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 μg/mL were not significant among dosing subgroups within each age group.