Drug therapy in continuous ambulatory peritoneal dialysis patients.

Transport of solutes across the peritoneal membrane in continuous ambulatory peritoneal dialysis (CAPD) is determined by patient-related factors (concentration gradient, membrane surface area, blood flow and membrane permeability) and by drug-related factors (charge on the molecule, protein binding, molecular weight, lipophilicity). On the basis of the chemical properties of a drug a prediction of the peritoneal clearance rate in CAPD patients is given, by the formula CLCAPD = 75 square root free fraction/molecular weight. The implications of this formula are discussed. It is concluded that usually it is not necessary to change the dose as compared with end-stage renal disease patients who are not treated with CAPD.