Extended-infusion ceftolozane-tazobactam treatment at 1.5 g every 8 h was used to treat multidrug-resistant Pseudomonas aeruginosa in a critically ill patient on continuous venovenous hemofiltration. Serum drug concentrations were measured at 1, 4, 5, 6, and 8 h after the start of infusion. Prefilter levels of ceftolozane produced a maximum concentration of drug ( C max ) of 38.57 μg/ml, concentration at the end of the dosing interval ( C min ) of 31.63 μg/ml, time to C max ( T max ) of 4 h, area under the concentration-time curve from 0 to 8 h (AUC 0–8 ) of 284.38 μg · h/ml, and a half-life ( t 1/2 ) of 30.7 h. The concentrations were eight times the susceptibility breakpoint for the entire dosing interval.
