21 January 2020
Background: Clonidine is an α<sub>2</sub>-agonist that is commonly used for sedation in the intensive care unit. When patients are on continuous venovenous hemofiltration (CVVH) in the presence of kidney dysfunction, the sieving coefficient of clonidine is required to estimate how much drug is removed by CVVH. In the present study, we measured the sieving coefficient of clonidine in critically ill, ventilated patients receiving CVVH. Methods: A total of 20 samples of plasma and ultrafiltrate of 3 patients on CVVH, using a standard 1.5 m<sup>2</sup> polyacrylonitrile AN69 membrane, during continuous clonidine infusion were collected. After correction for the effect of predilution, we calculated the sieving coefficient for clonidine. Results: The mean sieving coefficient of clonidine was 0.52 (SD 0.097). Conclusion: Using a polyacrylonitrile AN69 membrane in a CVVH machine, the in vivo sieving coefficient of clonidine was 0.52.