Differentiation of the low-molecular-weight heparins

Analysis of sulfates on low molecular weight heparin using mass spectrometry: structural characterization of enoxaparin

INTRODUCTION

Structural characterization of low molecular weight heparin (LMWH) is critical to meet biosimilarity standards. In this context, the review focuses on structural analysis of labile sulfates attached to the side-groups of LMWH using mass spectrometry. A comprehensive review of this topic will help readers to identify key strategies for tackling the problem related to sulfate loss. At the same time, various mass spectrometry techniques are presented to facilitate compositional analysis of LMWH, mainly enoxaparin. Areas covered: This review summarizes findings on mass spectrometry application for LMWH, including modulation of sulfates, using enzymology and sample preparation approaches. Furthermore, popular open-source software packages for automated spectral data interpretation are also discussed. Successful use of LC/MS can decipher structural composition for LMWH and help evaluate their sameness or biosimilarity with the innovator molecule. Overall, the literature has been searched using PubMed by typing various search queries such as 'enoxaparin', 'mass spectrometry', 'low molecular weight heparin', 'structural characterization', etc. Expert commentary: This section highlights clinically relevant areas that need improvement to achieve satisfactory commercialization of LMWHs. It also primarily emphasizes the advancements in instrumentation related to mass spectrometry, and discusses building automated software for data interpretation and analysis.

Preparation of low molecular weight heparins from bovine and ovine heparins using nitrous acid degradation

Low molecular weight heparins (LMWHs) are important anticoagulant drugs. Nitrous acid degradation is a major approach to produce LMWHs, such as dalteparin. Due to the foreseeable shortage of porcine intestinal mucosa heparin and other potential risks, expansion of other animal tissues for heparin preparation is necessary. Heparins from different tissues differ in structure and bioactivity potency, and these variations may be carried over to the LMWH products. Sophisticated analytical techniques have been applied to compare various versions of dalteparins produced from porcine intestinal, bovine lung and ovine intestinal heparins to elucidate the effects of different animal tissues starting materials and processing conditions on the properties of final dalteparin products. With adjusted depolymerization conditions, versions of dalteparins that qualify under the European Pharmacopeia (EP) specifications were manufactured using non-porcine heparins. Dissimilarities among the three interspecies animal tissue heparin-derived dalteparins regarding fine structures are also disclosed, and their origins are discussed.

An engineered platform based on chitin-affinity immobilization for producing low molecular weight heparin

Using chitin-affinity interaction between triple-functional heparinase I (Hep I) and chitin, an engineered platform was prepared to produce controllable low molecular weight heparin (LMWH). Chitin microspheres with well-defined nanofibrils were fabricated through a "bottom up" pathway. An enhanced soluble protein, ChBD-SUMO-Hep I (CSH-I), was expressed in 3L batch fermentation with a high bioactivity of 2.5×10³ IU/L. Chitin binding domain (ChBD) can specifically bind to chitin in noncovalent way, which leads to the immobilization and purification of enzyme in a single step. The immobilized CSH-I was preferred over its free counterpart due to its higher tolerance to heat and pH, as well as improved shelf-life. The restraint enzyme could be reused up to 8 times to achieve a conversion yield exceeding 90%. By using the bioinspired conjugates, the qualified LMWH fractions were obtained by monitoring the degradation process with an absorbance range of 44.5-68.3 at 232nm.

Low-Molecular-Weight Heparin Therapy for Patients Undergoing Total Knee Replacement Surgery: Cost and Outcomes

Objective:

In March 1997, a community hospital system changed the low-molecular-weight heparin (LMWH) product on formulary from enoxaparin to dalteparin through a therapeutic interchange for all uses except patients undergoing total knee replacement (TKR) surgery. In October 1997, therapeutic interchange of LMWHs (enoxaparin to dalteparin) was instituted for patients undergoing TKR surgery. The cost equivalence of these therapies in TKR surgery was evaluated.

Methods:

A cohort of patients admitted to three health-system facilities who underwent primary TKR surgery between July 1, 1996 and December 31, 1998 was assembled retrospectively. Costs and outcomes associated with a formulary interchange for LMWH products (from enoxaparin to dalteparin) initiated in October 1997 for TKR surgery were analyzed using data abstracted hospital records and decision support systems. To evaluate equivalence between the drugs, the difference in median inpatient health care costs (with 95% confidence intervals [CIs]) was calculated. Equivalence of outcomes (eg, adverse events) in terms of risk ratios was also evaluated.

Results:

Inpatient costs were essentially equivalent for patients treated with enoxaparin (n = 88) and dalteparin (n = 101), with a slightly higher median cost among enoxaparin-treated patients ($172 [95% CI, -$17 to + $395]). CIs for the crude and regression-adjusted findings included the possibility of no cost difference (ie, $0). The median time to hospital discharge was identical, at 6 days. Outcomes were otherwise similar between the two groups.

Conclusions:

Our therapeutic interchange program was successful. Inpatient costs were equivalent when patients were treated with either enoxaparin or dalteparin for TKR surgery.

Non-anticoagulant effects of low molecular weight heparins in inflammatory disorders: A review

Low molecular weight heparins (LMWHs) are produced by chemical or enzymatic depolymerization of unfractionated heparin (UFH). Besides their well-known anticoagulant effects, LMWHs have also been reported to exhibit numerous anti-inflammatory properties. Previous studies have, however, shown that different production processes result in unique structural characteristics of LMWHs. The structural variations may help explain the different therapeutic spectrums in disease treatment for non-anticoagulant effects. In the present review, we summarize major advances in understanding and exploiting the anti-inflammatory disorder activities of LMWHs, based on mechanistic studies, preclinical experiments and clinical trials. We highlight differences in these activities of commercially available LMWHs produced using different manufacturing processes. We stress the importance of structure-activity relationship (SAR) studies on the non-anticoagulant effects of LMWHs and discuss strategies for exploring new clinical indications.

Effect of Low Molecular Weight Heparins (LMWHs) on antiphospholipid Antibodies (aPL)-mediated inhibition of endometrial angiogenesis

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by vascular thrombosis and/or pregnancy morbidity in the presence of circulating antiphospholipid antibodies (aPL). Different pathogenic mechanisms for aPL-mediated pregnancy failure have been proposed. In particular a direct effect of aPL on both maternal and fetal side of the placental tissue has been reported, since their reactivity with β2-glycoprotein I (β2GPI) makes them adhere to trophoblast and human endometrial endothelial cell (HEEC) membranes. β2GPI can be recognized by aPL that, once bound, interfere with both trophoblast functions and with the HEEC differentiation.APS patients can be successfully treated with Low Molecular Weight Heparin (LMWH). Recent reports suggest that LMWH acts through mechanisms alternative to its well known anticoagulant effect, because of its ability to bind β2GPI. In our previous studies, we showed that LMWH is able to reduce the aPL binding to trophoblasts and restore cell invasiveness and differentiation. So far, however, no study has described its effects on endometrial angiogenesis.The aim of our research was to evaluate whether two LMWHs, tinzaparin and enoxaparin, have an effect on the aPL-inhibited endometrial angiogenesis. This prompted us to investigate: (i) in vitro HEEC angiogenesis through a Matrigel assay; (ii) VEGF secretion by ELISA; (iii) matrix metalloproteinase-2 (MMP-2) activity by gelatin zymography; (iv) Nuclear Factor-κB (NF-κB) DNA binding activity by colorimetric assay; (v) STAT-3 activation by a sandwich-ELISA kit. Furthermore, using an in vivo murine model we investigated the LMWHs effects on angiogenesis.We demonstrated that the addition of LMWHs prevents aPL-inhibited HEEC angiogenesis, both in vitro and in vivo, and is able to restore the aPL inhibited NF-κB and/or STAT-3 activity, the VEGF secretion and the MMPs activity.The demonstration of a beneficial role for LMWHs on the aPL-inhibited HEEC angiogenesis might provide additional mechanisms whereby this treatment protects early pregnancy in APS.

Linear polyalkylamines as fingerprinting agents in capillary electrophoresis of low-molecular-weight heparins and glycosaminoglycans

Glycosaminoglycan (GAG) analysis represents a challenging frontier despite the advent of many high-resolution technologies because of their unparalleled structural complexity. We previously developed a resolving agent-aided capillary electrophoretic approach for fingerprinting low-molecular-weight heparins (LMWHs) to profile their microscopic differences and assess batch-to-batch variability. In this report, we study the application of this approach for fingerprinting other GAGs and analyze the basis for the fingerprints observed in CE. Although the resolving agents, linear polyalkylamines, could resolve the broad featureless electropherogram of LMWH into a large number of distinct, highly reproducible peaks, longer GAGs such as chondroitin sulfate, dermatan sulfate, and heparin responded in a highly individualistic manner. Full-length heparin interacted with linear polyalkylamines very strongly followed by dermatan sulfate, whereas chondroitin sulfate remained essentially unaffected. Oversulfated chondroitin sulfate could be easily identified from full-length heparin. Scatchard analysis of the binding profile of enoxaparin with three linear polyalkylamines displayed a biphasic binding profile suggesting two distinctly different types of interactions. Some LMWH chains were found to interact with linear polyalkylamines with affinities as high as 10 nM, whereas others displayed nearly 5000-fold weaker affinities. These observations provide fundamental insight into the basis for fingerprinting of LMWHs by linear polyalkylamine-based resolving agents, which could be utilized in the design of advanced resolving agents for compositional profiling, direct sequencing, and chemoinformatics studies.

Safety assessment and pharmacodynamics of a novel ultra low molecular weight heparin (RO-14) in healthy volunteers--a first-time-in-human single ascending dose study

INTRODUCTION

RO-14 is a novel ultra low molecular heparin. The purpose of this study was to evaluate the safety and pharmacodynamic profile of RO-14 in healthy males.

MATERIALS AND METHODS

We conducted a two-stage, single-center, open-label, randomized study. Two cohorts of 6 volunteers were randomly assigned to 12 single, ascending subcutaneous doses (1750-19950IU of anti-FXa activity) in an alternating crossover fashion. Safety was assessed by spontaneous/elicited adverse events, medical examination and laboratory tests. Anti-FXa activity and anti-FIIa activity were assessed throughout the 24hours after dosing. Dose proportionality and linearity of the anti-FXa activity were evaluated.

RESULTS

All doses were well tolerated and there were no bleeding events. At the lowest dose, anti-FXa activity A(max) was 0.16 (±0.02) IU/mL and AUC(0-24) was 1.11 (±0.24) IU*h/mL, At the highest dose anti-FXa activity A(max) was 1.67 (±0.15) IU/mL; AUC(0-24) was 21.48 (±4.46) IU*h/mL and t½ was 8.05h. Mean T(max) (all doses) was 2.86 (±0.39) h. RO-14 showed proportional and linear pharmacodynamics [normalized A(max) among doses (p=0.594) and normalized AUC(0-24) (p=0.092), correlations between A(max-)dose (R(2)=0.89, p<0.001) and AUC(0-24)-dose (R(2)=0.86, p<0.001)]. Anti-FIIa activity was below the detection limit (0.1IU/ml) at all dose levels. No clinically significant changes were observed in the platelet count, APTT, PT, TT, fibrinogen and antithrombin.

CONCLUSIONS

In this phase I study, RO-14 exhibited a good safety profile, anti-FXa activity for either prophylaxis or treatment of venous thromboembolism, linear pharmacodynamics, a longer elimination half-life than currently marketed low molecular weight heparin and no anti-FIIa activity.

New and Generic Anticoagulants and Biosimilars: Safety Considerations

The recent health care changes and approval of a generic low-molecular-weight heparin (LMWH) by the US Food and Drug Administration (FDA) merit a review of the facts regarding the new and generic anticoagulants. Fatal hypotension from anaphylactoid type reactions following heparin administration was responsible for more than 149 deaths all over the world. Researchers detected a heparin-like semisynthetic contaminant, over-sulfated chondroitin sulfate (OSCS), that appeared to be intentional. Low-molecular-weight heparins are produced using unfractionated heparin and OSCS has been found in various batches of LMWHs. Some newer anticoagulants are claiming to be free from the need to monitor for therapeutic effect and bleeding risk. Therefore, monitoring assays are not being developed and there is no antidote to reverse bleeding. In addition, there are concerns about reproducibility, product variation, and quality. In conclusion, although the generic LMWHs and newer anticoagulants may appear to be effective for qualified indications, their safety remains to be a concern.

Low-molecular-weight heparins in the treatment of cancer-associated thrombosis: a new standard of care?

Cancer patients are twice as likely to develop postoperative venous thromboembolism (VTE) than non-cancer patients undergoing the same surgical procedure. Causes of cancer-associated thrombosis include: the capacity of tumor cells and their products to interact with platelets, clotting, and fibrinolytic proteins. Aggressive antitumor therapy with agents such as platinum compounds, high-dose fluorouracil, mitomycin-C, tamoxifen, and growth factors increase the risk of cancer-associated thrombosis. Despite the high risk of VTE in patients with cancer, thromboprophylaxis in surgical and medical oncology patients is low. Initial therapy of VTE in patients with cancer is low-molecular-weight heparin (LMWH) or unfractionated heparin. Long-term secondary prophylaxis of VTE is generally accomplished with oral anticoagulants, primarily warfarin. Evidence supports the use of LMWH for prevention and treatment of cancer-associated thrombosis because it is more easily administered, does not require laboratory monitoring, has a lower risk of adverse events, and is more cost effective than unfractionated heparin. In addition, the antineoplastic effects of LMWH have been demonstrated, including direct antitumor, antiangiogenic, and immune system modulatory action. Each LMWH is a unique biological entity having product-specific molecular and structural attributes; therefore, different LMWHs cannot be given interchangeably. Continued investigation of LMWH therapy in patients with cancer is warranted.

Factors that influence prescribing within a therapeutic drug class

RATIONALE, AIMS AND OBJECTIVES

The decision to prescribe one drug instead of another within the same therapeutic class may be influenced by a variety of drug-related, direct, or indirect factors; but little is known about which considerations are most important in such choices. The low-molecular-weight heparins (LMWHs) represent a class of drugs that are commonly used and for which therapeutic equivalence has been debated in the literature. The purpose of this study was to identify and compare factors perceived by doctors and clinical pharmacists to be influential in prescribing decisions among LMWHs.

METHODS

Doctors and clinical pharmacists were interviewed to elicit information and to rank factors that influence the prescribing and use of LMWHs in community hospitals in the United States. For each factor, the mean and median of the rating were determined along with the frequency distribution across ratings. The non-parametric Mann-Whitney U-test was used to examine differences between doctors and clinical pharmacists.

RESULTS

Both groups considered efficacy, formulary status, and policies restricting drug use to be highly influential in the decision to use one LMWH instead of another. Compared to clinical pharmacists, doctors rated personal experience as more influential, whereas they rated drug cost and prescribing guidelines lower.

CONCLUSIONS

These findings suggest that doctors and clinical pharmacists differentiate between LMWHs based on differences between products and because of hospital administrative programs (such as drug formularies). This information may be of value in designing programs to alter medication use.

Therapeutic equivalency of low-molecular-weight heparins

OBJECTIVE

To review the recent literature on the approved uses of enoxaparin, dalteparin, ardeparin, and tinzaparin and the evidence for therapeutic equivalence.

DATA SOURCES

A MEDLINE search (1993-January 2001) was conducted to identify English-language literature available on enoxaparin, dalteparin, ardeparin, and tinzaparin.

STUDY SELECTION

All controlled trials evaluating low-molecular-weight heparins (LMWHs) versus standard therapy powered to detect a significant difference were reviewed.

DATA EXTRACTION

Agents were reviewed with regard to safety and efficacy.

DATA SYNTHESIS

As a class, LMWHs have chemical, physical, and clinical similarities. LMWHs have greater bioavailability, longer half-lives, a more predictable pharmacologic response, possible improved safety, and similar or greater efficacy compared with unfractionated heparin (UFH). Because of this, enoxaparin, dalteparin, ardeparin, and tinzaparin are being considered as alternatives to UFH or warfarin, and there is potential for therapeutic interchange. Evaluation of clinical trials is limited because of differing diagnostic methods, drug administration times, dose equivalencies, and outcome measurements.

CONCLUSIONS

Only 1 trial has evaluated 2 LMWHs in a direct comparison in the same study. There is insufficient evidence for determining the therapeutic equivalence of LMWHs.