Bovine and porcine heparins: different drugs with similar effects on human haemodialysis

Quality control, safety assessment and preparation approaches of low molecular weight heparin

Low Molecular Weight Heparins (LMWHs) are well-established for use in the prevention and treatment of thrombotic diseases, and as a substitute for unfractionated heparin (UFH) due to their predictable pharmacokinetics and subcutaneous bioavailability. LMWHs are produced by various depolymerization methods from UFH, resulting in heterogeneous compounds with similar biochemical and pharmacological properties. However, the delicate supply chain of UFH and potential contamination from animal sources require new manufacturing approaches for LMWHs. Various LMWH preparation methods are emerging, such as chemical synthesis, enzymatic or chemical depolymerization and chemoenzymatic synthesis. To establish the sameness of active ingredients in both innovator and generic LMWH products, the Food and Drug Administration has implemented a stringent scientific method of equivalence based on physicochemical properties, heparin source material and depolymerization techniques, disaccharide composition and oligosaccharide mapping, biological and biochemical properties, and in vivo pharmacodynamic profiles. In this review, we discuss currently available LMWHs, potential manufacturing methods, and recent progress for manufacturing quality control of these LMWHs.

A Unique Enoxaparin Derived from Bovine Intestinal Heparin: A Single Purification Step of the Starting Material Assures a Bovine Enoxaparin Like the Standard from Porcine Origin

Low-molecular-weight heparin represent a significant advancement in anticoagulant therapy with enoxaparin being a prominent example obtained exclusively through the fragmentation of porcine intestinal heparin. However, escalating demand and limited resources have raised concerns about enoxaparin supplementation. The current challenge involves exploring alternative heparin sources for large-scale enoxaparin production with bovine intestinal heparin emerging as a promising option. Our study demonstrates that enoxaparin derived from the available bovine heparin preparation differs significantly from the reference compound. Yet, the implementation of a straightforward purification step yields a preparation termed "high-anticoagulant bovine heparin". Fragmentation of this purified product through β-elimination produces enoxaparin akin to the standard from a porcine origin. To ensure physicochemical similarity, we employed various spectroscopic, enzymatic, and chromatographic tests to compare the new bovine-derived enoxaparin with the original porcine compound. Biological activity was confirmed through in vitro coagulation assays and assessments using an animal model of venous thrombosis. Our study affirms that the β-elimination reaction cleaves the bovine heparin chain without preferential breaks in regions with different sulfation patterns. Additionally, we scrutinized decasaccharides purified from enoxaparin preparations, providing a comprehensive demonstration of the similarity between products obtained from porcine and bovine heparin. In summary, our findings indicate that an enoxaparin equivalent to the original porcine-derived product can be derived from bovine heparin, given that the starting material undergoes a simple purification step.

Pharmacokinetic, Hemostatic, and Anticancer Properties of a Low-Anticoagulant Bovine Heparin

Heparin is a centennial anticoagulant drug broadly employed for treatment and prophylaxis of thromboembolic conditions. Although unfractionated heparin (UFH) has already been shown to have remarkable pharmacological potential for treating a variety of diseases unrelated with thromboembolism, including cancer, atherosclerosis, inflammation, and virus infections, its high anticoagulant potency makes the doses necessary to exert non-hemostatic effects unsafe due to an elevated bleeding risk. Our group recently developed a new low-anticoagulant bovine heparin (LABH) bearing the same disaccharide building blocks of the UFH gold standard sourced from porcine mucosa (HPI) but with anticoagulant potency approximately 85% lower (approximately 25 and 180 Heparin International Units [IU]/mg). In the present work, we investigated the pharmacokinetics profile, bleeding potential, and anticancer properties of LABH administered subcutaneous into mice. LABH showed pharmacokinetics profile similar to HPI but different from the low-molecular weight heparin (LMWH) enoxaparin and diminished bleeding potential, even at high doses. Subcutaneous treatment with LABH delays the early progression of Lewis lung carcinoma, improves survival, and brings beneficial health outcomes to the mice, without the advent of adverse effects (hemorrhage/mortality) seen in the animals treated with HPI. These results demonstrate that LABH is a promising candidate for prospecting new therapeutic uses for UFH.

Pharmacokinetic, hemostatic and anticancer properties of a low-anticoagulant bovine heparin

Heparin is a centennial anticoagulant drug broadly employed for treatment and prophylaxis of thromboembolic conditions. Although unfractionated heparin (UFH) has already been shown to have remarkable pharmacological potential for treating a variety of diseases unrelated with thromboembolism, including cancer, atherosclerosis, inflammation, and virus infections, its high anticoagulant potency makes the doses necessary to exert non-hemostatic effects unsafe due to an elevated bleeding risk. Our group recently developed a new low-anticoagulant bovine heparin (LABH) bearing the same disaccharide building blocks of the UFH gold standard sourced from porcine mucosa (HPI) but with anticoagulant potency approximately 85% lower (approximately 25 and 180 Heparin International Units [IU]/mg). In the present work, we investigated the pharmacokinetics profile, bleeding potential, and anticancer properties of LABH administered subcutaneous into mice. LABH showed pharmacokinetics profile similar to HPI but different from the low-molecular weight heparin (LMWH) enoxaparin and diminished bleeding potential, even at high doses. Subcutaneous treatment with LABH delays the early progression of Lewis lung carcinoma, improves survival, and brings beneficial health outcomes to the mice, without the advent of adverse effects (hemorrhage/mortality) seen in the animals treated with HPI. These results demonstrate that LABH is a promising candidate for prospecting new therapeutic uses for UFH.

General Considerations for Diversifying Heparin Drug Products by Improving the Current Heparin Manufacturing Process and Reintroducing Bovine Sourced Heparin to the US Market

Heparin is one of the most widely used drugs in the world. It has been described as a lifesaving drug due to its roles in treating many serious diseases and illnesses including kidney dialysis, surgery, cardiac-invasive, heart attack, cardiac arrhythmia, acute coronary syndrome, pulmonary embolism, stroke, deep vein thrombosis, blood clot prevention, and many other related uses. Heparin drug products currently approved in the United States are obtained from porcine intestinal mucosa sourced from pigs, the majority of which is imported from China. However, due to the heparin contamination crisis (2008) and potential shortage and to safeguard the quality of current and future heparin supply chains including raw material, Food and Drug administration (FDA) posted a notification on its website titled “FDA Encourages Reintroduction of Bovine-Sourced Heparin”. This perspective is intended to address the history of regulatory and scientific background of heparin drug products obtained from bovine and porcine sources and general recommendations for improving the quality of current heparin manufacturing process including Critical Quality Attributes (CQA), control management, process control, related tests, limits, etc. Additionally, a general plan with systematic steps is proposed for diversifying heparin supply chains by reintroduction of bovine sourced heparin to the US market.

Techniques for Detection of Clinical Used Heparins

Heparins and sulfated polysaccharides have been recognized as effective clinical anticoagulants for several decades. Heparins exhibit heterogeneity depending on the sources. Meanwhile, the adverse effect in the clinical uses and the adulteration of oversulfated chondroitin sulfate (OSCS) in heparins develop additional attention to analyze the purity of heparins. This review starts with the description of the classification, anticoagulant mechanism, clinical application of heparins and focuses on the existing methods of heparin analysis and detection including traditional detection methods, as well as new methods using fluorescence or gold nanomaterials as probes. The in-depth understanding of these techniques for the analysis of heparins will lay a foundation for the further development of novel methods for the detection of heparins.

Preparation of Low Molecular Weight Heparin from a Remodeled Bovine Intestinal Heparin

Bovine intestinal heparins are structurally distinct from porcine intestinal heparins and exhibit lower specific anticoagulant activity (units/mg). The reduced content of N-sulfo, 3-O-sulfo glucosamine, the central and critical residue in heparin's antithrombin III binding site, is responsible for bovine intestinal heparin's reduced activity. Previous studies demonstrate that treatment of bovine intestinal heparin with 3-O-sulfotransferase in the presence of 3'-phosphoadenosine-5'-phosphosulfate afforded remodeled bovine heparin with an enhanced activity reaching the United States Pharmacopeia's requirements. Starting from this remodeled bovine intestinal heparin, we report the preparation of a bovine intestinal low molecular weight heparin having the same structural properties and anti-factor IIa and anti-factor Xa activities of Enoxaparin. Moreover, this bovine intestinal heparin-derived "Enoxaparin" showed comparable platelet factor-4 binding affinity, suggesting that it should exhibit similarly low levels of heparin induced thrombocytopeneia, HIT.

Advances in the preparation and synthesis of heparin and related products

Heparin is a naturally occurring glycosaminoglycan from livestock, principally porcine intestine, and is clinically used as an anticoagulant drug. A limitation to heparin production is that it depends on a single animal species and potential problems have been associated with animal-derived heparin. The contamination crisis in 2008 led to a search for new animal sources and the investigation of non-animal sources of heparin. Over the past 5 years, new animal sources, chemical, and chemoenzymatic methods have been introduced to prepare heparin-based drugs. In this review, we describe advances in the preparation and synthesis of heparin and related products.

Imminent risk of a global shortage of heparin caused by the African Swine Fever afflicting the Chinese pig herd

Most of the unfractionated and low-molecular-weight heparins available worldwide are produced by Chinese companies from porcine mucosa. China is the world's largest producer of pork and thus has plenty of raw material to produce heparins. However, the deadly African Swine Fever (ASF) outbreaks afflicting China since August 2018 may cause extensive losses to the pig herd, with serious consequences for the global supply of heparins. In 2008, a sudden shortage of heparin's raw material resulting from a viral disease in Chinese pigs prompted adulterations responsible for 80 deaths and hundreds of adverse events. This incident revealed the fragility of such a supply chain, which is mostly based on raw material from a single animal from a single country. A worldwide introduction of bovine mucosa heparins manufactured in different countries certainly is a feasible way to mitigate eventual shortages of these life-saving anticoagulants caused by local veterinary problems such as the ASF threatening China now.

Bovine Mucosal Heparins Are Comparable to Porcine Mucosal Heparin at USP Potency Adjusted Levels

Introduction: Bovine mucosal heparins (BMH) are currently being developed for re-introduction for both medical and surgical indications. BMH active pharmaceutical ingredient (API) exhibits a somewhat weaker USP potency when compared to PMHs. We hypothesized that when dosages are normalized based on the USP reference heparin, BMH will exhibit comparable in vitro and in vivo effects to those produced by PMH. Therefore, studies were developed to compare the APIs of bovine and porcine heparin.

Materials and Methods: API versions of PMH were obtained from Celsus Laboratories (Franklin, OH) and Medefil (Glen Ellen, IL). API versions of BMH were obtained from Kin Master (Passo Fundo, Brazil). Each of these heparins was assayed for their molecular weight profile, AT affinity, USP potency, and anticoagulant/antiprotease profiles using standard laboratory methods. In vitro protamine neutralization studies were carried out. Antithrombotic and hemorrhagic effects were measured in rats and pharmacodynamic profiles were assessed in primates.

Results: Size exclusion chromatography demonstrated that the mean molecular weight of BMH was ~15% higher than that of PMH (BMH: 20.1 ± 0.8 kDa and PMH: 17.5 ± 0.7 kDa). BMH exhibited an anti-Xa potency of 130 U/mg while PMH had an anti-Xa potency of 185 U/mg. In the anticoagulant and antiprotease assays, the BMH exhibited lower functionality which was proportional to USP potency. When the BMH was compared with PMH at potency adjusted concentrations, it showed identical concentration-response curves in the aPTT and anti-protease assays. However, in the protamine neutralization studies, BMH required slightly higher amounts of protamine in contrast to PMH. BMH and PMH administered to rats at equivalent anti-Xa unit dosages resulted in comparable antithrombotic activity and prolongation of bleeding time. Similar pharmacodynamic profiles were observed in primates when BMH and PMH were dosed on an anti-Xa U/kg basis.

Conclusion: BMH, when used at comparable anti-Xa unit levels, is comparable to PMH, however, it requires proportionally higher amount of protamine due to the increased mass for adjusting to higher potency. Additional studies on the structural characterization, interactions with PF4 and in vivo neutralization studies are ongoing.

Recombinant Heparin-New Opportunities

Heparin and heparan sulfate (HS) are polydisperse mixtures of polysaccharide chains between 5 and 50 kDa. Sulfate modifications to discreet regions along the chains form protein binding sites involved in cell signaling cascades and other important cellular physiological and pathophysiological functions. Specific protein affinities of the chains vary among different tissues and are determined by the arrangements of sulfated residues in discreet regions along the chains which in turn appear to be determined by the expression levels of particular enzymes in the biosynthetic pathway. Although not all the rules governing synthesis and modification are known, analytical procedures have been developed to determine composition, and all of the biosynthetic enzymes have been identified and cloned. Thus, through cell engineering, it is now possible to direct cellular synthesis of heparin and HS to particular compositions and therefore particular functional characteristics. For example, directing heparin producing cells to reduce the level of a particular type of polysaccharide modification may reduce the risk of heparin induced thrombocytopenia (HIT) without reducing the potency of anticoagulation. Similarly, HS has been linked to several biological areas including wound healing, cancer and lipid metabolism among others. Presumably, these roles involve specific HS compositions that could be produced by engineering cells. Providing HS reagents with a range of identified compositions should help accelerate this research and lead to new clinical applications for specific HS compositions. Here I review progress in engineering CHO cells to produce heparin and HS with compositions directed to improved properties and advancing medical research.

Combining NMR Spectroscopy and Chemometrics to Monitor Structural Features of Crude Hep-arin

Because of the complexity and global nature of the heparin supply chain, the control of heparin quality during manufacturing steps is essential to ensure the safety of the final active pharmaceutical ingredient (API). For this reason, there is a need to develop consistent analytical methods able to assess the quality of heparin early in production (i.e., as the crude heparin before it is purified to API under cGMP conditions). Although a number of analytical techniques have been applied to characterize heparin APIs, few of them have been applied for crude heparin structure and composition analyses. Here, to address this issue, NMR spectroscopy and chemometrics were applied to characterize 88 crude heparin samples. The samples were also analyzed by strong anion exchange HPLC (SAX-HPLC) as an orthogonal check of the purity levels of the crudes analyzed by NMR. The HPLC data showed that the chemometric analysis of the NMR data differentiated the samples based on their purity. These orthogonal approaches differentiated samples according their glycosaminoglycan (GAG) composition and their mono and disaccharide composition and structure for each GAG family (e.g., heparin/heparan, dermatan sulfate, and chondroitin sulfate A). Moreover, quantitative HSQC and multivariate analysis (PCA) were used to distinguish between crude heparin of different animal and tissue sources.

Structural and haemostatic features of pharmaceutical heparins from different animal sources: challenges to define thresholds separating distinct drugs

Heparins extracted from different animal sources have been conventionally considered effective anticoagulant and antithrombotic agents despite of their pharmacological dissimilarities. We performed herein a systematic analysis on the physicochemical properties, disaccharide composition, in vitro anticoagulant potency and in vivo antithrombotic and bleeding effects of several batches of pharmaceutical grade heparins obtained from porcine intestine, bovine intestine and bovine lung. Each of these three heparin types unambiguously presented differences in their chemical structures, physicochemical properties and/or haemostatic effects. We also prepared derivatives of these heparins with similar molecular weight differing exclusively in their disaccharide composition. The derivatives from porcine intestinal and bovine lung heparins were structurally more similar with each other and hence presented close anticoagulant activities whereas the derivative from bovine intestinal heparin had a higher proportion of 6-desulfated α-glucosamine units and about half anticoagulant activity. Our findings reasonably indicate that pharmaceutical preparations of heparin from different animal sources constitute distinct drugs, thus requiring specific regulatory rules and therapeutic evaluations.

Pharmacology of Heparin and Related Drugs

Heparin has been recognized as a valuable anticoagulant and antithrombotic for several decades and is still widely used in clinical practice for a variety of indications. The anticoagulant activity of heparin is mainly attributable to the action of a specific pentasaccharide sequence that acts in concert with antithrombin, a plasma coagulation factor inhibitor. This observation has led to the development of synthetic heparin mimetics for clinical use. However, it is increasingly recognized that heparin has many other pharmacological properties, including but not limited to antiviral, anti-inflammatory, and antimetastatic actions. Many of these activities are independent of its anticoagulant activity, although the mechanisms of these other activities are currently less well defined. Nonetheless, heparin is being exploited for clinical uses beyond anticoagulation and developed for a wide range of clinical disorders. This article provides a "state of the art" review of our current understanding of the pharmacology of heparin and related drugs and an overview of the status of development of such drugs.

Analysis of Heparins Derived From Bovine Tissues and Comparison to Porcine Intestinal Heparins

Heparin is a widely used clinical anticoagulant. It is also a linear glycosaminoglycan with an average mass between 10 and 20 kDa and is primarily made up of trisulfated disaccharides comprised of 1,4-linked iduronic acid and glucosamine residues containing some glucuronic acid residues. Heparin is biosynthesized in the Golgi of mast cells commonly found in the liver, intestines, and lungs. Pharmaceutical heparin currently used in the United States is primarily extracted from porcine intestines. Other sources of heparin including bovine intestine and bovine lung are being examined as potential substitutes for porcine intestinal heparin. These additional sources are intended to serve to diversify the heparin supply, making this lifesaving drug more secure. The current study examines bovine heparins prepared from both intestines and lung and compares these to porcine intestinal heparin. The structural properties of these heparins are examined using nuclear magnetic resonance, gel permeation chromatography, and disaccharide analysis of heparinase-catalyzed depolymerized heparin. The in vitro functional activities of these heparins have also been determined. The goal of this study is to establish the structural and functional similarities and potential differences between bovine and porcine heparins. Porcine and bovine heparins have structural and compositional similarities and differences.

[Enoxaparin is a low-molecular-weight heparin with a complex chemical structure and various non-anticoagulant properties]

The paper discusses the non-anticoagulant properties of unfractionated heparin and enoxaparin and their relation to their chemical structures. It is emphasized that enoxaparin has multiple, often interrelated, non-anticoagulant effects that can complement its antithrombotic activity and enhance the efficiency of therapy in patients receiving the drug for various indications. The realization of these effects requires the complex structure with the standard distribution of molecular weight (Mw) (average Mw, about 4500 Da, as well as Mw of less than 2000 Da (<20%), 2000 to 8000 Da (>68%), and more than 8000 Da (<18%), and with the standard content of 1.6-anhidro rings (15-25%), which is determined by the source of raw materials and by the production technology of the original drug and cannot be fully reproduced when designing its bioanalogues.

Stable isotopic analysis of porcine, bovine, and ovine heparins

The assessment of provenance of heparin is becoming a major concern for the pharmaceutical industry and its regulatory bodies. Batch-specific [carbon (δ(13) C), nitrogen (δ(15) N), oxygen (δ(18) O), sulfur (δ(34) S), and hydrogen (δD)] stable isotopic compositions of five different animal-derived heparins were performed. Measurements readily allowed their differentiation into groups and/or subgroups based on their isotopic provenance. Principle component analysis showed that a bivariate plot of δ(13) C and δ(18) O is the best single, bivariate plot that results in the maximum discrimination ability when only two stable isotopes are used to describe the variation in the data set. Stable isotopic analyses revealed that (1) stable isotope measurements on these highly sulfated polysaccharide (molecular weight ∼15 kDa) natural products ("biologics") were feasible; (2) in bivariate plots, the δ(13) C versus δ(18) O plot reveals a well-defined relationship for source differentiation of hogs raised in the United States from hogs raised in Europe and China; (3) the δD versus δ(18) O plot revealed the most well-defined relationship for source differentiation based on the hydrologic environmental isotopes of water (D/H and (18) O/(16) O); and (4) the δ(15) N versus δ(18) O and δ(34) S versus δ(18) O relationships are both very similar, possibly reflecting the food sources used by the different heparin producers.