g/ml (p < 0.05), trough concentrations of 1.7 versus 1.7 mu g/ml, elimination h alf-life of 8.8 versus 5.4 hours (p < 0.05), and volume of distributio n at steady state of 0.57 versus 0.46 L/kg. No nephrotoxic effects wer e identified in and group. Once-daily gentamicin therapy with 5.0 mg/k g in neonates achieves peak serum levels that are more suitable for op timal bacterial killing than those which traditional regimens achieve. Similar trough levels suggest that even larger doses and longer dosin g intervals may be ideal in term neonates.