Anticoagulant Activity of Hirulog™, a Direct Thrombin Inhibitor, in Humans

1993 ◽  
Vol 69 (02) ◽  
pp. 157-163 ◽  
Author(s):  
Irving Fox ◽  
Adrian Dawson ◽  
Peter Loynds ◽  
Jane Eisner ◽  
Kathleen Findlen ◽  
...  
Keyword(s):  
Rational Design ◽  
Therapeutic Potential ◽  
Anticoagulant Activity ◽  
Subcutaneous Administration ◽  
Direct Thrombin Inhibitor ◽  
Controlled Study ◽  
Thrombin Inhibitor ◽  
Thrombin Time ◽  
Thrombotic Disease ◽  
Dose Dependent

SummaryHirulog™ (BG8967) is a direct thrombin inhibitor built by rational design using the protein hirudin as a model (Maraganore et al. [1990]; Biochemistry 29: 7095–101). In order to evaluate the therapeutic potential for hirulog in the management of thrombotic disease, the tolerability and anticoagulant activity of the agent were examined in a study of human volunteers.In a randomized, placebo-controlled study (n = 54), the intravenous infusion of hirulog over 15 min showed a rapid, dose-dependent prolongation of activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). There was a corresponding dose-dependent increase in plasma hirulog levels. The peptide was rapidly cleared with a half-life of 36 min and a total body clearance rate for the peptide of 0.43 1 kg−1 h−1. Similar activity was observed following subcutaneous injection but with sustained pharmacodynamic and pharmacokinetic behavior. There was a significant correlation between pharmacokinetic and pharmacodynamic variables for both intravenous (r = 0.8, p <0.001) and subcutaneous administration (r = 0.7, p = 0.002).To evaluate the possible interactions of aspirin on the tolerability and anticoagulant activity of intravenous hirulog, a cross-over design was employed in eight subjects. Aspirin administration did not modify the peptide’s activity. At the administered dose of 0.6 mg kg−1 h−1 for 2 h, hirulog infusion prolonged APTT from 230 to 260% baseline. The infusion of hirulog in subjects who had received aspirin was not associated with any significant changes in the template bleeding time.The final phase of the study examined the activity and tolerability of hirulog in ten subjects during prolonged intravenous infusions for up to 24 h. The peptide (0.3 mg kg−1 h−1) exhibited sustained anticoagulant activity with no evidence for a cumulative effect. During hirulog infusion, APTT was prolonged from 210 to 250% baseline.In all phases of the study, hirulog administration was generally well-tolerated.Our observations show that hirulog is an active antithrombin agent with excellent tolerability in humans. As a direct thrombin inhibitor, hirulog provides a novel approach for the management of thrombotic disease.

Pharmacokinetics (PK) and Pharmacodynamics (PD) of a New Direct Thrombin Inhibitor (DPOC-4088) After Single Oral Doses of Two Prolonged Release Formulations in Healthy Male Subjects,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3351-3351
Author(s):  
Luc M Van Bortel ◽  
Griet Van Lancker ◽  
Henri Vanden Bavière ◽  
Willem Hettema ◽  
Edwin Spaans ◽  
...  
Keyword(s):  
Venous Thromboembolism ◽  
Plasma Concentrations ◽  
Cervical Lymphadenopathy ◽  
Direct Thrombin Inhibitor ◽  
Thrombin Inhibitor ◽  
Prolonged Release ◽  
Thrombin Time ◽  
Healthy Male ◽  
Thrombin Inhibition ◽  
Oral Doses

Abstract Abstract 3351 Background: DPOC-4088 is an orally active, potent, rapidly binding, reversible direct thrombin inhibitor (DTI) being developed as a once-a-day alternative to warfarin for primary prevention of venous thromboembolism. Objectives: This Phase I study was designed to: (1) compare plasma concentration-ratios (Cmax/C12 hr and Cmax/C24 hr) and other standard PK parameters (Tmax, AUC0-∞, T1/2 terminal) following single oral dosing with 100 mg and 200 mg DPOC-4088 tablets in two prolonged release formulations (16 and 20 hr); (2) determine the extent of thrombin inhibition of these formulations as measured by activated partial thromboplastin time [aPTT], ecarin clotting time [ECT], thrombin time [TT] and prothrombin time [PT] (reported as the international normalized ratio [INR]); and (3) assess the safety of DPOC-4088 in healthy male volunteers. Methods: Randomized, open-label, 4-period crossover design. Subjects were dosed in 4 periods after an overnight fast and had blood drawn for PK/PD determinations immediately prior to dosing and at specified time intervals for 48 hrs post-dosing. Each dosing period was separated by a ≥5-day washout. Results: Twelve subjects aged 21 to 45 (mean 32.9 ± 8.55) years were enrolled and completed all 4 dosing periods. Increases in Cmax and AUC were dose proportional for both formulations, with the 20 hr-release formulation exhibiting slightly lower Cmax, and Cmax/C12 hr and Cmax/C24 hr ratios for a given dose compared to the 16 hr formulation (Table). Median tmax was 3–4 hrs. Geometric means of T1/2 terminal ranged from 4.0 to 5.8 hrs. Compared to pre-dose values, increases in all PD clotting parameters (aPTT, ECT, TT, and INR) closely followed the shape of the PK profile, were dose-dependent, and exhibited no lag time in response, suggesting a direct effect of DPOC-4088. Changes in aPTT, ECT, TT, and INR were correlated with peak DPOC-4088 concentrations. At 24 hrs post-dose, mean aPTT remained 12–15% above the pre-dose aPTT after 100 mg DPOC-4088 and 21–24% above pre-dose after 200 mg. The mean 24 hr ECT remained 21–23% and 35–36% above the pre-dose ECT for the 100 and 200 mg doses, respectively. Mean TT returned to within 1–15% of pre-dosing TT by 48 hrs. After single doses of 100 or 200 mg DPOC-4088, mean peak INRs were reached at 4 hrs for both the 100 mg (1.15–1.17) and 200 mg (1.28–1.30) formulations, returning to pre-dose INRs by 48 hrs. DPOC-4088 at both doses and release formulations was well-tolerated. Adverse events (AEs) occurred in 9/12 subjects; most were grade 1, unrelated or unlikely to be related to DPOC-4088, and resolved within hours without sequelae (headache, oropharyngeal pain, nausea, cervical lymphadenopathy, neck pain, fatigue). Among the AEs considered at least possibly related to DPOC-4088 administration, only grade 1 epistaxis (n=1) and blood in stools (n=1) were potentially linked to the PD activity of DPOC-4088. Conclusions: Following administration of single oral doses of DPOC-4088, a new once-daily DTI, dose proportionality was observed in the PK parameters for two prolonged release formulations. Evidence of anticoagulation efficacy by direct thrombin inhibition was reflected in key PD clotting parameters. The PD parameters were well-correlated with DPOC-4088 plasma concentrations and other PK parameters. At 100 and 200 mg doses, DPOC-4088 was safe and well-tolerated. Given the slightly lower Cmax/C24 hr and corresponding peak/trough PD ratios, the 20 hr release tablet is the preferred candidate formulation for further testing of DPOC-4088 in multiple-dose studies and for continued clinical development of DPOC-4088 for prevention of venous thromboembolism. PK/PD Parameters of Two Doses and Two Prolonged Release Formulations of DPOC-4088 Disclosures: Van Bortel: Diakron, GSK, JNJ, Merck, Menarini, Novartis, Nycomed, Recordati, Servier: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Hettema:Kinesis Pharma, BV: Employment. Spaans:Kinesis Pharma, BV: Employment. Ramakrishnan:Orchid Healthcare: Employment. Elumalai:Orchid Healthcare: Employment. Jayanthi:Orchid Healthcare: Employment. Allard:Diakron Pharmaceuticals: Employment.

Reversal of Dabigatran's Anticoagulant Activity in the Monkey by a Specific Antidote and Pharmacokinetic and Pharmacodynamic Modeling

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 22-22 ◽  
Author(s):  
Joshuaine Toth ◽  
Guanfa Gan ◽  
Joanne van Ryn ◽  
Holly Dursema ◽  
Jennifer Isler ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Anticoagulant Activity ◽  
Plasma Concentrations ◽  
Mass Action ◽  
Pharmacodynamic Modeling ◽  
Dependent Manner ◽  
Thrombin Time ◽  
Binding Interaction ◽  
Mass Action Kinetics ◽  
Dose Dependent

Abstract Abstract 22 Background: The objective of this study is to determine the pharmacokinetics (PK) and pharmacodynamics (PD) of dabigatran (a small molecule thrombin inhibitor) and its antidote (a humanized Fab against dabigatran) in the monkey and to develop a combined mechanistic mathematical model to describe the data. Methods: There were three groups: control, antidote alone and dabigatran etexilate (DE) + antidote. Rhesus monkeys (n = 2/group) received either 12 mg/kg/day of DE or vehicle orally on Days 1–4, 15–18 and 29–32 with a single IV dose of the antidote administered 90 minutes after DE on Days 4, 18 and 32. Doses of the antidote were 30, 90 or 175 mg/kg, respectively. PK parameters of the antidote and sum dabigatran (dabigatran plus its glucuronides) were determined after measurements of plasma concentrations. Coagulation activity was measured using a diluted thrombin time assay to determine the activity of the unbound sum dabigatran. Results: The PK of the antidote were not affected by dabigatran. Clearance of the antidote was low (0.87 mL/min/kg) and steady-state volume of distribution was small (0.06 L/kg), indicating that the antidote was mostly restricted to plasma. The plasma profile of the antidote was bi-phasic with a short initial phase t1/2 of 0.4 hour (h) and a terminal phase t1/2 of 4.3 h. Immediately after antidote dosing, plasma concentrations of sum dabigatran increased, a consequence of the rapid redistribution of dabigatran and its glucuronides from tissue to plasma due to binding to the antidote. Complete reversal of dabigatran's anticoagulant activity was observed immediately after antidote dosing at all three dose levels, as measured by the diluted thrombin time assay, which indicates that all dabigatran was bound to the antidote. The degree to which this reversal effect was maintained over an extended period (24 h) was dose-dependent. A mechanistic ordinary differential equation model, based on the mass action kinetics for describing the distribution, binding and elimination of dabigatran and its antidote, was developed by combining the PK models for dabigatran and the antidote and adding the binding interaction (1:1 stoichiometry) between the two compounds. The distribution and elimination parameters of the dabigatran-antidote complex were assumed to be the same as those of the antidote, based on similar measured PK parameters of the antidote with and without dabigatran in the monkey. The combined PK/PD model of dabigatran and antidote was able to describe the in vivo PK/PD data observed in monkeys. Conclusion: The dabigatran-specific antidote successfully reversed the anticoagulant activity of dabigatran in the monkey in a dose-dependent manner, and our combined mathematical model accurately describes monkey PK/PD data of sum dabigatran and its antidote. Insights gained from this model will be used to guide model development for clinical trials. Disclosures: Toth: Boehringer Ingelheim: Employment. Gan:Boehringer Ingelheim: Employment. van Ryn:Boehringer Ingelheim: Employment. Dursema:Boehringer Ingelheim: Employment. Isler:Boehringer Ingelheim: Employment. Coble:Boehringer Ingelheim: Employment. Burke:Boehringer Ingelheim: Employment. Lalovic:Boehringer Ingelheim: Employment. Olson:Boehringer Ingelheim: Employment.

Biochemical and pharmacological effects of the direct thrombin inhibitor AR-H067637

2009 ◽  
Vol 101 (06) ◽  
pp. 1051-1059 ◽  
Author(s):  
Christer Mattsson ◽  
Tord Inghardt ◽  
Margareta Elg ◽  
Johanna Deinum
Keyword(s):  
Competitive Inhibitor ◽  
Direct Thrombin Inhibitor ◽  
Anticoagulant Effect ◽  
Thrombin Inhibitor ◽  
Thrombin Time ◽  
Clotting Time ◽  
Binding Studies ◽  
Plasma Coagulation ◽  
Coagulation Assays

SummaryAZD0837 is in development as a new oral anticoagulant for use in thromboembolic disorders. In vivo, AZD0837 is converted to AR-H067637, a selective and reversible direct thrombin inhibitor. Established biochemical methods were used to assess and measure the biochemical and pharmacological properties of AR-H067637. Both direct Biacore binding studies of AR-H067637 with immobilised α-thrombin and inhibition studies using pre-steady state kinetics with thrombin in the fluid phase confirmed that AR-H067637 is a rapid-binding, reversible and potent (inhibition constant K i = 2–4 nM), competitive inhibitor of thrombin, as well as of thrombin bound to fibrin (clot-bound thrombin) or to thrombomodulin. The total amount of free thrombin generated in platelet-poor clotting plasma was inhibited concentration-dependently by AR-H067637, with a concentration giving half maximal inhibition (IC50) of 0.6 μM. Moreover, AR-H067637 is, with the exception of trypsin, a se-lective inhibitor for thrombin without inhibiting other serine proteases involved in haemostasis. Furthermore, no anticoagulant effect of the prodrug was found. AR-H067637 prolonged the clotting time concentration-dependently in a range of plasma coagulation assays including activated partial thromboplastin time, prothrombin time, prothrombinase-induced clotting time, thrombin time and ecarin clotting time. The two latter assays were found to be most sensitive for assessing the anticoagulant effect of AR-H067637 (plasma IC50 93 and 220 nM, respectively). AR-H067637 also inhibited thrombin-induced platelet activation (by glycoprotein IIb/IIIa exposure, IC50 8.4 nM) and aggregation (IC50 0.9 nM). In conclusion, AR-H067637 is a selective, reversible, competitive inhibitor of α-thrombin, with a predictable anticoagulant effect demonstrated in plasma coagulation assays.

Evaluation of a multifunctional staphylokinase variant with thrombin inhibition and antiplatelet aggregation activities produced from salt-inducible E. coli GJ1158

2013 ◽  
Vol 91 (10) ◽  
pp. 839-847 ◽  
Author(s):  
Anmol Kumar ◽  
Krishna Kanth Pulicherla ◽  
Candasamy Mayuren ◽  
Seetharam Kotra ◽  
Krothapalli Rajasurya Sambasiva Rao
Keyword(s):  
Therapeutic Potential ◽  
Expression System ◽  
Dependent Manner ◽  
Thrombin Time ◽  
Yeast Expression System ◽  
Treatment Groups ◽  
Thrombin Inhibition ◽  
Antiplatelet Aggregation ◽  
Economic Production ◽  
Dose Dependent

Reocclusion is one of the major root causes for secondary complications that arise during thrombolytic therapy. A multifunctional staphylokinase variant SRH (staphylokinase (SAK) linked with tripeptide RGD and didecapeptide Hirulog) with antiplatelet and antithrombin activities in addition to clot specific thrombolytic function, was developed to address the reocclusion problem. We preferred to use Escherichia coli GJ1158 as the host in this study for economic production of SRH by osmotic (0.3 mol/L sodium chloride) induction, to overcome the problems associated with the yeast expression system. The therapeutic potential of SRH was evaluated in the murine model of vascular thrombosis. The SAK protein (1 mg/kg body mass) and SRH protein (1 mg/kg and 2 mg/kg) were administered intravenously to the different treatment groups. The results have shown a dose-dependent antithrombotic effect in carrageenan-induced mouse tail thrombosis. The thrombin time, activated partial thromboplastin time, and prothrombin time were significantly prolonged (p < 0.05) in the SRH-infused groups. Moreover, SRH inhibited platelet aggregation in a dose-dependent manner (p < 0.05), while the bleeding time was significantly (p < 0.05) prolonged. All of these results inferred that the osmotically produced multifunctional fusion protein SRH (SAK–RGD–Hirulog) is a promising thrombolytic agent, and one which sustained its multifunctionality in the animal models.

scholarly journals Reversal of Trauma-Induced Bleeding and Anticoagulation with a Dabigatran-Specific Antidote (idarucizumab) As Assessed By Shed and Washed Blood Tests in a Pig Model of Supratherapeutic Anticoagulation and Trauma

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4268-4268
Author(s):  
Oliver Grottke ◽  
Markus Honickel ◽  
Johanna Schurer ◽  
Joanne van Ryn
Keyword(s):  
Blood Loss ◽  
Research Funding ◽  
Anticoagulant Activity ◽  
Alternative Methods ◽  
Thrombin Time ◽  
Wound Site ◽  
Shed Blood ◽  
Time Points ◽  
Superficial Wound ◽  
Dose Dependent

Abstract Background: The most frequent side effect associated with anticoagulant therapy is bleeding. Testing reversal strategies in patients is difficult due to the unpredictability, rarity and heterogeneity of these events. Currently methods to reverse this bleeding are being tested in a variety of clinical settings in volunteers by using reversal of anticoagulation as a marker of reversal of bleeding in patients. However, the limitation of volunteer studies is the lack of understanding between the assay being used to measure anticoagulation and if its reversal has any relevance for bleeding reversal in patients. A marker of bleeding that was safe to use in volunteers and also relevant for predicting reversal of bleeding in a patient would be advantageous. Objective: The feasibility of two markers of bleeding - fibrin formation (fibrinopeptide A, FPA) in blood as it exits a wound and blood loss measured via a washed blood method, both at a superficial wound site - were tested in pigs under high dabigatran anticoagulation. Reversal of dabigatran anticoagulation and bleeding following trauma injury were evaluated with idarucizumab and outcomes compared to the markers of bleeding from superficial wound. Methods: After ethical approval dabigatran etexilate (30 mg/kg p.o. twice daily, n=24) or placebo (n=6, no dabigatran anticoagulation) was administered to male pigs for 3 days. On Day 4, the pigs were anesthetized and given a 90 min infusion of active dabigatran. A standardized blunt liver injury (0 min) was performed and animals underwent hemorrhagic shock, 15 min later were randomized to receive idarucizumab (30, 60 or 120 mg/kg) or vehicle. Blood loss was measured at defined time points over 4 hrs post injury. At the same time points a standardized cut was made on the inner side of the ear using an adult Surgicutt® device, one cut for each method. Shed blood was collected from the wound site as it emerged over 4 min, placed in protease inhibitor solution and processed for FPA measurement by ELISA. For washed blood method, blood as it exited the wound in 10 sec intervals was diluted in saline into 96 wells and measured photometrically. AUC over 15 min was recorded as blood loss. Blood samples were collected over time to measure active dabigatran by diluted thrombin time (dTT). Data shown as mean ± SE. Results: Cumulative blood loss was 630 ± 56 mL in the placebo group and 2977 ± 129 mL in the dabigatran-treated group. There was a dose-dependent reduction in blood loss by 47% (1586 ± 253 mL), 64% (1064 ± 40 mL) and 62% (1140 ± 44 mL) following treatment with 30, 60 and 120 mg/kg idarucizumab (p<0.001). Dabigatran plasma levels were 1228 ± 320 ng/mL prior to injury with no significant differences between groups. Dabigatran activity decreased within 5 min of idarucizumab administration, with a dose-dependent reduction over 240 min and was completely inhibited with 120 mg/kg. FPA in blood from the wound in dabigatran-treated groups was decreased ~74% vs non-anticoagulated group (211.2 ± 86 vs 53.7 ± 13 ng/mL). FPA increased by 2.6-fold (136.3 ± 96 ng/mL), 1.4-fold (103.9 ± 59 ng/mL) and 6.2-fold (251.9 ± 139 ng/mL) over baseline following 30, 60 and 120 mg/kg idarucizumab, respectively. At 240 min, FPA levels were 12%, 25% and 52% of non-anticoagulated animals with increasing idarucizumab doses and correlated with levels of dabigatran at 240 min. Washed blood loss (AUC) in dabigatran-treated animals was increased ~7-fold prior to injury vs non-anticoagulated groups (2110 ± 420 vs 309.1 ± 11.2 OD*sec). There was a dose-dependent reduction in washed blood loss by 2.5% (1682 ± 688 OD*sec), 48% (889 ± 304 OD*sec), and 79% (370 ± 97 OD*sec) 30 min following 30, 60 and 120 mg/kg idarucizumab vs dabigatran-treatment (1724 ± 298 OD*sec). Washed blood loss was comparable to the non-anticoagulated group (186 ± 59 vs 281 ± 201 OD*sec) with 120 mg/kg idarucizumab after 240 min, also correlating with lack of dabigatran anticoagulant activity. Conclusions: This study shows that bleeding and its reversal with a dabigatran-specific antidote can be evaluated using alternative methods that measure FPA levels in shed blood and washed blood loss at non-trauma superficial wound sites. The reversal of blood loss and FPA generation correlated with reversal of bleeding from a trauma wound. These methods may serve as potential markers in experimental bleeding and trauma models to sensitively assess blood loss and to also monitor reversal agents. Disclosures Grottke: Boehringer Ingelheim : Consultancy, Research Funding; CSL Behring: Research Funding. Honickel:Boehringer Ingelheim : Travel support Other. Schurer:Boehringer Ingelheim Pharma GmbH & Co KG: Employment. van Ryn:Boehringer Ingelheim Pharma: Employment.

Comparison of the Antithrombotic Effectiveness of the Direct Thrombin Inhibitor, Dabigatran Etexilate, and Two Factor Xa Inhibitors in an A-V Shunt Model of Thrombosis in Rabbits.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3154-3154 ◽  
Author(s):  
Joanne van Ryn ◽  
Norbert Hauel ◽  
Henning Priepke ◽  
Kai Gerlach ◽  
Annette Schuler-Metz ◽  
...  
Keyword(s):  
Dabigatran Etexilate ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Direct Thrombin Inhibitor ◽  
Factor Xa Inhibitors ◽  
Thrombin Inhibitor ◽  
Factor Xa Inhibitor ◽  
Antithrombotic Activity ◽  
Antithrombotic Efficacy ◽  
Dose Dependent

Abstract Inhibition of two key serine proteases in the coagulation cascade, thrombin (IIa) and factor Xa, are currently being exploited for direct, oral antithrombotic activity in the clinic. However, it is still unclear if one form of coagulation factor inhibition is more effective than the other. Thus, the objective of this study was to test the antithrombotic efficacy of the clinically advanced compounds, the potent direct thrombin inhibitor, dabigatran etexilate and rivaroxaban, a potent direct factor Xa inhibitor in the rabbit A-V shunt model of thrombosis. In addition, another internally developed factor Xa inhibitor, BI42551, with properties similar to those in clinical development was tested. All three compounds have affinities (Ki) for their respective coagulation factor in the low nM range, i.e. human thrombin with dabigatran or human factor Xa with rivaroxaban or BI42551. In addition, each is at least >700-fold selective for its human coagulation factor, dabigatran etexilate for IIa vs Xa and the factor Xa inhibitors for Xa vs IIa. These compounds are highly selective inhibitors not only of the human enzyme, but also have similar values for rabbit thrombin and Xa, respectively. All experiments were performed according to German animal ethics guidelines. The femoral artery and vein of anesthetised rabbits were connected with polyethylene tubing containing a fixed length of suture, pre-soaked in tissue factor. Blood flow through the shunt was maintained over 40 min, after which the suture with any thrombus was removed from the shunt and weighed. The prodrug dabigatran etexilate and the factor Xa inhibitors were given in doses of 3 and 10 mg/kg orally and the rabbits were anesthetised either 90 min or at the highest dose, also 6.5 hrs after drug administration. There was a dose-dependent reduction of thrombus formation with all three compounds as compared to control. Antithrombotic efficacy at 3 and 10 mg/kg is shown as % inhibition of control measured 2 hrs after drug administration (table, columns 2&3). These effects were long-lasting, as significant antithrombotic activity was also measured 7 hrs post administration (last column). Plasma levels of all compounds were dose-dependent and clotting tests correlated well with dose. 3 mg/kg–2 hrs 10 mg/kg–2 hrs 10 mg/kg–7 hrs Dabigatran etexilate 61.7 ± 8.7 82.1 ± 5.5 59.5 ± 17.6 Rivaroxaban 43.2 ± 7.7 64.5 ± 8.1 41.0 ± 8.4 BI42551 31.1 ± 10.7 70.3 ± 3.3 39.9 ± 14.7 These results show that both thrombin and factor Xa inhibition are effective methods of inhibiting thrombosis in a rabbit AV shunt model. All drugs had potent and long-lasting effects after a single oral administration in this model, though dabigatran showed a trend to elevated antithrombotic efficacy at both 2 and 7 hrs. However, in the clinical setting differences in antithrombotic treatment may also be related to differences in pharmacokinetic profiles, drug interactions or metabolism, or the individual side effect profiles of each compound.

scholarly journals Antioxidant, anti-inflammatory and anticoagulant activities of three Thymus species grown in southeastern Morocco

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Abdelbassat Hmidani ◽  
Eimad Dine Tariq Bouhlali ◽  
Tarik Khouya ◽  
Mhamed Ramchoun ◽  
Younes Filali-Zegzouti ◽  
...  
Keyword(s):  
Anticoagulant Activity ◽  
Activated Partial Thromboplastin Time ◽  
Dependent Manner ◽  
Thrombin Time ◽  
Thymus Zygis ◽  
Wide Range ◽  
Thymus Satureioides ◽  
Anti Inflammatory ◽  
Dose Dependent

Abstract Background Thyme has been used for centuries in southeastern Morocco to treat a wide range of diseases such as inflammation disorders. The aim of the current study is to examine and to compare in vitro the anti-inflammatory, antioxidant, and anticoagulant activities of three thyme species grown in southeastern Morocco. Results Data showed that all studied species possess an important antioxidant activity: Thymus atlanticus (IC50 = 16.59 μg/mL), Thymus zygis (IC50 = 15.43 μg/mL), and Thymus satureioides (IC50 = 14.65 μg/mL). Concerning the anti-inflammatory activity, the highest effect was depicted in Thymus atlanticus followed by Thymus zygis and Thymus satureioides. With regard to the anticoagulant activity, the aqueous extract of these species prolongs activated partial thromboplastin time, prothrombin time, and thrombin time significantly (p < 0.05) in a dose-dependent manner. Conclusion Our results provide evidence that thymus extract exhibits marked antioxidant, anticoagulant, and anti-inflammatory effects, thus justifying the popular uses of these plants to treat some inflammatory and cardiovascular illnesses.

Evaluation of AR-H067637, the active metabolite of the new direct thrombin inhibitor AZD0837, in models of venous and arterial thrombosis and bleeding in anaesthetised rats

2010 ◽  
Vol 104 (12) ◽  
pp. 1242-1249 ◽  
Author(s):  
Susanne Pehrsson ◽  
Karin Johansson ◽  
Magnus Kjaer ◽  
Margareta Elg
Keyword(s):  
Blood Loss ◽  
Arterial Thrombosis ◽  
Bleeding Time ◽  
Thrombus Formation ◽  
Plasma Concentrations ◽  
Direct Thrombin Inhibitor ◽  
Thrombin Inhibitor ◽  
Coagulation Time ◽  
Dose Dependent ◽  
Anaesthetised Rats

SummaryAZD0837, currently in clinical development, is a once-daily oral anticoagulant that is bioconverted to AR-H067637, a selective, reversible direct thrombin inhibitor (DTI). When developing a new DTI, the anti-thrombotic effects are commonly investigated in in vivo animal models; this report shows the effect of AR-H067637 in venous and arterial thrombosis and bleeding models in anaesthetised rats. Thrombus formation was induced by topical application of ferric chloride to the carotid artery or to the caval vein with partial stasis. Cutaneous incision bleeding time and muscle transection blood loss were assessed, with or without acetylsalicylic acid (ASA). Activated partial thromboplastin time (APTT), ecarin coagulation time (ECT) and thrombin coagulation time (TCT) were used as plasma biomarkers of anticoagulant effect. Dalteparin was used as a reference compound. AR-H067637, given by continuous infusion, displayed a dose-dependent antithrombotic effect, with 50% inhibition (IC50) of thrombus size in venous and arterial thrombosis models obtained at plasma concentrations of 0.13 μM and 0.55 μM, respectively, without increased bleeding. Dose-dependent increased bleeding and blood loss were seen at plasma concentrations ≥1 μM AR-H067637. At the highest AR-H067637 plasma concentration tested, bleeding time and blood loss increased two and four times the vehicle group. Addition of ASA moderately potentiated bleeding time and blood loss. APTT, ECT and TCT were dose-dependently prolonged. These studies demonstrate that the DTI AR-H067637 inhibits thrombus formation in rat venous and arterial thrombosis models with no or minor increases in bleeding.

In-vitro profile and ex-vivo anticoagulant activity of the direct thrombin inhibitor dabigatran and its orally active prodrug, dabigatran etexilate

2007 ◽  
Vol 98 (07) ◽  
pp. 155-162 ◽  
Author(s):  
Jean-Marie Stassen ◽  
Henning Priepke ◽  
Uwe Joerg Ries ◽  
Norbert Hauel ◽  
Wolfgang Wienen
Keyword(s):  
Platelet Aggregation ◽  
Rhesus Monkeys ◽  
Ex Vivo ◽  
Anticoagulant Activity ◽  
Dabigatran Etexilate ◽  
Direct Thrombin Inhibitor ◽  
Thrombin Inhibitor ◽  
Orally Active

SummaryDabigatran is a reversible and selective, direct thrombin inhibitor (DTI) undergoing advanced clinical development as its orally active prodrug, dabigatran etexilate.This study set out to determine the molecular potency and anticoagulant efficacy of dabigatran and its prodrug dabigatran etexilate.This was achieved through enzyme inhibition and selectivity analyses, surface plasmon resonance studies, platelet aggregation, thrombin generation and clotting assays in vitro and ex vivo.These studies demonstrated that dabigatran selectively and reversibly inhibited human thrombin (Ki: 4.5 nM) as well as thrombin-induced platelet aggregation (IC50: 10 nM), while showing no inhibitory effect on other platelet-stimulating agents.Thrombin generation in platelet-poor plasma (PPP), measured as the endogenous thrombin potential (ETP) was inhibited concentration-dependently (IC50: 0.56 μM). Dabigatran demonstrated concentration-dependent anticoagulant effects in various species in vitro, doubling the activated partial thromboplastin time (aPTT), prothrombin time (PT) and ecarin clotting time (ECT) in human PPP at concentrations of 0.23, 0.83 and 0.18 μM, respectively. In vivo, dabigatran prolonged the aPTT dose-dependently after intravenous administration in rats (0.3, 1 and 3 mg/kg) and rhesus monkeys (0.15, 0.3 and 0.6 mg/kg). Dose- and time-dependent anticoagulant effects were observed with dabigatran etexilate administered orally to conscious rats (10, 20 and 50 mg/kg) or rhesus monkeys (1, 2.5 or 5 mg/kg), with maximum effects observed between 30 and 120 min after administration, respectively. These data suggest that dabigatran is a potent, selective thrombin inhibitor and an orally active anticoagulant as the prodrug, dabigatran etexilate.Footnote: Parts of this study were presented at the XVIII Congress of the International Society on Thrombosis and Haemostasis, Paris, July 2001. Thromb Haemost 2001; 86 (Suppl): Abstracts P755, P763.Institution where work was carried out: Boehringer Ingelheim Pharma GmbH &Co KG, 88397 Biberach, Germany.

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