Elimination of piperacillin and tazobactam by renal replacement therapies with AN69 and polysulfone hemofilters: evaluation of the sieving coefficient.

BACKGROUND/AIM: Piperacillin-tazobactam is commonly used to treat infections in ICU patients. Controversial data have been published about the sieving/saturation coefficient (Sc/Sa) of piperacillin during continuous renal replacement therapies (CRRT). The objective was to evaluate the Sc/Sa of piperacillin-tazobactam during continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodialysis (CVVHD) using AN69 and polysulfone.

METHODS: Ringer lactate, BSA-containing Ringer lactate and plasma were circulated at 150 ml/min. The ultrafiltrate/dialysis flow was kept at 1,500 ml/min. A bolus was injected and samples were taken. Drugs were measured using HPLC. Sc/Sa was calculated according to standard formula.

RESULTS: Free passage of drugs through the membranes was reported with protein free solutions. In the presence of proteins the Sc/Sa lowered and correlated to protein free fraction. Polysulfone had a significantly higher permeability than AN69 during CVVH.

CONCLUSION: Drug binding to albumin contributes to the decrease of the Sc/Sa of piperacillin but it does not completely justify the in vivo value obtained by some authors.