Cost Analysis of Pharmacy-Based Aminoglycoside Regimens: Once-Daily vs. Multiple Daily Dosing

Abstract

A retrospective, case-controlled cost analysis was performed to compare the aminoglycoside-related costs of pharmacy-managed once-daily (ODA) and multiple-daily (MDA) gentamicin dosing in 274 patients. Outcome measures included the amount of drug and infusion-related supplies consumed, length of therapy, number of drug levels performed, and occurrence of nephrotoxicity. Costs were calculated based on outcome measures. Characteristics related to demographics, renal function, and site of infection were similar for both groups. The mean cumulative gentamicin dose per patient was greater in the ODA group (2223 mg) as compared with the MDA group (1169 mg), but median duration of therapy was similar in both groups (4 days). The ODA group required significantly fewer drug assays per patient than the MDA group (0.39 ± 0.63 and 1.1 ± 1.2, respectively; p < 0.01). Nephrotoxicity occurred in 1.4% of ODA patients and in 3% of MDA patients (p > 0.05). The mean costs per patient for the ODA and MDA groups were $85.66 and $140.61, respectively. Once-daily dosing of gentamicin was associated with a 65% reduction in therapeutic drug monitoring, a 53% reduction in rate of nephrotoxicity, and an overall reduction of 39% in total aminoglycoside-related costs (excluding cost of labor).]