Probability of Target Attainment Analyses to Inform Ceftolozane/Tazobactam Dosing Regimens for Patients With Hospital‐Acquired or Ventilator‐Associated Bacterial Pneumonia and End‐Stage Renal Disease Receiving Intermittent Hemodialysis

ASPECT‐NP, a phase 3 trial of ceftolozane/tazobactam in hospital‐acquired/ventilator‐associated bacterial pneumonia (HABP/VABP), excluded patients with end‐stage renal disease (ESRD). A modeling/simulation approach was undertaken to inform optimal dosing in this population, using previously developed ceftolozane and tazobactam population pharmacokinetic models informed by data from 16 clinical studies. Stochastic simulations were performed using NONMEM to support dose justification. Probability of target attainment (PTA) simulations in plasma and epithelial lining fluid were conducted using a 14‐day treatment, with hemodialysis every other weekday for a high‐dose (4X), middle‐dose (3X), or low‐dose (2X) regimen, where X was the recommended dose in patients with complicated intra‐abdominal infection/complicated urinary tract infection and ESRD (500 mg/250 mg ceftolozane/tazobactam loading dose and 100 mg/50 mg ceftolozane/tazobactam maintenance dose administered by 1‐hour infusion every 8 hours). PTA was determined using established pharmacokinetic/pharmacodynamic targets: ceftolozane, 30% of the interdose interval (8 hours) in which free ceftolozane concentration exceeded the minimum inhibitory concentration value of 4 µg/mL; tazobactam, 20% of the interdose interval in which free tazobactam concentration exceeded 1 µg/mL. Plasma PTA was >90% for both agents for all 3 regimens. Plasma ceftolozane exposures at the high‐dose regimen exceeded those from phase 3 study experience. Epithelial lining fluid PTA was >90% for high‐ and middle‐dose regimens but was <80% for tazobactam on dialysis days at the low‐dose regimen. For patients with HABP/VABP and ESRD requiring intermittent hemodialysis, the middle‐dose regimen of 1.5 g/0.75 g ceftolozane/tazobactam loading + 300 mg/150 mg maintenance every 8 hours by 1‐hour infusion is recommended.