Cefiderocol Elimination During Peritoneal Dialysis: A Short Report.

Cefiderocol is a siderophore cephalosporin with potent activity against multidrug-resistant Gram-negative pathogens, yet pharmacokinetic data for patients receiving peritoneal dialysis (PD) are lacking. We report the first clinical observation of cefiderocol elimination during PD, complemented by an intra-individual comparison with hemodialysis (HD) and reference measurements from a second patient not receiving dialysis. A 64-year-old man on continuous ambulatory PD received cefiderocol 2 g every eight hours as three-hour infusions. Serial sampling showed serum trough and peak concentrations of 79.8 and 139.9 mg/L. A single PD exchange reduced serum levels by 32% (from 139.9 to 95.6 mg/L) with near-complete equilibration in dialysate (94 mg/L), indicating meaningful peritoneal removal. During subsequent conversion to HD, serum concentrations declined more rapidly, consistent with higher extracorporeal clearance. A second patient with acute-on-chronic kidney injury who did not receive dialysis exhibited the highest concentrations (trough 164.9 mg/L; peak 280.1 mg/L), highlighting the impact of absent extracorporeal elimination. Treatment was clinically successful and well-tolerated in both cases, with no neurotoxicity or other adverse events observed. These findings demonstrate that PD provides moderate but consistent cefiderocol elimination, substantially less efficient than HD, and suggest that therapeutic drug monitoring may help optimize dosing and balance efficacy and safety in PD. Larger studies are warranted to refine dosing recommendations for this population.