Guidelines for Low Molecular Weight Heparins – Generic Drugs

1. Generic low molecular weight heparins. Are there any guidelines! Jawed Fareed, Ph.D.Walter Jeske, Ph.D.Loyola University Medical Center

2. What are Generic Drugs?A generic drug is identical, or bioequivalent to a brand name drug in dosage form, safety, strength, route of administration, quality, performance characteristics and intended use. Although generic drugs are chemically identical to their branded counterparts, they are typically sold at substantial discounts from the branded price. According to the Congressional Budget Office, generic drugs save consumers an estimated $8 to $10 billion a year at retail pharmacies.

3. Is a Generic Drug Available for a Brand Name Drug? • You can search for generic equivalents by using the "Electronic Orange Book" at http://www.fda.gov/cder/ob/default.htm and search by proprietary "brand" name," then search again by using the active ingredient name. If other manufacturers are listed besides the "brand name" manufacturer when searching by the "active ingredient," they are the generic product manufacturers. • Generic versions of heparin, aspirin, warfarin and streptokinase are available. In some countries Generic versions of LMWHs are available.

4. Manufacturing Process for Low Molecular Weight Heparin and Lower Low Molecular Weight Heparin Anti-Xa/IIa = 1.0 UFH 15 kDa Anti-Xa/IIa = 2.5 - 7.5 Anti-Xa/IIa = 10 - 50 Heparin derived oligosaccharides < 2.5 kDa LMWH 4-6 kDa Anti-Xa/IIa = > 50 Ultra LMWH 2-4 kDa Depolymerization inflicts other changes Pentasaccharide 1-7 kDa

5. Currently Developed Generic LMWHs 1. Enoxaparin (Aventis, France) 2. Dalteparin (Pfizer, USA) 3. Tinzaparin (Leo, Denmark) 4. Parnaparin (Opocrin, Italy)

6. n n Specific Structural Features in LMWHs * * C6H5CH2/Na+ Enoxaparin 1 2 * Fraxiparin *C6H5CH2/Na+ Any generic product must exhibit similar structural features.

7. Is Chemical Characterization of Branded LMWHs Sufficient to Satisfy Assure Pharmacodymamics Equivalence? No. Because LMWHs are hybrid products of biologic origin with chemical modifications. Moreover the starting material is more important to characterize for product consistency.

8. Are LMWHs Different? Chemical properties make each LMWH unique This translates intopharmacological differences between LMWHs This impacts theclinical safety and efficacy in both arterial and venous thrombosis

9. ACLM BCLM 100 80 60 Cumulative percentage Enoxaparin Certoparin 40 Parnaparin Reviparin Tinzaparin 20 Fraxiparin Dalteparin 0 6 5 4 3 2 Molecular weight (Da) Molecular Weight Distribution ACLM = above critical length material; BCLM = below critical length material; Da = Daltons The relative proportion of high molecular weight components clearly differs.

10. LMWH Differentiation: Clinically Relevant Attributes • Structural differences ………….……. May impact PK/PD • Molecular size………..………………. May impact anti-Xa, anti-IIa • Charge density …………………………Interaction with cells • Binding to ATIII………………………..Antithrombotic effects • Binding to HCII………… …………….Anticoagulant effects • Ability to release TFPI……………….. Inhibition of formed TF • Interaction with proteins …………….. Decreased PK/PD • Interactions with cells ………………..Signaling effects (not understood) • Ability for glycosylation ……………… Biological amplification • Vascular uptake ………………………Antithrombotic surface • Endovascular uptake ………………..Inhibition of vascular proliferation • Modulation of growth factors ………...Anti-cancer, anti-apoptotic, anti- angiogenic • Molecular effects ……………………..Genotypic expression changes • Regulatory effects…………………….Molecular and cellular effects

11. Key Issue Generic drugs must contain the same active ingredient as the innovator drug and must be bioequivalent in terms of their PK/PD profile.While straight-forward for small molecule drugs, demonstrating sameness is much more difficult for drugs whose active ingredients are complex mixtures. Are the current regulatory guidelines regarding the characterization of LMWHs adequate to ensure that generic LMWHs are, in fact, the same as the innovator drug?

12. Ongoing Issues Related to the Acceptance of LMW Heparins • Product classification by regulatory agencies • Development of new guidelines covering both the biological and chemical characterization of LMWHs • Citizen’s Petition from the branded manufacturers • Reponses to the Citizen’s Petition from generic suppliers • Court hearing on patents • Congressional discussions • Position of regulatory agencies

13. Current Generics

14. Minimal Requirements For the Considerations For A Generic LMW Product • Comparable Pharmacopoeial Monographs • Pharmacological and biochemical characterization • 3. Pharmacokinetic/Pharmacodynamic studies (AUC)

15. Lovenox and generic enoxaparins exhibit varying potencies for inhibiting thrombin-induced platelet P-selectin expression. Effect of Various LMWHs on Platelet P-Selectin Expression

16. USP and Anti-Fxa Potency of Various Generic LMWHsRelevance to TAFIa Generation Inhibition

17. * ** Neutralization of Dalteparin and Daltehep by 0.1 U/ml heparinase-I (left) and 25 µg/ml protamine sulfate (right). While heparinase neutralized the anticoagulant effect of Dalteparin and Daltehep to a comparable level, protamine was not as effective at inhibiting Daltehep. *p<0.05 vs. Daltehep; **p<0.05 vs. Dalteparin + protamine Heparinase and Protamine Neutralization of Generic Dalteparin

18. Enoxaparins + 0.125U/ml UFHase, UV 0.15 0.10 AU 0.05 0.00 31.0 33.0 35.0 37.0 39.0 41.0 43.0 45.0 47.0 49.0 Minutes Lovenox Gen 3 Gen 1 Gen 4 Gen 2

19. Pre- and Post-Heparinase Molecular Profile of Various Versions of Enoxaparin

20. Differential Functionality of Pre- and Post-Heparinase Digested Generic LMWHs

22. 120 100 80 Clotting time (sec) 60 APTT Heptest 40 0 10 20 30 40 % 1,6-anhydrosugar 80 70 60 % Inhibition 50 Anti-IIa 40 Anti-Xa 30 0 10 20 30 40 % 1,6-anhydrosugar Effect of Anhydromanno Content on the Anticoagulant and Antiprotease Actions of LMWH

23. 153% 95% Differential Release of TFPI by Various Generic Enoxaparins in Primates

24. Differential Generation of Nitric Oxide by Various Generic Enoxaparins in Primates

25. IV SC * * + + Effect of Lovenox and Generic Enoxaparins in a Rabbit Stasis Thrombosis Model Significant differences in the antithrombotic activities of generic LMWHs were noted.

26. Effect of Intravenously Administered Generic LMWH in a Jugular Vein Clamping Model of Thrombosis Dose: 1 mg/kg IV Circulation time: 30 min.

27. Dose: 1 mg/kg IV Circulation time: 15 min. Antithrombotic Effects of Various Generic LMWHs in a Rat Laser-Induced Thrombosis Model

28. Dose: 5 mg/kg Circulation time: 15 min. + + * * Comparative Bleeding Effects of Lovenox and Generic Enoxaparins in a Rabbit Ear Blood Loss Model Significant differences in the bleeding activities of generic LMWHs were noted.

29. The apparent AUC of some of the LMWHs were markedly higher than the limits for the generic drug acceptance

30. The apparent AUC of some of the LMWHs were markedly higher than the limits for the generic drug acceptance

31. Burst release of TFPI markedly differed after bolus administration of enoxaparins.

32. AUC for TFPI release markedly differed among generic products.

33. TAFI inhibition differed significantly among generic LMWHs.

34. Pharmacodynamic Differentiation of Generic Versions of LMWHs • Despite similar molecular weights and anti-Xa potencies, pharmacodynamic differences in animal models were evident between different generic LMWHs. • The inhibition of TAFIa generation in normal human plasma ranged from 42 to 63% and was not proportional to the USP potency or anti-Xa activities of the generic versions of enoxaparin. • The ED50 for antithrombotic effects (IV) ranged from 62 – 91 µg/kg for generic versions compared to 72 µg/kg for the branded product. • The ED50 for antithrombotic effects (SC) ranged from 0.9 – 1.5 mg/kg for generic versions compared to 1.3 mg/kg for the branded product.

35. Pharmacodynamic Differentiation of Generic Versions of LMWHs • The generic LMWHs produced varying degrees of antithrombotic activity in two rat models of thrombosis that were not proportional to circulating anti-Xa levels. • The relative hemorrhagic effects after a 5 mg/kg IV dosage of different generic versions of enoxaparin ranged from 2.9 to 5.6 x 10^9 RBC/L in comparison to Lovenox which was 4.1 x 10^9 RBC/L. • In primates, TFPI levels increased 95 to 153% following administration of generic LMWHs (143% for Lovenox). • In primates, NO levels increased 11 to 53% following administration of generic LMWHs (56% for Lovenox).

36. Do Generic LMWHs Comply with FDA Standards for Generic Approval? • Mean difference in bioavailability cannot differ by more than – 20% to + 25 % from innovator product. • The pharmacodynamic studies in both the IV and SC regimens for the anti-Xa, anti-IIa and TFPI release clearly show that some of the generic products do not comply with the above rule. • Similarly, the modulation of TAFI and thrombin generation inhibition assays show marked differences among generic LMWHs.

37. Generic LMW HeparinsGuideline Development • Origin of the starting material (UFH or crude heparin) / species specifications • Manufacturing process / patent adherence • Molecular and structural characterization • Biophysical and biochemical profile • Pharmacological profile • Animal models • PK/PD in humans • Clinical validation of the efficacy and safety claim EP, USP, US FDA, EMEA, WHO are debating these issues. There are no clear guidelines at this time!

38. Unresolved Issues in the Development of Generic Low Molecular Weight Heparins. • Current guidelines for generic drugs are not valid for the acceptance of generic LMWHs. • LMWHs are complex multicomponent drugs requiring revised guidelines for genericization. • LMWHs are chemically modified complex natural glycosaminoglycans with individual profiles. • Bioassay specifications only require partial characterization and are not valid for LMWHs. • Xa and AIIa only represent partial pharmacological activities and do not represent total pharmacodynamic profile. • Pharmacokinetics of oligosaccharide components are composition dependent. • No requirements for raw material specifications.

39. Conclusions • These studies suggest that the current regulatory requirements in terms of anti-Xa potency specifications and molecular weight profile may be inadequate as sole acceptance criteria for generic LMWHs. • Preliminary pharmacodynamic studies have identified differences among currently available generic versions of enoxaparin and underscore the importance of in vivo equivalence studies to validate the biosimilarity of generic versions of branded LMWHs. • Guidelines for the acceptance of generic LMWHs may include the effect of such agents on whole blood clotting times, neutralization studies, platelet function assays, TFPI release and/or animal models. • Each of the generic products may have an individual profile in a given indication. Therefore, a generic product may not be given an umbrella approval for all clinical indications and warrant validation in a given indication.