Presented at the Neonatal Society 2004 Spring Meeting.
McCullough S, Sinha AK, Ousetta I, Hird MF, Kempley ST
Neonatal Unit, Royal London Hospital, Whitechapel, E1 1BB
Background: Gentamicin has a narrow therapeutic window. The use of a regimen which achieves adequate therapeutic levels (peak 5 -10 mg/mL, trough <2 mg/mL) is important both to ensure efficacy with bactericidal peak levels while minimising the nephrotoxicity and ototoxicity associated with sustained high trough drug levels. There are several gentamicin dosage regimens in use, generally based on an infant’s gestation. A recent report suggests that it is preferable to use a once daily regimen at a higher dose (4mg/kg) in less immature babies (1). Concern over the adequacy of our existing practice prompted us to investigate the effects of a similar higher dose regimen across a wider gestation range than has been previously published.
Objective: To assess whether the new regimen achieved a greater number of therapeutic levels without a resultant increase in toxic levels.
Method: A retrospective casenote analysis. The first gentamicin levels recorded after initiating therapy were retrieved for all neonates during a discrete 3 month period for each regimen.
Results: The patients’ demographic details, dose regimen and resultant gentamicin levels are shown in the Table 1. Infants receiving gentamicin according to the newer regimen were of a significantly lower gestation & weight (p<0.05).
Table 1: * = p<0.05, **=p<0.01, NS=not significant
A higher percentage of infants achieved adequate peak levels (76% vs 62%) and less babies had higher toxic trough levels (12% versus 36%) on the newer regimen. There was no correlation between levels and gestation, creatinine levels or birthweight.
Conclusion: Increasing the dose and lengthening the dosing interval resulted in a higher proportion of neonates achieving satisfactory levels and a lower rate of toxic trough levels.
References
1. Thureen et al Pediatrics 1999:103 (3);594-8