Pharmacoeconomic impact of once-daily aminoglycoside administration

A retrospective cost analysis compared hospital costs of standard gentamicin dosing and once-daily regimens in 1127 patients. Hospital costs compared were drug/supply/preparation/administration (DSPA; $4.56/500 mg once-daily dose and $3.32/100 mg every 8 hrs standard dose); therapeutic drug monitoring (TDM) ($25/gentamicin level); and nephrotoxicity management. The mean length of therapy was 4.5 days with both regimens. The mean number of blood samples drawn to measure drug levels was 0.65 for once-daily dosing and 1.7 for standard dosing. Mean DSPA and TDM costs/patient for a 4.5-day course of once-daily therapy were $20.52 and $16.25, respectively ($36.77/course of therapy). In comparison, estimated mean DSPA and TDM costs for 4.5 days standard therapy were $44.82 and $42.50, respectively ($87.32/course of therapy). We observed an overall reduction in nephrotoxicity from approximately 4% to 1.2% with the once-daily program, resulting in a nephrotoxicity management cost reduction from $182 to $55/patient exposed to aminoglycosides. The once-daily program resulted in a 58% reduction in aminoglycoside-associated hospital cost and a nephrotoxicity management savings of 70%/patient.