Antimicrobial practice. Development of guidelines for gentamicin dosing.

The performance of dosage guidelines for starting gentamicin therapy was evaluated prospectively in 50 patients with suspected or proven Gram-negative septicaemia and the results were compared with results from similar group of 50 patients for whom the guidelines were not followed. Peak concentrations were significantly higher when the guidelines were followed (7.2 (+/- 1.9) mg/L vs 5.7 (+/- 1.8) mg/L) but there was no difference in trough concentrations. Fifty-eight per cent of patients had both peak and trough concentrations within the target range (peak > 5 mg/L, trough < 2 mg/L) when doses were decided empirically; this increased to 96% when the guidelines were followed. However, use of the guidelines achieved peaks of > 7 mg/L in only 56% of patients. A revised protocol with higher doses given less frequently was therefore developed and a prospective assessment of its performance indicated that satisfactory concentrations were obtained in 96% of patients.