Anticoagulant Therapy

ACTICHROME® Heparin (Anti-FIIa) is an amidolytic chromogenic assay intended for the quantitative determination of therapeutic heparin in human plasma via the measurement of Factor IIa (thrombin) activity. The inhibitory effect of antithrombin III (ATIII) on Factor IIa (thrombin), Factor Xa, and other coagulation serine proteases in plasma is increased several thousand-fold by heparin. This inhibition accounts for the anticoagulant effect of heparin. Assaying plasma heparin levels by the measurement of their Anti-Factor IIa activity is a necessary tool for monitoring the efficacy of heparin treatment efficacy. Low molecular weight heparin (LMWH) preparations appear to catalyze the reaction between thrombin (FIIa) and AT-III less readily than the reaction between Factor Xa and AT-III. Unfractionated heparin (UFH) catalyzes both reactions equally.

ACTICHROME Heparin (Anti-FIIa) is a three stage assay. First, plasmas containing heparin incubate with human antithrombin III forming a heparin- ATIII complex. Second, thrombin is added which is inhibited by the heparin-ATIII complex. Last, the residual thrombin activity hydrolyzes SPECTROZYME® TH, a thrombin specific chromogenic substrate. As both thrombin and antithrombin III are in excess, the residual thrombin activity measured is inversely proportional to the heparin concentration in the plasma.

ACTICHROME® Heparin (Anti-FXa) is an amidolytic chromogenic assay intended for the quantitative determination of therapeutic heparin in human plasma via the measurement of Factor Xa activity.The inhibitory effect of antithrombin III (ATIII) on Factor IIa (thrombin), Factor Xa, and other coagulation serine proteases in plasma is increased several thousand-fold by heparin. This inhibition accounts for the anticoagulant effect of heparin. Assaying plasma heparin levels by the measurement of their Anti-Factor Xa activity is a necessary tool for monitoring the efficacy of heparin treatment efficacy. Low molecular weight heparin (LMWH) preparations appear to catalyze the reaction between thrombin (FIIa) and AT-III less readily than the reaction between Factor Xa and AT-III. Unfractionated heparin (UFH) catalyzes both reactions equally. ACTICHROME Heparin (Anti-FXa) is a three stage assay. First, plasmas containing heparin incubate with human antithrombin III forming a heparin- ATIII complex. Second, Factor Xa is added which is inhibited by the heparin-ATIII complex. Last, the residual Factor Xa activity hydrolyzes SPECTROZYME® FXa, a Factor Xa specific chromogenic substrate. As both Factor Xa and antithrombin III are in excess, the residual Factor Xa activity measured is inversely proportional to the heparin concentration in the plasma.

The IMUCLONE™ Platelet Factor 4 ELISA is an enzyme-linked immunosorbent assay for measuring human Platelet Factor 4 in platelet depleted plasma, or in any biological fluid where Platelet Factor 4 may be present. Platelet Factor 4 (PF4) is a 70 amino acid (molecular weight of 7,800) protein released from the alphagranules of activated platelets complexed with platelet proteoglycan. Upon release, the half-life of PF4 is very short, less than 5 minutes, as it quickly binds to endothelial cell glycosaminoglycans where it is stored. Its major physiologic role appears to be the neutralization of heparin-like molecules on the endothelial surface of blood vessels. PF4 possesses a powerful anti heparin activity, binding to heparin with a high affinity, where 1 mg of PF4 will inhibit 27 IU of heparin. This anti-heparin activity translates to lower antithrombin III activity which promotes coagulation. The PF4 concentration in normal human plasma is less than 10 IU/mL. Heparin administration causes PF4 to be released from its endothelial cell storage sites, greatly increasing its concentration in blood.