Gentamicin usage in newborns — a simple and practical regime

OBJECTIVE: To audit the gentamicin usage guidelines due to concerns that it resulted in too many sub-therapeutic peak levels, devise a new guideline and re-audit after change in practise. METHOD: A prospective audit of 50 sets of gentamicin levels on the Old Gentamicin Regime was conducted. Desired levels were a trough <2 microg/ml and peak between 5-10 microg/ml.These were taken just before and one hour after the third dose respectively. Peak levels were found to be in the sub-therapeutic range in the majority on this regime. Therefore the New Gentamicin Regime was put into practise. A re-audit was conducted of the new gentamicin regime and 60 trough levels were taken. Peak levels were taken in only 20 newborns with the intention of not doing peak levels routinely if these were satisfactory and the data were analysed. RESULTS: Although trough levels were satisfactory in 98% (49/50), peak levels were sub-therapeutic in 92% (46/50) on the old gentamicin regime. Following change in practise to the new gentamicin regime trough levels were satisfactory in 96.6% (58/60). We collected 20 peak levels and these were satisfactory in 80% (16/20). CONCLUSIONS: The new gentamicin usage guideline achieves peak levels in the therapeutic range in the majority without any added risk of toxic trough levels. Peak levels need not be done routinely in all newborns on the new regime.