Heparin, acid mucopolysaccharide, is produced by mast cells. It is referred to direct anticoagulants, i.e. influence directly on coagulation factors (XII, XI, X, IX, VII and
II). Heparin is used as anticoagulant for therapeutic purposes. The quantitative determination of heparin levels in plasma is useful tool for monitoring treatment efficacy.
This determination may be performed using the following anti-Xa methods: clotting assays and chromogenic assays. Antithrombin III (AT III) is the main inhibitor
of thrombin. It activates factor Xa and other serine proteinases of coagulation cascade. In normal conditions inhibition speed is low, but it rises in thousands times
in heparin presence. Heparin preparations in complex with AT III inhibit action of activated factor Xa in more level than thrombin. On this reason test for inhibition of
factor Xa activity is more sensitive and informative of all methods of detection of heparin activity in blood plasma.
Principle. Method of the detection of heparin activity is based on ability of complex AT III-heparin to neutralize
FXa. Plasma Heparin activity is determined by adding antithrombin III and FXa. At this time inhibition of
factor Xa by complex AT III–heparin proportional to heparin quantity in plasma. Residue factor Xa catalyze
detachment of pNA from synthetic chromogen substrate. Absorption of free pNA, detected at wave-length as 405 nm, is inversely proportional to heparin activity in plasma.
Process has following scheme:
AT III (surplus) + heparin ==> AT III – heparin
AT III – heparin + Xa (surplus) ==> AT III – heparin –
Xa + Xa (residue)
Substrate – pNA + Xa (residue) ==> peptide + pNA
REACHROM – HEPARIN
The kit of reagents for the determination of anti-Xa heparin
activity by photometric method
Cat. # HP-1 for 20-100 assays.
Reagents:
– buffer with heparin, concentrated (5 mL) – 2 vials
– human thrombin (2.5 mL), lyophilized (10 IU/mL) – 2 vials
– standard plasma (1 mL), lyophilized – 1 vial
– chromogen substrate (2 mL), lyophilized – 2 vials
REACLOT-HEPARIN
The kit of reagents for the determination of anti-Xa heparin activity by clotting method
Cat. # HP-2-for 40-80 assays.
The kit is intended for monitoring for heparin administration (including low molecular heparin) by the detection of its Xa
activity in human blood plasma.
Method is based on ability of small quantities of heparin in tested plasma to neutralize exogenous activated factor Xa
in antithrombin III presence.
Process has two stages:
1. inactivation of factor Xa surplus by complex AT III – heparin
2. measurement of coagulometric activity of residue factor Xa on
phospholipid membrane in presence of calcium ions.
Substrate plasma is the source of AT III, fibrinogen and factor V.
RENAPARIN
The kit of reagents for determination anti-Xa and anti-IIa activity low molecular heparin in medicament and substace.
Cat. # HP-6 for 100 assays.
