Individualization of treatment with gentamicin in neonates based on drug concentration in the blood serum

Aim

To evaluate how useful it is to make measurements of gentamicin concentrations in newborns' b/ood in order to optimize antibiotic therapy.

Material and methods

73 newborns empirically treated with gentamicin, in doses consistent with the Neofax^® guidelines. There were 152 measurements of maximum and minimum serum gentamicin concentrations. Samples were determined based on the chemiluminescence technique on the Siemens Advia Centaur analyzer. The concentrations of gentamicin that were measured were compared with various therapeutic ranges used in the literature.

Results

According to the standards adopted in the University Hospital in Wrocław, the maximum concentration was reached in 38.16% of all the chi/dren, white the minimum in 26.32%. In other chi/dren the concentrations were below or above the therapeutic range. According to the Neofax^® guidelines, the intended maximum concentration was observed in 71.05% of the newborns, and the minimum in 32.89%. The minimum concentration of <2 mg/L was found in 93.42% of the newborns, white >2 mg/L was determined in 33.33%, despite a 48-hour dosing interval. These were premature ba bies (<28th week of gestational age) and 55.56% of them reached a maximum concentration of 5-12 mg/L.

There was no significant correlation between maximum or minimum concentration and gestational age or body weight.

Conclusions

1. The dosage of gentamicin in newborns according to the Neofax^® recommendations does not ensure achieving the intended serum antibiotic concentrations. 2. In order to optimize gentamicin therapy in newborns it is necessary to individualize the dose based on measurements of drug concentrations in the blood and pharmacokinetic calculations.