Scientific considerations in the regulatory approval of generic (or biosimilar) version of enoxaparin sodium - A lifesaving carbohydrate polymer.

Enoxaparin sodium (Clexane®/Klexane®/Lovenox®) is one amongst the few drugs that have assumed a central role as drug of treatment and/or prevention against thromboembolic complications during COVID-19. The increase in demand resulting in many generic (or biosimilar) versions entering the market has increased the risks of quality and safety (including immunogenicity) related issues. Under the circumstances, development of stringent regulatory approaches has received much attention as investigation of new drug delivery systems for improved therapeutic activity. As one of the measures to increase quality testing and ensure uninterrupted supply of this life-saving drug globally, determination of enoxaparin molecular weight (MW) has been added in the United States Pharmacopoeia (USP) monograph for enoxaparin sodium. In addition, the presence of a unique 1,6-anhydro-ring structure at the reducing end of about 15-25% of the poly (oligo) saccharide chains of the generic (or biosimilar) product has been set as a mandatory requirement. This article presents an overview of the scientific considerations in the quality manufacturing and testing of the generic (or biosimilar) enoxaparin for regulatory review and approval. In certain cases of strong analytical similarity (structural and functional), abandonment of in vivo testing in animals and humans represents a major advancement in the approval of generic (or biosimilar) version of innovator enoxaparin sodium (lovenox®, injections).

Update on Brazilian biosimilar enoxaparins.

INTRODUCTION: Brazil is among the first countries approving the commercialization and clinical use of biosimilar enoxaparins. Our research group has performed quality control assessments of these drugs over the last decade. Areas covered: We have not found noticeable differences between Brazilian biosimilar enoxaparins and the original product regarding their physicochemical properties, disaccharide composition, anticoagulant activity, bioavailability and safety. Expert commentary: In spite of clinical and pharmacological advantages of enoxaparin, subcutaneous formulations of unfractionated heparin are employed by the Brazilian public health system for prevention and treatment of thromboembolism. The underuse of both original and biosimilar enoxaparins in Brazil directly correlates with their high cost.

Analytical comparison of a US generic enoxaparin with the originator product: The focus on comparative assessment of antithrombin-binding components.

Enoxaparin sodium, a low-molecular-weight heparin (LMWH) prepared from porcine intestinal heparin, is widely used for the prevention and treatment of venous thromboembolism. The antithrombotic activity of heparin is mediated mainly through its activation of antithrombin (AT) and subsequent inhibition of coagulation factors. Heparin is a complex heteropolymer and the sulfation pattern of its alternating uronic acid and glucosamine sugar units is a major factor influencing its biological activity. The manufacturing process itself is associated with the introduction of exogenous microheterogeneities that may further affect its biological efficacy. This is important since enoxaparin is prepared by depolymerizing the heparin with the aim of optimizing its biological activity and safety. Changes during its manufacture could thus affect its biological activity and safety. The current study was performed to assess potential differences between the originator enoxaparin and a new generic enoxaparin commercialized by Teva. Heparinase digestion, AT affinity chromatography, gel permeation chromatography, anion exchange chromatography, and nuclear magnetic resonance methodologies were used. The results indicated differences in oligosaccharides related to the cleavage selectivity around the heparin AT-binding sequences of the Teva Enoxaparin Sodium Injection, USP and the originator Sanofi enoxaparin. These differences influence the strength of the AT-binding affinity of the individual oligosaccharides, their ability to activate AT and, therefore, the inhibitory potency on the proteases of the coagulation cascade. This study, together with other published analytical reports, describes specific compositional differences between generics and originator LWMHs. However, it is yet to be established whether such variations might have any clinical relevance.

Alginate coated chitosan core shell nanoparticles for oral delivery of enoxaparin: in vitro and in vivo assessment.

The objective of present research work was to develop alginate coated chitosan core shell nanoparticles (Alg-CS-NPs) for oral delivery of low molecular weight heparin, enoxaparin. Chitosan nanoparticles (CS-NPs) were synthesized by ionic gelation of chitosan using sodium tripolyphosphate. Core shell nanoparticles were prepared by coating CS-NPs with alginate solution under mild agitation. The Alg-CS-NPs were characterized for surface morphology, surface coating, particle size, polydispersity index, zeta potential, drug loading and entrapment efficiency using SEM, Zeta-sizer, FTIR and DSC techniques. Alginate coating increased the size of optimized chitosan nanoparticles from around 213 nm to about 335 nm as measured by dynamic light scattering in zeta sizer and further confirmed by SEM analysis. The performance of optimized enoxaparin loaded Alg-CS-NPs was evaluated by in vitro drug release studies, in vitro permeation study across intestinal epithelium, in vivo venous thrombosis model, particulate uptake by intestinal epithelium using fluorescence microscopy and pharmacokinetic studies in rats. Coating of alginate over the CS-NPs improved the release profile of enoxaparin from the nanoparticles for successful oral delivery. In vitro permeation studies elucidated that more than 75% enoxaparin permeated across the intestinal epithelium with Alg-CS-NPs. The Alg-CS-NPs significantly increased (p<0.05) the oral bioavailability of enoxaparin in comparison to plain enoxaparin solution as revealed by threefold increase in AUC of plasma drug concentration time curve and around 60% reduction in thrombus formation in rat venous thrombosis model. The core shell Alg-CS-NPs showed promising potential for oral delivery and significantly enhanced the in vivo oral absorption of enoxaparin.

Generic low-molecular-weight heparins: some practical considerations.

It is now widely accepted that various low-molecular-weight heparins (LMWHs) exhibit specific molecular and structural attributes that are determined by the type of manufacturing process used. For example, enoxaparin, which is prepared by benzylation followed by alkaline hydrolysis of unfractionated heparin (UFH), exhibits a double bond at the nonreducing end and the presence of a unique bicyclic structure namely 1,6 anhydromanno glucose or mannose, or both, at the reducing end. Similarly, the other LMWHs, such as dalteparin, nadroparin, tinzaparin, and parnaparin, exhibit specific structural characteristics that may contribute to their own unique biochemical and pharmacological profiles. These unique features may not exhibit any major influence on the routinely determined anti-Xa and anti-IIa activities. However, these may have an impact on the pharmacokinetics and other biological actions such as the interactions with growth factors, blood components, and vascular cells. This is the reason for the initial caution for the noninterchangeability of the anti-Xa adjusted dosing of the different LMWHs. Although the nonanticoagulant biological effects of these drugs are poorly understood at this time, they are now recognized as contributing significantly to the overall therapeutic effects of these drugs. Because some of these drugs have proved to be effective in the management of cancer-associated thrombosis and exhibit improvements in mortality outcome, these LMWHs may also produce several other effects by modulating inflammatory processes, apoptosis, and other regulatory functions related to cellular functions at different levels. Thus, the interactions of these LMWHs with antithrombin and heparin cofactor II are not the only determinants of their biological actions. Release of tissue factor pathway inhibitor (TFPI), regulation of cytokines, nitric oxide, and eicosanoids contribute to their individuality. Such properties are not only dependent on the oligosaccharide sequence and consensus sites but also depend mainly on microchemical and structural attributes in these drugs. European Pharmacopoeia (EP) and the World Health Organization (WHO) have developed guidelines to characterize these agents in terms of their molecular and biological profile. Regulatory agencies such as the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMEA) consider each of these drugs as distinct pharmacological agents. This has prompted the requirement for product-specific clinical data for the approval of their use in various clinical indications. There is a clear concern regarding the development of potential generic versions of branded products and the submissions by generic manufacturers for the regulatory approval of generic interchangeability that refers to the substitution of an apparent chemically identical and bioequivalent versions of the branded LMWHs. Currently, there are no regulatory guidelines or consensus opinions on the acceptance of generic versions of the branded products. Because the LMWHs represent not only a biological entity but also product-specific molecular and structural attributes, the acceptance of a generic version must be based on clearly defined guidelines stipulating minimal molecular and structural, biological, and clinical validation requirements. It is therefore to be stressed that each of the LMWHs is a distinct drug entity that characteristically exhibits a product-based therapeutic spectrum in different thrombotic and nonthrombotic disorders. Thus, until the establishment of valid regulatory guidelines for the generic interchangeability of the commercially available LMWHs is completed, generic substitutes are not recommended.