Hello BlueFabian, The calcitriol is a middle size molecule, 416 daltons in fact, so it could theoretically be dialyzed, HOWEVER, once given IV, only 0.4 % is present as free calcitriol, the rest is bound to plasma proteins ( 85 % to vitamin D binding protein and 14.6 % to albumin), thus the drug is not removed by the dialyzer. However the pharmaceutical company does not recommed using it anytime during duialysis. ( need in vivo studies to prove that it can be given anytine). If you are interested, you can read Lack of removal of calcitriol during hemodialysis, by Stephen Ash, Paul Gloecklner and Stephanie Barnett, published in jounal of the American Society of Nephrology in 1997, pp1587-1591. Moreover, calicitriol (calcijex) does not bind to the plastic tubing or drip chambers. This is why I wanted to know if any centers are following the CPS to a T. (We are). For the Erythopoietin, I could tell you that it has to be given in the venous port so it goes directly into the patient's blood stream because it is adsorbed to the plastic material of tubings and drip chambers. Thank you for answering my initial question.