Author(s): Finnell DL, Davis GA, Cropp CD, Ensom MH
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Abstract OBJECTIVE: To validate the Hartford nomogram for once-daily aminoglycoside dosing in trauma surgery patients. METHODS: A chart review was performed in trauma surgery patients who were started on once-daily aminoglycoside therapy. A peak aminoglycoside concentration was drawn 30 minutes after the end of the first or second infusion, and a random concentration was drawn approximately 10 hours after the dose. The 10-hour random concentration was used to validate the Hartford nomogram by predicting the actual dosing interval (determined by extrapolating the peak and random concentrations to achieve a trough concentration <1 mg/L). The percentage of intervals accurately predicted by the nomogram was determined. RESULTS: Forty-nine patients (34 men and 15 women), age 43.0+/-15.9 y, total body weight 81.3+/-24.5 kg, ideal body weight 68.1+/-10.7 kg, dosing body weight (DBW) 72.0+/-14.4 kg, and estimated creatinine clearance [Cl(cr)] 89.5+/-20.6 mL/min/1.73 m2 were evaluated. Patients received 505+/-105 mg (7.0+/-0.4 mg/kg) of either gentamicin or tobramycin per dose. The concentration 30 minutes after the infusion was 22.4+/-5.9 mg/L, the concentration at the end of the dosing interval was 0.20+/-0.46 mg/L, the 10-hour random concentration was 2.6+/-1.8 mg/L, the elimination rate constant was 0.26+/-0.08 h(-1), the elimination half-life was 3.0+/-1.2 hours, and the volume of distribution was 19.9+/-7.9 L (0.28+/-0.09 L/kg of DBW). Ninety-eight percent (48/49) of the intervals were accurately predicted by the nomogram. CONCLUSIONS: In trauma surgery patients with Cl(cr) of more than 60 mL/min/1.73 m2, the Hartford nomogram using a single random aminoglycoside concentration accurately predicted the same once-daily aminoglycoside intervals as determined by two concentrations. Less aggressive therapeutic drug monitoring in this patient subpopulation can lead to significant cost savings.
This article was published in Ann Pharmacother
and referenced in Pharmaceutica Analytica Acta