Evaluating outcomes associated with alternative dosing strategies for piperacillin/tazobactam: a qualitative systematic review.

OBJECTIVE: To perform a qualitative systematic review of the evidence comparing traditional strategies against prolonged intermittent or continuous infusion strategies for piperacillin/tazobactam, based on clinical and pharmacodynamic outcomes. DATA SOURCES: MEDLINE (1950-September 2011), EMBASE (1980-September 2011), and International Pharmaceutical Abstracts (1970-September 2011) were searched, using the terms piperacillin, tazobactam, pharmacokinetics, pharmacodynamics, dosing, and infusion. Reference lists from relevant publications were also reviewed. STUDY SELECTION AND DATA EXTRACTION: Articles evaluating the administration of piperacillin/tazobactam to adults and comparing at least 2 dosing regimens (1 of which included the traditional, manufacturer-recommended 30-minute infusion; the other, a prolonged or continuous infusion strategy) were included. Prespecified clinical outcomes of interest included mortality, clinical cures, and adverse events. The pharmacodynamic endpoint of interest was percent time of unbound drug concentration remaining above the minimum inhibitory concentration. DATA SYNTHESIS: Twelve studies were included in this review, 7 of which assessed clinical outcomes and 5 that assessed pharmacodynamic endpoints using Monte Carlo simulations. Prolonged or continuous infusions of piperacillin/tazobactam consistently achieved higher pharmacodynamic endpoints than did traditional infusions. The association of prolonged or continuous infusions with improved clinical outcomes, however, is unclear. Two retrospective studies found improved mortality rates with prolonged infusions (1 in a subgroup of patients with higher APACHE II [Acute Physiology and Chronic Health Evaluation II] scores), while another retrospective study found improved clinical cure rates with continuous infusions in patients with ventilator-associated pneumonia. These clinical benefits have not been substantiated in prospective randomized trials. No study has provided evidence of reduced adverse effects with prolonged or continuous infusions.
CONCLUSIONS: The limited evidence available does not firmly support widespread adoption of administering piperacillin/tazobactam as prolonged intermittent or continuous infusions to improve clinical outcomes despite the achievement of higher pharmacodynamic targets in simulated studies. Retrospective studies indicate that critical care patients are the subgroup most likely to benefit from these dosing strategies. Well-designed prospective clinical trials are required to confirm potential benefits observed in retrospective studies.