RGD-hirudin-based low molecular weight peptide prevents blood coagulation via subcutaneous injection

Thromboembolic disease is a common cardio-cerebral vascular disease that threatens human life and health. Thrombin not only affects the exogenous coagulation pathway, but also the endogenous pathway. Thus, it becomes one of the most important targets of anticoagulant drugs. RGD-hirudin is an anticoagulant drug targeting thrombin, but it can only be administered intravenously. We designed a low molecular weight peptide based on RGD-hirudin that could prevent blood clots. We first used NMR to identify the key amino acid residues of RGD-hirudin that interacted with thrombin. Then, we designed a novel direct thrombin inhibitor peptide (DTIP) based on the structure and function of RGD-hirudin using homology modeling. Molecular docking showed that the targeting and binding of DTIP with thrombin were similar to those of RGD-hirudin, suggesting DTIP interacted directly with thrombin. The active amino acids of DTIP were identified by alanine scanning, and mutants were successfully constructed. In blood clotting time tests in vitro, we found that aPTT, PT, and TT in the rat plasma added with DTIP were greatly prolonged than in that added with the mutants. Subcutaneous injection of DTIP in rats also could significantly prolong the clotting time. Thrombelastography analysis revealed that DTIP significantly delayed blood coagulation. Bio-layer interferometry study showed that there were no significant differences between DTIP and the mutants in thrombin affinity constants, suggesting that it might bind to other sites of thrombin rather than to its active center. Our results demonstrate that DTIP with low molecular weight can prevent thrombosis via subcutaneous injection.

A Heparin-Mimicking Block Copolymer Both Stabilizes and Increases the Activity of Fibroblast Growth Factor 2 (FGF2)

Fibroblast growth factor 2 (FGF2) is a protein involved in cellular functions in applications such as wound healing and tissue regeneration. Stabilization of this protein is important for its use as a therapeutic since the native protein is unstable during storage and delivery. Additionally, the ability to increase the activity of FGF2 is important for its application, particularly in chronic wound healing and the treatment of various ischemic conditions. Here we report a heparin mimicking block copolymer, poly(styrenesulfonate-co-poly(ethylene glycol) methyl ether methacrylate)-b-vinyl sulfonate) (p(SS-co-PEGMA)-b-VS, that contains a segment that enhances the stability of FGF2 and one that binds to the FGF2 receptor. The FGF2 conjugate retained activity after exposure to refrigeration (4 °C) and room temperature (23 °C) for 7 days, while unmodified FGF2 was inactive after these standard storage conditions. A cell study performed with a cell line lacking native heparan sulfate proteoglycans indicated that the conjugated block copolymer facilitated binding of FGF2 to its receptor similar to the addition of heparin to FGF2. A receptor-based enzyme-linked immunosorbant assay (ELISA) confirmed the results. The conjugate also increased the migration of endothelial cells by 80% compared to FGF2 alone. Additionally, the FGF2-p(SS-co-PEGMA)-b-VS stimulated endothelial cell sprouting 250% better than FGF2 at low concentration. These data verify that this rationally designed protein-block copolymer conjugate enhances receptor binding, cellular processes such as migration and tube-like formation, and stability, and suggest that it may be useful for applications in biomaterials, tissue regeneration, and wound healing.

Bridge-therapy with enoxaparin in the preoperative period of endarterectomy

Cervical clot is one of the complications of endarterectomy. This risk may be higher in patients using aspirin or clopidogrel. On the other hand, stroke may occur if the medication is interrupted before surgery. We carried out a prospective study of 124 endarterectomies in 119 patients in which aspirin or clopidogrel was stopped and a bridge-therapy with enoxaparin was administered preoperatively. There was no case of stroke during the period of the bridge-therapy. One patient developed cervical clot (0.8%) in the fifth postoperative day. Mortality rate in this series was 0.8%. There was no complication directly related to the use of enoxaparin. Bridge-therapy with low molecular weight heparin is a safe strategy for patients elected for endarterectomy.

Safety evaluation of enoxaparin in currently approved indications

BACKGROUND

Potential limitations of unfractionated heparin (UFH) have prompted a search for new antithrombin therapies in recent years. Enoxaparin has shown similar or improved efficacy when compared with UFH, but it has been associated with safety concerns of increased bleeding in patients with acute coronary syndromes in some studies.

OBJECTIVE

This narrative review focuses on the safety and tolerability of enoxaparin in adult patients in the setting of currently approved indications.

METHODS

Synthesis of evidence from recent trials, systematic reviews, meta-analyses, regulatory documents and clinical trials registries of manufacturers.

CONCLUSION

Enoxaparin can be considered for prophylaxis and treatment of a wide range of thrombotic conditions as an alternative to UFH with a clinically modest increase in bleeding complications, without altering the risk-benefit profile of this compound. Selection of the appropriate dosage is strongly recommended. Special precautions should be taken in specific populations that are at higher risk of bleeding, such as patients with renal dysfunction and elderly patients, where dose adjustment is recommended.

Fondaparinux: a pharmacoeconomic review of its use in the management of non-ST-segment elevation acute coronary syndrome

Fondaparinux (Arixtra) is an anticoagulant that selectively inhibits activated factor X, thereby interrupting the blood coagulation cascade. In OASIS-5, a large pivotal trial in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS), subcutaneous fondaparinux 2.5 mg once daily was noninferior to subcutaneous enoxaparin 1 mg/kg twice daily (both agents were administered over a mean of about 5 days in combination with antiplatelet therapy) in reducing death or ischaemic events at 9 days, and the efficacy was maintained for up to 6 months (study end). However, fondaparinux was associated with a significantly lower rate of bleeding than enoxaparin in the first 9 days, and at 3 and 6 months. This lower rate of bleeding led to lower long-term mortality and morbidity with fondaparinux than with enoxaparin. In modelled cost-utility analyses conducted from a healthcare payer perspective in Spain, France and the US with a lifetime horizon, fondaparinux once daily was predicted to be cost effective relative to enoxaparin twice daily with regard to the incremental cost per QALY gained. In Spain and the US, fondaparinux dominated enoxaparin (i.e. was less costly and more effective) and, in the French analysis, the incremental cost per QALY gained with fondaparinux versus enoxaparin was well within recommended thresholds. Results of short-term (6-month) cost analyses in the US and France also favoured fondaparinux over enoxaparin. Sensitivity analyses demonstrated that base-case conclusions were robust over a range of parameter estimates and assumptions, including plausible variations in baseline risk of a cardiac event or baseline risk of bleeding. In conclusion, in patients with NSTE-ACS receiving antiplatelet therapy, fondaparinux was cost effective relative to enoxaparin in cost-utility analyses in Europe and the US. This cost advantage primarily reflects the lower rate of bleeding with fondaparinux than with enoxaparin and the lower rate of mortality and morbidity over the long term.

A comparison of the biological activity of 2 formulations of enoxaparin in 12 healthy volunteers

INTRODUCTION

India is one of the few countries where biosimilar enoxaparin is available for clinical use. Despite availability since past 4 to 5 years, there is a paucity of published literature regarding their biological activity. The aim of the current study is to compare the biological activity of an endogenously developed formulation of enoxaparin with the branded formulation.

MATERIALS AND METHODS

Twelve healthy male volunteers received 1 subcutaneous injection of 2 different formulations of enoxaparin in a randomized, open-label, balanced, 2-treatment, 2-period, 2-sequence, cross-over study. The test formulation was Injection Troynoxa (enoxaparin sodium 40 mg/0.4 mL, Troikaa Pharmaceuticals Ltd., India) and reference formulation was Injection Clexane (enoxaparin sodium 40 mg/ 0.4 mL, Sanofi-Aventis, UK). The plasma anti-Xa activity and activated partial thromboplastin time (aPTT) were estimated on fully automated coagulometer predose and at 2, 4, 6, 8, and 10 hours following dosing with 40 mg/0.4 mL of enoxaparin.

RESULTS

The results of mixed model analysis of repeated measures analysis of variance (ANOVA) for estimating difference between least square means of test and reference formulations, at all time points, showed no significant differences in anti-Xa activity and plasma aPTT levels. Both formulations were well tolerated and there were no bleeding episodes.

CONCLUSION

After a single-dose injection in healthy participants, anti-Xa activities of 2 formulations of LMWH enoxaparin were comparable. No significant difference was observed in the mean plasma aPTT. It remains to be seen whether the 2 formulations would show comparable clinical efficacy.

Spotlight on enoxaparin in ST-segment elevation myocardial infarction

Enoxaparin (enoxaparin sodium; Lovenox) is a low-molecular-weight heparin (LMWH) that has recently been approved by the US FDA for use in patients with medically managed ST-segment myocardial infarction (STEMI), or STEMI with subsequent percutaneous coronary intervention. It binds to and potentiates the action of antithrombin, and inhibits coagulation factors XIa, IXa, Xa, and IIa (thrombin), thereby preventing formation of blood clots. Unfractionated heparin (UFH) has long been regarded as the antithrombotic agent of choice in the adjunctive treatment of patients with STEMI. However, compared with UFH, enoxaparin has many advantages in terms of its pharmacodynamic profile and, potentially, also its efficacy. Enoxaparin was significantly more effective than UFH in patients presenting with STEMI who underwent fibrinolytic therapy in terms of the 30-day combined incidence of all-cause mortality plus recurrent nonfatal myocardial infarction (MI) [primary endpoint], and all-cause mortality plus recurrent nonfatal MI plus urgent revascularization (secondary endpoint) in the ExTRACT-TIMI 25 trial. The significant difference in the incidence of the composite primary endpoint between these two groups was maintained at the 1-year follow-up. Although bleeding was reported more frequently with enoxaparin than with UFH in the ExTRACT-TIMI 25 trial, enoxaparin was associated with a net clinical benefit relative to UFH. Patients in this trial received enoxaparin as an initial 30 mg intravenous bolus, followed by 1 mg/kg subcutaneously within 15 minutes and then every 12 hours for up to 8 days; the first two subcutaneous dosages were not to exceed 100 mg. Patients > or =75 years of age did not receive the initial bolus of enoxaparin and the 12-hourly dosages were reduced to 0.75 mg/kg; the dose was also reduced to 1 mg/kg every 24 hours in patients of any age who had an estimated creatinine clearance of <30 mL/min. Data from several earlier randomized, multicentre, phase III trials support these results.