Pharmacokinetic and economic evaluation of piperacillin/tazobactam administered as either continuous or intermittent infusion with once-daily gentamicin

With increasing use of once-daily aminoglycoside dosing and renewed interes t in continuous infusions of p-lactam agents, there is a need to study the interaction between aminoglycosides and penicillins as it relates to these nontraditional dosing regimens. Twelve healthy volunteers each received a c ontinuous (500 mg/h based on the piperacillin component) and an intermitten t (4.5 g q6h) infusion of piperacillinAazobactam with and without a single high dose of gentamicin (7 mg/kg). The effect of gentamicin on the serum co ncentration of the piperacillin component was measured for each dosing regi men. Continuous infusion of piperacillin/tazobactam resulted in a mean stea dy-slate piperacillin concentration of 28.0 mu g/mL. The piperacillin conce ntration, after the simultaneous 1-hour infusion of gentamicin, was statist ically unchanged at 29.7 mu g/mL. After intermittent administration of pipe racillin/tazobactam, piperacillin's maximum concentration, half-life, and a rea under the concentration-time curve were 232 mu g/mL, 0.81 hours, and 35 4 mu g . h/mL, respectively, These pharmacokinetic values were also statist ically unchanged when a concomitant dose of gentamicin was given, Gentamici n concentrations were not affected by either dosing method of piperacillin/ tazobactam. Administering once-daily gentamicin to volunteers receiving pip eracillin/tazobactam by continuous infusion or by intermittent dosing does not alter the pharmacokinetic parameters of piperacillin or gentamicin. Com pared with intermittent infusion, continuous infusion results in lower cost s, mainly from a reduction in labor and supply costs.