Comparative evaluation of six extended-interval gentamicin dosing regimens in premature and full-term neonates

Purpose. Six extended-interval gentamicin dosing regimens were comparatively evaluated in premature and full-term neonates. Methods. Data regarding six physician-ordered dosing regimens of gentamicin for neonates in a hospital neonatal intensive care unit were collected and analyzed. Neonates of gestational age (GA) 29 weeks or younger received 4.5 mg/kg every 48 hours. Neonates of GA 30-34 weeks received one of three dosing regimens: 3.5, 4, or 4.5 mg/kg every 36 hours. Neonates of GA 35 weeks or older received either 3.5 or 4 mg/kg every 24 hours. Blood samples were collected 30 minutes before and 30 minutes after the third dose was infused for binary trough and peak level determinations, respectively. Results. Peak gentamicin concentrations in the target range were attained most often in neonates of GA 29 weeks or younger who received gentamicin 4.5 mg/kg every 48 hours, in neonates of GA 30-34 weeks treated with gentamicin 3.5 mg/kg every 36 hours, and in neonates of GA 35 weeks or older treated with gentamicin 3.5 mg/kg every 24 hours. Conclusion. For neonates of GA 30-34 weeks, gentamicin 3.5 mg/kg every 36 hours resulted in the highest percentage of peaks in the target range compared with 4 and 4.5 mg/kg every 36 hours. For neonates of GA 35 weeks or older, gentamicin 3.5 mg/kg every 24 hours provided the highest percentage of peaks in the target range compared with 4 mg/kg every 24 hours. The differences between the percentages of trough values in the target range of 0.5-2 mu g/mL were not significant among dosing subgroups within each age group.