Generic low molecular weight Generic low molecular weight heparins. Are there any guidelines! heparins. Are there any guidelines!

Jawed Fareed, Ph.D.

Walter Jeske, Ph.D.Loyola University Medical Center

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.

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.

Manufacturing Process for Low Molecular WeightHeparin and Lower Low Molecular Weight Heparin

UFH

15 kDa

LMWH

4-6 kDa

Ultra LMWH

2-4 kDaPentasaccharide

1-7 kDa

Heparin derived oligosaccharides

< 2.5 kDa

Anti-Xa/IIa = 1.0

Anti-Xa/IIa = 2.5 - 7.5 Anti-Xa/IIa = 10

- 50

Anti-Xa/IIa = > 50

Depolymerization inflicts other changes

Currently Developed Generic LMWHs

1. Enoxaparin (Aventis, France)

2. Dalteparin (Pfizer, USA)

3. Tinzaparin (Leo, Denmark)4. Parnaparin

(Opocrin, Italy)

O

NHSO3-

OH

O

O

OSO3-

CO2-

OHO

O

OH

OSO3-

COO2-O

CH2OSO3-

NHSO3-

OHO O

CH2OH

O

CH2OSO3-

OH

O

OSO3-

CO2-

OHO

O

OH

OSO3-

O

CH2OSO3-

NHSO3-

OHO OHO

CO2-

n

n

Enoxaparin* C6H5CH2/Na+

*

Fraxiparin

*

*C6H5CH2/Na+

Specific Structural Features in LMWHs

Any generic product must exhibit similar structural features.

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.

Are LMWHs Different?Are LMWHs Different?

Chemical properties make each LMWH unique

This translates into pharmacological differences between LMWHs

This impacts the clinical safety and efficacy in both arterial and venous thrombosis

Molecular Weight DistributionMolecular Weight Distribution

Molecular weight (Da)23456

Cum

ula

tive p

erc

enta

ge

0

20

40

60

80

100

EnoxaparinCertoparin Parnaparin Reviparin Tinzaparin Fraxiparin Dalteparin

ACLM BCLM

ACLM = above critical length material; BCLM = below critical length material; Da = DaltonsThe relative proportion of high molecular weight components clearly differs.

• 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

LMWH Differentiation: LMWH Differentiation: Clinically Relevant AttributesClinically Relevant Attributes

Key IssueKey IssueGeneric 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?

Ongoing Issues Related to the Acceptance of LMW Heparins

1. Product classification by regulatory agencies2. Development of new guidelines covering both

the biological and chemical characterization of LMWHs

3. Citizen’s Petition from the branded manufacturers

4. Reponses to the Citizen’s Petition from generic suppliers

5. Court hearing on patents6. Congressional discussions7. Position of regulatory agencies

CurrentGenerics

Minimal Requirements For the Considerations For A Generic LMW Product

1. Comparable Pharmacopoeial Monographs

2. Pharmacological and biochemical characterization

3. Pharmacokinetic/Pharmacodynamic studies (AUC)

Lovenox and generic enoxaparins exhibit varying potencies for inhibiting thrombin-induced platelet P-selectin expression.

Effect of Various LMWHs on Platelet P-Selectin ExpressionEffect of Various LMWHs on Platelet P-Selectin Expression

USP and Anti-Fxa Potency of Various Generic LMWHsUSP and Anti-Fxa Potency of Various Generic LMWHsRelevance to TAFIa Generation InhibitionRelevance to TAFIa Generation Inhibition

Cutenox Clenox Dilutol Dripanina Lovenox

Uni

ts/m

g

0

20

40

60

80

100

120

Cutenox Clenox Dilutol Dripanina Lovenox

TA

FIa

(%

Act

ivity

)

0

20

40

60

80

100

USP (U/mg) IU/mg TAFIa (% Activity)

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 DalteparinHeparinase and Protamine Neutralization of Generic Dalteparin

Enoxaparins + 0.125U/ml UFHase, UVEnoxaparins + 0.125U/ml UFHase, UV

Gen 3Lovenox

Gen 1

Gen 2

Gen 4

AU

0.00

0.05

0.10

0.15

Minutes

31.0 33.0 35.0 37.0 39.0 41.0 43.0 45.0 47.0 49.0

Comparative MW Profile of Generic LMWHsUV detection

Enoxaparin G-AE G-AG G-AJ G-AN

% c

ompo

nent

s <

2.5

kD

a0

20

40

60

80

Pre-UFHase 0.125 U/ml UFHase 0.25 U/ml UFHase

Pre- and Post-Heparinase Molecular Profile of Various Pre- and Post-Heparinase Molecular Profile of Various Versions of EnoxaparinVersions of Enoxaparin

Comparative MW Profile of Generic LMWHsUV

Enoxaparin G-AE G-AG G-AJ G-AN

Mn

(Da)

0

500

1000

1500

2000

2500

3000

3500

Pre-UFHase 0.125 U/ml UFHase 0.25 U/ml UFHase

Anti-IIa Pre-UFHase

Conc; µg/ml

1 10 100

% I

nhib

ition

0

20

40

60

80

100

Anti-IIa 0.1 U/ml UFHase

Conc; µg/ml

1 10 100%

Inhib

ition

0

20

40

60

80

Enox 89c141 Enox 89441 Sing. Enox Cutenox 306x Cutenox 302X

Clenox Dilutol Lupenox 20 Lupenox 60 Dripanina 040478

Differential Functionality of Pre- and Post-Heparinase Digested Differential Functionality of Pre- and Post-Heparinase Digested Generic LMWHsGeneric LMWHs

Relative Neutralization of Heparins by Heparinase - UV

0

5000

10000

15000

20000

25000

Heparin OP/253(Porcine)

Heparin lot 15096(Bovine)

Heparin OP253(Bovine)

Heparin lot 17046

Mw

(D

a)

Mw Sal Mw 0.125 Mw 0.25

% 1,6-anhydrosugar0 10 20 30 40

Clo

tting

tim

e (s

ec)

40

60

80

100

120

APTT Heptest

% 1,6-anhydrosugar0 10 20 30 40

% In

hibi

tion

30

40

50

60

70

80

Anti-IIa Anti-Xa

Effect of Anhydromanno Content on the Anticoagulant Effect of Anhydromanno Content on the Anticoagulant and Antiprotease Actions of LMWHand Antiprotease Actions of LMWH

Differential Release of TFPI by Various Differential Release of TFPI by Various Generic Enoxaparins in PrimatesGeneric Enoxaparins in Primates

Lovenox Cutenox Clenox Dilutol Dripanina

TF

PI

(ng/

ml)

0

50

100

150

200

250

300 Pre Post 153%

95%

Differential Generation of Nitric Oxide by Differential Generation of Nitric Oxide by Various Generic Enoxaparins in PrimatesVarious Generic Enoxaparins in Primates

Lovenox Cutenox Clenox Dilutol Dripanina

NO

(µ

M)

0

10

20

30

40 Pre Post

Effect of Lovenox and Generic Enoxaparins Effect of Lovenox and Generic Enoxaparins in a Rabbit Stasis Thrombosis Modelin a Rabbit Stasis Thrombosis Model

Enoxaparin Cutenox Clenox Dilutol Dripanina

ED

50 (

µg/

kg)

0

20

40

60

80

100

120

Enoxaparin Cutenox Clenox Dilutol Dripanina

ED

50 (

µg/k

g)

0.0

0.5

1.0

1.5

2.0IV SC

* *

+ +

Significant differences in the antithrombotic activities of generic LMWHs were noted.

Effect of Intravenously Administered Generic LMWH Effect of Intravenously Administered Generic LMWH in a Jugular Vein Clamping Model of Thrombosisin a Jugular Vein Clamping Model of Thrombosis

Dose: 1 mg/kg IVCirculation time: 30 min.

Antithrombotic Effects of Various Generic LMWHs in a Antithrombotic Effects of Various Generic LMWHs in a Rat Laser-Induced Thrombosis ModelRat Laser-Induced Thrombosis Model

Enoxaparin Lupenox Cutenox Dripanina Dilutol Clenox Saline

# of

Las

er s

hots

0

2

4

6

8

10

Enoxaparin Lupenox Cutenox Dripanina Dilutol Clenox Saline

Ant

i-Xa

U/m

l

0.0

0.5

1.0

1.5

2.0

2.5

3.0# of Laser shots

AXa U/ml

Dose: 1 mg/kg IVCirculation time: 15 min.

Comparative Bleeding Effects of Lovenox and Generic Comparative Bleeding Effects of Lovenox and Generic Enoxaparins in a Rabbit Ear Blood Loss ModelEnoxaparins in a Rabbit Ear Blood Loss Model

Saline Enoxaparin Cutenox Clenox Dilutol Dripanina

RB

Cs (

10

^9/L

)

0

2

4

6

8

* *

+

+

Dose: 5 mg/kgCirculation time: 15 min.

Significant differences in the bleeding activities of generic LMWHs were noted.

Pharmacodynamics of the Actions of Branded Enoxaparin and Its Generic Versions in Primates

Dosage: 100 U/kg IV

Time (min)

0 60 120 180 240 300 360 420 480

AX

a (U

/ml)

0

1

2

3

Lovenox Cutenox Clenox Lupenox Dripanina Dilutol

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

Pharmacodynamics of the Actions of Branded Enoxaparin and Its Generic Versions in Primates

Dosage: 100 U/kg SC

Time (min)

0 180 360 540 720 900 1080 1260 1440

AX

a (U

/ml)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4 Lovenox Cutenox Clenox Lupenox Dripanina Dilutol

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

Pharmacodynamics of the Actions of Branded Enoxaparin and Its Generic Versions in Primates

Dosage: 100 U/kg IV

Time (min)

0 60 120 180 240 300 360 420 480

TF

PI (

ng/m

l)

20

40

60

80

100

120

140

160

180

200Lovenox Cutenox Clenox Lupenox Dripanina Dilutol

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

Pharmacodynamics of the Actions of Branded Enoxaparin and Its Generic Versions in Primates

Dosage: 100 U/kg SC

Time (min)

0 180 360 540 720 900 1080 1260 1440

TF

PI (

ng/m

l)

40

60

80

100

120

140

160

180

200Lovenox Cutenox Clenox Lupenox Dripanina Dilutol

AUC for TFPI release markedly differed among generic products.

Pharmacodynamics of the Actions of Branded Enoxaparin and Its Generic Versions in Primates

Dosage: 100 U/kg SC

Lovenox Cutenox Clenox Lupenox Dripanina Dilutol

TA

FI (

PE

U/m

l)

0.0

0.2

0.4

0.6

0.8

1.0

TAFI inhibition differed significantly among generic LMWHs.

Pharmacodynamic Differentiation of Pharmacodynamic Differentiation of Generic Versions of LMWHsGeneric 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.

Pharmacodynamic Differentiation of Pharmacodynamic Differentiation of Generic Versions of LMWHsGeneric 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).

Do Generic LMWHs Comply with FDA Do Generic LMWHs Comply with FDA Standards for Generic Approval?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.

Generic LMW HeparinsGeneric LMW HeparinsGuideline DevelopmentGuideline Development

A. Origin of the starting material (UFH or crude heparin) / species specifications

B. Manufacturing process / patent adherence

C. Molecular and structural characterization

D. Biophysical and biochemical profile

E. Pharmacological profile

a. Animal models

b. PK/PD in humans

F. 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!

Unresolved Issues in the Development of Generic Low Molecular Weight Heparins.

1. Current guidelines for generic drugs are not valid for the acceptance of generic LMWHs.

2. LMWHs are complex multicomponent drugs requiring revised guidelines for genericization.

3. LMWHs are chemically modified complex natural glycosaminoglycans with individual profiles.

4. Bioassay specifications only require partial characterization and are not valid for LMWHs.

5. Xa and AIIa only represent partial pharmacological activities and do not represent total pharmacodynamic profile.

6. Pharmacokinetics of oligosaccharide components are composition dependent.

7. No requirements for raw material specifications.

ConclusionsConclusions• 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.