Low molecular weight heparin in haemodialysis for chronic renal failure: dose finding study of CY222

A dose finding study of the very low molecular weight heparin CY222 (MW 2500) in patients (n = 8) with chronic renal failure undergoing dialysis has been carried out to (i) establish an effective dose and (ii) determine the relationship between ex vivo anti-factor Xa levels in plasma and the anticoagulant effect (in vivo suppression of FPA levels). Doses of CY222 were compared to a dose (5000 iu bolus + 1500 iu/hr) of unfractionated heparin (UFH) that has been shown to suppress FPA levels during prolonged (greater than 5 hr) dialysis (Ireland et al., J Lab Clin Med 103, 643, 1984). CY222 given iv in increasing doses produced a dose related increase in anti-factor Xa levels (measured as Institute Choay u/ml, with CY222 itself as standard) and suppression of FPA levels. When given in its highest dose, 20,000 Institute Choay u bolus + 1500 Institute Choay u/hr, there was little effect upon KCCT, FPA levels were statistically indistinguishable from those of the UFH regime (indicating comparable anticoagulant effect), but anti-factor Xa levels (expressed in Institute Choay u/ml) were 2-3 times those of UFH (expressed in iu/ml). All samples were also assayed for anti-factor Xa level against the proposed low MW Heparin Standard. Plasma levels of CY222 were then found to be 2.78 times lower, so that the anti-factor Xa levels of CY222 required to produce comparable anticoagulant effect were then indistinguishable from those of UFH.(ABSTRACT TRUNCATED AT 250 WORDS)