Development, validation, and clinical pharmacokinetic application of ultra-performance liquid chromatography/tandem mass spectrometry method for simultaneously determining a novel recombinant hirudin derivative (Neorudin) and its active metabolite in human serum

Aptamer-thrombin loaded magnetic microspheres for bio-specific extraction and precise detection of hirudin

Hirudin, that is naturally occurring in leeches (Hirudo medicinalis) and known as the most potent natural inhibitor of thrombin, exerts double-edged effects in clinic application. It can be used as a therapeutic ingredient for cardiovascular disease, while it can be regarded as a toxic polypeptide with bleeding risk. Effective detection of hirudin in biological samples contributes greatly to reasonable therapy. In this study, we proposed a smart adsorbent based on affinity magnetic microspheres, where thrombin was immobilized for capturing hirudin in the animal serum. Aptamer was introduced as a ligand for linking the magnetic agarose microspheres and thrombin, thereby avoiding loss of biological activity of the enzyme to hirudin. Taken recombinant hirudin variant 2-Lys47 (rHV2) as a model, we established a rapid and bio-specific extraction method coupled with liquid chromatography and quadrupole-time-of-flight mass spectrometry (LC-QTOF/MS) for determination of hirudin in the serum. Owing to this strategy, a low limit of detection (LOD) of rHV2 (0.5 nM), a good linearity with correlation coefficient of 0.9975, an acceptable precision with relative standard deviation (RSD) below 3.6% (n = 6) and acceptable recoveries ranging from 85.7% to 90.2% were achieved. Moreover, the functionalized magnetic composite could be reused for at least nine cycles. Our work combined the merits of affinity separation and advanced instrument analysis for hirudin, providing a new vision to precise determination of hirudin in medical and pharmaceutical fields.

LC-MS/MS method for determination of r-RGD-hirudin in human plasma and its application in pharmacokinetic study

OBJECTIVE

This study aimed to develop a simple, sensitive, and selective Liquid chromatography with a Mass spectroscopic method for simultaneous quantification of a recombinant bifunctional hirudin (r-RGD-Hirudin, Bifunctional Hirudin, BFH) in human plasma and verify its effectiveness.

METHODS

The analytes and the internal standards from human plasma were extracted using the solid-phase extraction technique. The reconstituted samples were chromatographed on Waters C₁₈ column (BEH 50 × 2.1 mm, 1.7 μm) using a mixture of 0.1% formic acid/acetonitrile (85%/15%, v/v) with gradient elution as the initial mobile phase at a flow rate of 0.3 mL/min.

RESULTS

The effectiveness of the proposed method was verified over the concentration range of 10-2000 ng/mL for r-RGD-Hirudin. A linear calibration curve was obtained. The precision and accuracy of BFH in the intra- and inter-day runs fell within the range of ±15% at LQC, GMQC, MQC and HQC concentrations. The extraction recoveries and matrix effect at two quality control (QC) levels for BFH were confirmed to conform to the relevant requirement.

CONCLUSION

The proposed method was successfully adapted to examine the pharmacokinetics of BFH in 40 Chinese healthy volunteers, respectively.

A phase I, single and continuous dose administration study on the safety, tolerability, and pharmacokinetics of neorudin, a novel recombinant anticoagulant protein, in healthy subjects

The aim of this study was to evaluate the tolerability, safety, and pharmacokinetics of single and continuous dose administration of recombinant neorudin (EPR-hirudin, EH) by intravenous administration in healthy subjects, and to provide a safe dosage range for phase II clinical research. Forty-four subjects received EH as a single dose of between 0.2 and 2.0 mg/kg by intravenous bolus and drip infusion. In addition, 18 healthy subjects were randomly divided into three dose groups (0.15, 0.30, and 0.45 mg/kg/h) with 6 subjects in each group for the continuous administration trial. Single or continuous doses of neorudin were generally well tolerated by healthy adult subjects. There were no serious adverse events (SAEs), and all adverse events (AEs) were mild to moderate. Moreover, no subjects withdrew from the trial because of AEs. There were no clinically relevant changes in physical examination results, clinical chemistry, urinalysis, or vital signs. The incidence of adverse events was not significantly related to drug dose or systemic exposure. After single-dose and continuous administration, the serum EH concentration reached its peak at 5 min, and the exposure increased with the increase in the administered dose. The mean half-life (T_1/2 ), clearance (Cl), and apparent volume of distribution (Vd) of EH ranged from 1.7 to 2.5 h, 123.9 to 179.7 ml/h/kg, and 402.7 to 615.2 ml/kg, respectively. The demonstrated safety, tolerability, and pharmacokinetic characteristics of EH can be used to guide rational drug dosing and choose therapeutic regimens in subsequent clinical studies. Clinical trial registration: Chinadrugtrials.org identifier: CTR20160444.

Pharmacological Activities and Mechanisms of Hirudin and Its Derivatives - A Review

Hirudin, an acidic polypeptide secreted by the salivary glands of Hirudo medicinalis (also known as "Shuizhi" in traditional Chinese medicine), is the strongest natural specific inhibitor of thrombin found so far. Hirudin has been demonstrated to possess potent anti-thrombotic effect in previous studies. Recently, increasing researches have focused on the anti-thrombotic activity of the derivatives of hirudin, mainly because these derivatives have stronger antithrombotic activity and lower bleeding risk. Additionally, various bioactivities of hirudin have been reported as well, including wound repair effect, anti-fibrosis effect, effect on diabetic complications, anti-tumor effect, anti-hyperuricemia effect, effect on cerebral hemorrhage, and others. Therefore, by collecting and summarizing publications from the recent two decades, the pharmacological activities, pharmacokinetics, novel preparations and derivatives, as well as toxicity of hirudin were systematically reviewed in this paper. In addition, the clinical application, the underlying mechanisms of pharmacological effects, the dose-effect relationship, and the development potential in new drug research of hirudin were discussed on the purpose of providing new ideas for application of hirudin in treating related diseases.

Predicting the metabolic characteristics of neorudin, a novel anticoagulant fusion protein, in patients with deep vein thrombosis

INTRODUCTION

Recombinant neorudin (EPR-hirudin, EH) is an inactive prodrug that is converted to its active metabolite, hirudin variant 2-Lys47 (HV2), at the thrombus site. We aimed to investigate the mechanism underlying site-selective bioconversion of EH to HV2 at the thrombus target site and metabolic transformation of EH in patients with deep vein thrombosis (DVT).

MATERIALS AND METHODS

Metabolites in healthy volunteer plasma and urine after intravenous administration of EH were determined to elucidate how EH was metabolised after releasing HV2 at the target site in patients with DVT. After intravenous administration of EH in rats with venous thrombosis, the concentrations of EH in the blood and thrombus and the antithrombotic activity of EH were measured to predict whether EH could release HV2 at the thrombus site to exert anticoagulant effect in patients with DVT.

RESULTS

In healthy volunteers, EH and HV2 were predominantly excreted in the urine. Nine EH metabolites and ten HV2 metabolites truncated at the C-terminal were identified as N-terminal fragments, and these had the same cleavage sites. In rats with venous thrombosis, the area under the curve ratio of HV2 between the thrombus and blood was 29.5. The weight of wet thrombus was decreased with the production of HV2 by the cleavage of EH. The prothrombin time (PT) and prothrombin time (TT) changed proportionally to the concentration of EH and HV2 in the blood.

CONCLUSION

EH selectively accumulates and releases HV2 in the thrombus to exert antithrombotic effects, thus lowering the bleeding risk. Moreover, after conversion, EH may follow the same metabolic profile as that of HV2 in patients with DVT.

Evaluating prodrug characteristics of a novel anticoagulant fusion protein neorudin, a prodrug targeting release of hirudin variant 2-Lys47 at the thrombosis site, by means of in vitro pharmacokinetics

Recombinant neorudin (EPR-hirudin, EH), a low-bleeding anticoagulant fusion protein, is an inactive prodrug designed to be converted to the active metabolite, hirudin variant 2-Lys47 (HV2), locally at the thrombus site by FXa and/or FXIa, following activation of the coagulation system. Our aim was to evaluate the prodrug characteristics of EH by comparing the biotransformation of EH and HV2 in biological matrices, including rat blood, liver, and kidney homogenates, demonstrating the cleavage of EH to HV2 by FXa and FXIa, and comparing the conversion of EH to HV2 between fresh whole blood and whole-blood clot homogenate, using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS). Both EH and HV2 were stable in blood and unstable in the liver and kidney homogenates. Eight EH metabolites and eight HV2 metabolites identified as N-terminal fragments were found in the liver and kidney. C-terminal proteolysis is therefore the major metabolic pathway, with serine/cysteine carboxypeptidases and metallocarboxypeptidases being responsible for the degradation of EH and HV2 in the liver and kidney, respectively. EH was cleaved to release HV2 by FXIa. Higher levels of HV2 were produced from EH in the whole-blood clot homogenate, in which the coagulation system was activated compared with those in fresh whole blood. In conclusion, the metabolism of EH and HV2 shares the same cleavage pattern, and EH is transformed into HV2 when the coagulation system is activated, where FXIa is a specific enzyme. Our in vitro study revealed the anticipated prodrug characteristics of EH newly designed as an inactive prodrug of hirudin.