title: Automated amidolytic method for determining heparin, a heparinoid, and a low-Mr heparin fragment, based on their anti-Xa activity.
abstract: Using the chromogenic substrate S-2222, we have optimized and automated an amidolytic assay for heparin. The assay is based on the detection of anti-Xa activity generated by heparin in plasma. The method is reproducible (intra- and interassay CVs of 2.4 and 3.3%, respectively) and reliable in antithrombin III-deficient plasma. Results of this assay, obtained for plasma samples from patients and volunteers treated with heparin, correlate well (r = 0.899) with those of the test for activated partial thromboplastin time. Upon administration of a low-Mr heparinoid (Org 10172) and heparin fragment ( Kabi 2165), however, the activated partial thromboplastin time failed to detect anticoagulant activity, whereas the chromogenic heparin assay revealed anti-Xa activity. This automated amidolytic assay for heparin is therefore suitable not only for monitoring standard therapy with heparin but also for measuring the activity of recently developed heparin fractions.
mesh_terms: D000328:Adult; D000368:Aged; D000990:Antithrombin III / Q000378:metabolism; D001322:Autoanalysis; D001792:Blood Platelets / Q000378:metabolism; D002809:Chondroitin Sulfates; D003871:Dermatan Sulfate; D005170:Factor X / Q000037:antagonists & inhibitors*; D015951:Factor Xa; D005260:Female; D006025:Glycosaminoglycans / Q000097:blood*; D006493:Heparin / Q000097:blood*; D006497:Heparan Sulfate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides; D010314:Partial Thromboplastin Time; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000990:Antithrombin III; D002809:Chondroitin Sulfates; D003871:Dermatan Sulfate; D005170:Factor X; D015951:Factor Xa; D006025:Glycosaminoglycans; D006493:Heparin; D006497:Heparan Sulfate; D009842:Oligopeptides; C015608:benzoyl-Ile-Glu-Gly-Arg-p-nitroanilide; C035838:danaparoid