A Population Pharmacokinetic Analysis for Piperacillin/Tazobactam in Patients with End-Stage Kidney Disease Undergoing Intermittent Haemodialysis: Extension of a General-Purpose Model.

BACKGROUND AND OBJECTIVE

End-stage kidney disease (ESKD) patients undergoing haemodialysis (HD) require a dosing regimen that balances the low endogenous clearance with the additional dialyser clearance. This study aimed to expand a previously proposed general-purpose pharmacokinetic model for piperacillin/tazobactam with a new population of ESKD patients undergoing intermittent high-flux haemodialysis.

METHODS

Inter- and intradialytic blood samples were collected in ESKD patients undergoing intermittent high-flux haemodialysis, in HD or haemodiafiltration (HDF) mode, who received piperacillin/tazobactam during routine care. The previous general-purpose model was expanded to reflect changes in the pharmacokinetics in the new patient population. A covariate search was performed focussing on factors that explained variability between patients in endogenous and dialysis clearance. Simulations were performed to determine the probability of target attainment with current dosing recommendations in this specific population.

RESULTS

In 20 ESKD patients, 195 piperacillin/tazobactam concentrations were determined. The general-purpose model was successfully expanded, wherein endogenous piperacillin/tazobactam clearance in patients with/without residual diuresis was 63% (95% confidence interval [CI] 49.5-73.0%) and 78.6% (95% CI 66.3-86.4%) lower compared with the general population, respectively. Extraction ratios of piperacillin and tazobactam ranged from 64 to 80%. Differences in probability of target attainment (PTA) for piperacillin were observed between patients with normal kidney function and ESKD patients undergoing haemodialysis with current dosing recommendations.

CONCLUSION

We successfully expanded a general-purpose model to reflect the piperacillin/tazobactam pharmacokinetics in ESKD patients undergoing intermittent haemodialysis using high-flux dialysers. The current dosing recommendations provide inconsistent probability of target attainment in ESKD patients compared with the general population.