Objectives.

To compare performance and cost analysis of two gentamicin regimens in infants ≥34 weeks' gestation requiring antibiotics for a 72-hour rule-out sepsis evaluation. A once-daily dosing (ODD) regimen of 4 mg/kg was compared with a standard twice-daily dosing (TDD) regimen of 2.5 mg/kg every 12 hours.

Setting and Design.

Infants at two university-affiliated Level III nurseries were prospectively temporally allocated to receive ODD (n = 27) or TDD (n = 28) as part of their 72-hour empirical antibiotic regimen. Performance of dosing regimens was based on target serum gentamicin concentrations (SGC) established prospectively as a peak of 5 to 10 μg/mL and a trough of ≤2 μg/mL. SGC were determined by fluorescence polarization immunoassay on day 3 of therapy. Cost data were obtained by distributing a questionnaire to 15 pediatric pharmacy practice sites. Inquiries were made regarding hospital cost of drug acquisition, drug supplies, drug preparation and administration, and serum concentration analysis. Performance and cost data were then used to do a cost-effectiveness analysis.

Results.

Mean peak concentrations were higher with ODD (7.9 ± 0.2 μg/mL) than TDD (6.7 ± 0.3 μg/mL). Half of the patients in the TDD group had trough concentrations >2 μg/mL, compared with none in the ODD group. Overall, 57% of the SGCs in the TDD group were outside the target concentration range versus 7% in the ODD group. Based on questionnaire results, a total 72-hour process cost of ODD versus TDD was compared for regimens with and without use of SGC analysis. If SGCs are obtained, more than 75% of the cost associated with gentamicin therapy is attributable to SGC analysis. Based on a cost-effectiveness analysis, ODD was the dominant dosing strategy in all categories analyzed.

Conclusions.

ODD of gentamicin at 4 mg/kg in neonates ≥34 weeks' gestation is the preferable treatment strategy based on: 1) significantly improved SGC performance compared with TDD; 2) elimination of the need for routine SGC collection in infants on short courses of therapy; and 3) significant antibiotic-associated hospital cost savings when compared with conventional therapy of TDD and SGC analysis.

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