Abstract 3334

Background.

All low molecular weight heparins (LMWHs) exert their antithrombotic effect primarily via the binding of pentasaccharide domain on antithrombin but vary in physicochemical properties, anti-Xa/anti-IIa ratios, and their effect on global coagulation tests such as the inhibition of thrombin generation (TG). Definition of criteria for biological similarity between generic LMWHs and the original product is a challenging issue.

Aim of the study.

We evaluated the capacity of Lovenox® and seven generic enoxaparins to inhibit TG in platelet poor and platelet rich plasma (PPP and PRP).

Materials and Methods.

Citrated PPP and PRP from 15 healthy volunteers was spiked with increasing concentrations (2-20 μg/ml) of Lovenox®, Novex®, Enoxa®, Dilutol®, Versa®, Cutenox®, Loparin®, Fibrinox®. Platelet count in PRP was adjusted to 200 /L. The anti-Xa and anti-IIa activities in PPP were measured on STAR analyser using chomogenic assays from Diagnositca Stago. Thrombin generation in fresh PPP and PRP was triggered with PPP-reagent® and 1/200 diluted Innovin® (from Siemens) respectively and assessed with Calibrated Automated Thrombogram® (Stago, France). Mean Rate Index (MRI) of the propagation phase of TG and endogenous thrombin potential (ETP) were analysed. The enoxaparin concentrations which reduced 50% of theTG parameters (IC50) were calculated.

Results.

All studied compounds showed the same anti-Xa activity/mg and anti-Xa/anti-IIa ratio as the comparator Lovenox®. The IC50 for MRI and ETP in PPP was not significantly different between Lovenox® and each one of the generic enoxaparins. In PRP the IC50 of Lovenox® for MRI and ETP was significantly lower compared to the generic enoxaparins. The IC5O of Fibrinox®, Dilutol®, Cutenox® and Versa® was 1.5- to 2-fold higher compared to that of Lovenox® (Table 1).

Table 1.

Variability of Lovenox® and enoxaparin generics on the inhibition of TG in PRP despite their physiochemical similarities. Values are mean ± sd of 15 experiments.

Lovenox®Loparin®Enoxa®Novex®Fibrinox®Dilutol®Cutenox®Versa®
anti-Xa IU/μg 0,11 0,11 0,12 0,10 0,10 0,10 0,16 0,09 
anti-Xa/anti-IIa 3,6 2,8 3,8 3,6 2,7 4,5 3,2 3,0 
IC50 MRI PPP 2.5 ± 0.2 2.1 ± 0.1 2.3 ± 0.1 2.5 ± 0.1 2.59 ± 0.1 2.5 ± 0.1 3.3 ± 0.1 3.3 ± 0.1 
IC50 MRI PRP 6.6 ± 0.3 7.2 ± 0.2‡ 7.7 ± 0.3‡ 7.5 ± 0.1‡ 15 ± 0.1‡ 15 ± 0.2‡ 15 ± 0.1‡ 11 ± 0.2‡ 
IC50 ETP PPP 4.8 ± 0.1 3.8 ± 0.1 4.1 ± 0.1 5.1 ± 0.1 5.6 ± 0.2 5.7 ± 0.1 6.2 ± 0.2 6.6 ± 0.2 
IC50 ETP PRP 7.5 ± 0.2 9.5 ± 0.2* 10.2 ± 0.2* 10 ± 0.1* 15.5 ± 0.2* 10 ± 0.3* 11.5 ± 0.1* 15 ± 0.1* 
Lovenox®Loparin®Enoxa®Novex®Fibrinox®Dilutol®Cutenox®Versa®
anti-Xa IU/μg 0,11 0,11 0,12 0,10 0,10 0,10 0,16 0,09 
anti-Xa/anti-IIa 3,6 2,8 3,8 3,6 2,7 4,5 3,2 3,0 
IC50 MRI PPP 2.5 ± 0.2 2.1 ± 0.1 2.3 ± 0.1 2.5 ± 0.1 2.59 ± 0.1 2.5 ± 0.1 3.3 ± 0.1 3.3 ± 0.1 
IC50 MRI PRP 6.6 ± 0.3 7.2 ± 0.2‡ 7.7 ± 0.3‡ 7.5 ± 0.1‡ 15 ± 0.1‡ 15 ± 0.2‡ 15 ± 0.1‡ 11 ± 0.2‡ 
IC50 ETP PPP 4.8 ± 0.1 3.8 ± 0.1 4.1 ± 0.1 5.1 ± 0.1 5.6 ± 0.2 5.7 ± 0.1 6.2 ± 0.2 6.6 ± 0.2 
IC50 ETP PRP 7.5 ± 0.2 9.5 ± 0.2* 10.2 ± 0.2* 10 ± 0.1* 15.5 ± 0.2* 10 ± 0.3* 11.5 ± 0.1* 15 ± 0.1* 

‡ and * p<0.05 versus Lovenox.

‡ and * p<0.05 versus Lovenox.

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Conclusion.

Lovenox® and seven generic enoxaparins were the same in terms of anti-Xa activity/mg and anti-Xa/anti-IIa ratio. They exerted similar inhibitory effect on thrombin generation in PPP. In contrast, in the presence of platelets, the sameness and even the biological similarity of the studied compounds are not evident. The reasons for these diversities need to be elucidated. The results of the present study introduce the inhibition thrombin generation in platelet rich plasma as an additional biological criterion for the comparison of generic LMWHs to the innovator product.

Disclosures:

No relevant conflicts of interest to declare.

Topics:
anticoagulants, low-molecular-weight heparin, thrombin, pharmacokinetics, anti factor xa, magnetic resonance imaging, enoxaparin, antithrombin iii, antithrombins, blood coagulation tests

Author notes

*

Asterisk with author names denotes non-ASH members.

© 2010 by The American Society of Hematology
2010
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