Drastic reduction of piperacillin-tazobactam concentrations in an in-vitro model of continuous venovenous hemofiltration: proposal of an innovative modality of administration to maintain them at constant concentration.

BACKGROUND/AIMS: Critically-ill patients often undergo continuous renal replacement therapy (CRRT) and need antimicrobial therapy. Piperacillin and tazobactam (Pip-Tzb) are cleared by CRRT. Our aim is to evaluate Pip-Tzb removal in an in-vitro-single-pool-model of continuous-veno-venous-hemofiltration (CVVH); we test a new method of Pip-Tzb administration during CRRT assuring constant levels of concentrations above the minimum inhibitory concentration (MIC).

METHODS: In an in-vitro-single-pool-model of CVVH, two solutions (Protein-Free-Solution, PFS and Fresh-Frozen- Plasma, FFP) added with Pip-Tzb were tested for Pip-Tzb removal and adsorption. Then, to keep concentrations constantly above the MIC during CVVH, we add Pip-Tzb in the reinfusion bags.

RESULTS: Pip-Tzb rapidly decreased than the MIC during CVVH. The adsorption was irrelevant in the test with FPS. Adding Pip-Tzb in the reinfusion bags of the CVVH system, we observed constant concentrations of Pip-Tzb over time.

CONCLUSION: The association of Pip-Tzb is rapidly cleared with a real risk of inadequate dosages in patients undergoing CRRT. Adding Pip-Tzb in the reinfusion bags above the MIC, we obtained stability of concentrations during CVVH.