Drug clearance by continuous haemodiafiltration. Analysis of sieving coefficients and mass transfer coefficients of diffusion.

In patients who were treated with continuous arteriovenous haemodiafiltration (CAVHD), using the AN-69 capillary dialyser, we measured the clearance rates of uraemic solutes and drugs at dialysate flow rates of 0, 1 and 3 l/h. By using a mathematical model of CAVHD, we analysed the data in terms of sieving coefficients and diffusive mass transfer coefficients. These parameters proved to be related to drug protein binding and molecular weight. The parameter values may be used to calculate the expected drug clearance rate under different operating conditions.