Pharmacological differences between once daily and twice daily gentamicin dosage in newborns with suspected sepsis

To evaluate two different regimens for gentamicin administration (once or twice daily) in newborns with suspected sepsis, and the ability of these regimens to achieve recommended serum gentamicin concentrations (SGC) within the therapeutic range. Setting Neonatal intensive care unit.

We conducted a retrospective study of newborns > or =34 weeks gestational age (GA) admitted with suspected sepsis to the neonatal unit at Stavanger University Hospital from 1st February 2003 to 31st May 2005. During the first period patients received gentamicin 2.5 mg/kg twice daily (n = 62) and during the last period patients received gentamicin 4 mg/kg once daily (n = 73). In both groups, levels of gentamicin were obtained before and after the third given dose.

Mean peak levels were lower and mean trough levels were higher in the twice daily regimen compared to the once daily regimen (P < 0.001 for both). About 16 newborns in the twice daily regimen had trough levels higher than the recommended level (<2 microg/ml) compared to two children in the once daily regimen (P < 0.001). High peak levels (>10 microg/ml) were achieved in one child in the twice daily regimen compared to eight children in the once daily regimen (P = 0.04). The number of children with a low peak level (<5 microg/ml) was only three and one respectively (n.s).

In newborns with suspected sepsis, gentamicin 4 mg/kg once daily provided higher peak and lower trough gentamicin levels compared to administering gentamicin 2.5 mg twice daily.