Evolution of a neonatal gentamicin dosing protocol in a small community hospital.

The effects of conventional dosage of gentamicin of 2.5 mg/kg given every 12 hours was retrospectively investigated in a small community hospital. Consistent with previous results in large hospitals, the conventional dosage of gentamicin commonly resulted in serum concentrations associated with toxicosis. Results were compared with those obtained prospectively according to a gentamicin dosing protocol that used a formula based on gestational age. The gestational age regimen provided similar peak and significantly lower trough serum concentrations; statistical analysis indicated no demographic differences in the compared groups. Very few neonates who received gentamicin according the gestational age formula were exposed to gentamicin serum concentrations associated with an increased risk of toxicosis. An absence of any significant differences in mean peak and trough serum concentrations in subgroups of neonates treated according to the gestational age formula suggested that use of the gentamicin dosing protocol was appropriate for all neonates. The dose of 3.5 mg/kg used in the gestational age formula was predicted to have resulted in initial gentamicin peak serum concentrations > 5 micrograms/ml in nearly 90% of neonates. The experience obtained with the gestational age formula allowed revision of the gentamicin dosing protocol to provide for more cost-responsible serum concentration monitoring.