Pharmacokinetics and dialytic clearance of baricitinib during in vivo continuous venovenous haemodialysis in a patient with COVID-19.

Objectives: To date, there are no published pharmacokinetic (PK) data for baricitinib in critically ill patients requiring continuous renal replacement therapy. This paper describes in detail the plasma PK and dialytic clearance of baricitinib in a patient infected with coronavirus disease 2019 (COVID-19) requiring continuous renal replacement therapy in order to suggest dosing strategies in this population.
Methods: Baricitinib 2 mg daily was used for the treatment of COVID-19 in a critically ill patient on continuous venovenous haemodialysis (CVVHD). Prefiltration plasma drug concentrations of baricitinib were measured at hours 1, 2, 12, and 24 after drug administration. Postfiltration and ultrafiltrate concentrations were collected at hour 24.
Results: Plasma PK parameters of baricitinib in this patient were as follows: maximum plasma concentration (C _max ), 20.98 ng/mL; minimum plasma concentration (C _min ), 9.84 ng/mL; half-life (t _1/2 ), 23.85 h; apparent volume of distribution at the steady state (V _ss ), 99.42 L; total clearance at the steady state (CL _ss ), 2.89 L/h; and area under the concentration-time curve (AUC _0-∞ ), 692.14 ng · h/mL. The saturation coefficient for baricitinib at 24 h after administration was 0.607. The transmembrane clearance of baricitinib by CVVHD running at a flow rate of 2 L/h was 1.21 L/h, representing 41.9% of the total clearance of baricitinib.
Conclusions: In a critically ill COVID-19 patient on CVVHD, a 2-mg dose of baricitinib achieves a C _max comparable with healthy subjects, but total clearance was reduced to about 20%. Larger studies exploring multiple patients and dialysis modes are needed to determine the optimal dosing strategy for baricitinib in this patient population.
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