The Effects of Continuous Venovenous Hemofiltration on Immunosuppressive Drug concentrations in an Ex-Vivo Model of the critically Ill Adult: (CITRIC) study.
Chumas Lucy A LA, Wallis Steven C SC, Sumi Chandra C, Abdul-Aziz Mohd Hafiz MH et al.
The pharmacokinetics of immunosuppressive drugs during continuous kidney replacement therapy (CKRT) modalities such as continuous venovenous hemofiltration (CVVH) are poorly understood, yet these drugs are crucial for transplant and critically ill patients. An ex vivo adult CVVH circuit with AN69ST membrane was established, using whole blood (WB) or blood-crystalloid (BC) to simulate hypoproteinemia and anemia, across a range of ultrafiltration rates (UFR) (1000-4000 mL/h) and point-of-dilution. Study drugs (tacrolimus, ciclosporin, mycophenolic acid (MPA), hydrocortisone, and methylprednisolone) were administered at clinically relevant concentrations. Drug concentrations were quantified by ultra-high-performance liquid chromatography-tandem mass spectrometry, and sieving coefficient (Sc) and clearance (Cl) were calculated. Mean Sc and Cl were significantly higher for BC than WB: methylprednisolone (Sc: 0.44 vs. 0.19 p < 0.001; Cl: 17.31 mL/min vs. 6.99 mL/min p < 0.001), hydrocortisone (Sc: 0.20 vs. 0.09 p = 0.005; Cl: 7.12 mL/min vs. 3.15 mL/min p = 0.01), MPA (Sc: 0.05 vs. 0.02 p < 0.001; Cl: 1.83 mL/min vs. 0.71 mL/min p < 0.001), ciclosporin (Sc: 0.00 vs. 0.00 p = 0.008; Cl: 0.02 mL/min vs. 0.01 mL/min p = 0.004). Tacrolimus was undetectable in ultrafiltrate. Point-of-dilution had minimal effect, except at UFR 4000 mL/h where pre-dilution increased MPA and methylprednisolone clearance. Hydrocortisone and methylprednisolone were cleared by CVVH, while tacrolimus, ciclosporin, and MPA Cl were negligible or absent. Hypoproteinemia and anemia significantly increased drug Cl. These findings provide mechanistic insights and support the need for validation in clinical studies to guide dosing during CKRT.