Performance of a dosage individualization table for extended interval gentamicin in neonates beyond the first week of life.

OBJECTIVE

To assess the performance of a gentamicin dosing table for the individualization of extended-interval dosing (EID) in a neonatal population >7 days old.

METHODS

A prospective observational study was carried out on gentamicin concentrations achieved using a dosing table in neonates >7 days old. Neonates were given 5 mg/kg IV gentamicin; then a table using 22 h post-first dose gentamicin concentrations was used to individualize dosing intervals. Pre- and post-serum gentamicin concentrations were measured and used to calculate the true peak and trough concentrations achieved.

RESULTS

Use of the table resulted in dosing intervals that provided appropriate peak (mean 9.8 ± 1.8 mg/L) and trough (mean 0.6 ± 0.3 mg/L) concentrations in all neonates (n = 38). All trough concentrations were <2 mg/L, 83% were <1 mg/L. The majority of peak concentrations were in the usual target range (87%, 5-12 mg/L), with a few being in a higher, although likely safe range (13%, 12.1-15.7 mg/L).

CONCLUSIONS

Use of this dosing table to individualize extended-interval gentamicin dosages in neonates >7 days old resulted in appropriate peak and trough concentrations in all neonates studied. This allows appropriate extended-interval aminoglycoside dosages in neonates early in treatment.