Dabigatran Research Articles

Association of ABCB1 gene polymorphisms rs1128503, rs2032582, rs4148738 with anemia in patients receiving dabigatran after total knee arthroplasty

PurposeDabigatran is usually prescribed in recommended doses without monitoring of the blood coagulation for the prevention of venous thromboembolism after joint arthroplasty. ABCB1 is a key gene in the metabolism of dabigatran etexilate. Its allele variants are likely to play a pivotal role in the occurrence of hemorrhagic complications. MethodsThe prospective study included 127 patients with primary knee osteoarthritis undergoing total knee arthroplasty. Patients with anemia and coagulation disorders, elevated transaminase and creatinine levels as well as already receiving anticoagulant and antiplatelet therapy were excluded from the study. The association of ABCB1 gene polymorphisms rs1128503, rs2032582, rs4148738 with anemia as the outcome of dabigatran therapy was evaluated by single-nucleotide polymorphism analysis with a real-time polymerase chain reaction assay and laboratory blood tests. The beta regression model was used to predict the effect of polymorphisms on the studied laboratory markers. The probability of the type 1 error (p) was less than 0.05 was considered statistically significant. BenjaminiHochberg was used to correct for significance levels in multiple hypothesis tests. All calculations were performed using Rprogramming language v3.6.3. ResultsFor all polymorphisms there was no association with the level of platelets, protein, creatinine, alanine transaminase, prothrombin, international normalized ratio, activated partial thromboplastin time and fibrinogen. Carriers of rs1128503 (TT) had a significant decrease of hematocrit (p = 0.001), red blood count and hemoglobin (p = 0.015) while receiving dabigatran therapy during the postoperative period compared to the CC, CT. Carriers of rs2032582 (TT) had a significant decrease of hematocrit (p = 0.001), red blood count and hemoglobin (p = 0.006) while receiving dabigatran therapy during the postoperative period compared to the GG, GT phenotypes. These differences were not observed in carriers of rs4148738. ConclusionIt might be necessary to reconsider thromboprophylaxis with dabigatran in carriers of rs1128503 (TT) or rs2032582 (TT) polymorphisms in favor of other new oral anticoagulants. The long-term implication of these findings would be the reduction of bleeding complications after total joint arthroplasty.

The Potentially Significant Role of CYP3A-Mediated Oxidative Metabolism of Dabigatran Etexilate and its Intermediate Metabolites in Drug-Drug Interaction Assessments Using Microdose Dabigatran Etexilate.

Dabigatran etexilate (DABE), a double ester prodrug of dabigatran (DAB), is a probe substrate of intestinal P-glycoprotein (P-gp) commonly used in clinical drug-drug interaction (DDI) studies. When compared to its therapeutic dose at 150 mg, microdose DABE (375 µg) showed approximately 2-fold higher in DDI magnitudes with CYP3A/P-gp inhibitors. In this study, we conducted several in vitro metabolism studies to demonstrate that DABE at a theoretical gut concentration after microdosing significantly underwent NADPH-dependent oxidation (~40-50%) in parallel to carboxylesterase-mediated hydrolysis in human intestinal microsomes. Furthermore, NADPH-dependent metabolism of its intermediate monoester BIBR0951 was also observed in both human intestinal and liver microsomes, accounting for 100% and 50% of total metabolism, respectively. Metabolite profiling using LC-MS/MS confirmed the presence of several novel oxidative metabolites of DABE and of BIBR0951 in the NADPH-fortified incubations. CYP3A was identified as the major enzyme catalyzing the oxidation of both compounds. The metabolism of DABE and BIBR0951 was well described by Michaelis-Menten kinetics, with Km ranging 1-3 µM, significantly below the expected concentrations following the therapeutic dose of DABE. Overall, the present results suggested that CYP3A played a significant role in the presystemic metabolism of DABE and BIBR0951 following microdose DABE administration, thus attributing partly to the apparent overestimation in the DDI magnitude observed with the CYP3A/P-gp inhibitors. Therefore, DABE at the microdose, unlike the therapeutic dose, would likely be a less predictive tool and should be considered as a clinical dual substrate for P-gp and CYP3A when assessing potential P-gp-mediated impacts by dual CYP3A/P-gp inhibitors. Significance Statement This is the first study demonstrating a potentially significant role of CYP-mediated metabolism of the prodrug DABE following a microdose, but not a therapeutic dose. This additional pathway coupled with its susceptibility to P-gp may make DABE a clinical dual substrate for both P-gp and CYP3A at a microdose. The study also highlights the need for better characterization of the pharmacokinetics and metabolism of a clinical DDI probe substrate over the intended study dose range for proper result interpretations.

The polymorph landscape of dabigatran etexilate mesylate: Taking the challenge to bring a metastable polymorph to market

Dabigatran etexilate mesylate is polymorphic and can exist in different crystalline forms. Two polymorphs have been encountered during the development of this drug substance, namely anhydrous form I and anhydrous form II. Additionally, a hemihydrate was observed, if larger amounts of water were present during crystallization in the salt formation step. Finally, a high temperature form III can be obtained by heating anhydrous form I above 150 °C. All three at room-temperature accessible forms were characterized by means of microscopy, X-ray powder diffraction, thermal analysis, IR- and Raman spectroscopy. In addition, solubility parameters (equilibrium solubility and intrinsic dissolution rate, heat of solution) were collected on all three forms. The crystal structure of all three at room-temperature accessible forms could be obtained using electron diffraction. Anhydrous form I has a monoclinic crystal lattice (C2/c), anhydrous form II a triclinic one (P1¯), and the hemihydrate crystallizes also in a monoclinic space group (P2/c). From the obtained data there is clear evidence that anhydrous form II is thermodynamically more stable than anhydrous form I. Form I and form II are monotropically related to each other indicating that they may coexist over a wide temperature range. The hemihydrate is a completely independent crystalline modification of dabigatran etexilate mesylate. It is another thermodynamically stable form and structurally not related to the two anhydrous forms. The hemihydrate melts at ca. 125 °C, there is no conversion to either anhydrous form I or form II upon dehydration. The high temperature form III is enantiotropically related to form I and only stable above the phase transition temperature at ca. 150 °C and its melting point at ca. 183 °C. The energy difference between anhydrous form I and form II was found to be only 2.5 – 3.0 J/g. Both forms have very similar aqueous solubility characteristics. Although anhydrous form II is the thermodynamically more stable form, anhydrous form I was chosen for development. The selection of form I for development was mainly based on the superior bulk processing properties of anhydrous form I in drug substance synthesis and further drug product processing as well as its slightly better chemically stability in pivotal long term stability studies. Anhydrous form I, although meta stable, is still stable enough that conversion to the more stable form II can occur only to a limited extent during drug substance synthesis and drug product manufacturing. From long term stability data on both bulk drug substance as well as drug product, there is no indication that form I transforms to form II during storage. Even under stress conditions where form I was stored up to 4 weeks at 70 °C, no conversion to form II was observed.

Clinical experience with idarucizumab in patients with atrial fi brillation taking dabigatran etexilate

Dabigatran etexilate (DE) is a direct thrombin inhibitor that has been shown to be eff ective and safe in preventing thrombotic events in a number of studies. Currently idarucizumab, which is a monoclonal antibody and a DE antagonist, is used to immediately inactivate the DE-induced eff ect.Objective. Еvaluation of the effi ciency and safety of idarucizumab in patients receiving DE.Material and methods. 6 patients (2 men, 4 women) aged 61 to 86 years (mean age 72.8 ± 10.6 years) receiving DE, who are expected to use idarucizumab in achieving the goal of sTLT or surgery.Results. In none of the patients the use of idarucizumab was accompanied by a decrease in thrombin time of less than 11 seconds which could indicate a hypercoagulable phenomenon. Before inactivation of dabigatran etexilate thrombin time was signifi cantly higher (p < 0.05) than after the administration of the drug. There were no statistically signifi cant diff erences in the concentration of D-dimer before and after the administration of idarucizumab which indicates the absence of procoagulant properties of this drug. None of the patients developed clinically signifi cant arterial and/ or venous thrombotic events such as recurrent IS, myocardial infarction, deep vein thrombosis of the lower extremities and pulmonary embolism, during the entire period of hospitalization.Conclusion. The use of idarucizumab is allowed for systemic thrombolytic therapy and emergency surgical treatment in patients taking DE. Idarucizumab quickly and safely neutralizes the anticoagulant eff ect of DE and doesn’t have a prothrombotic activity.

Evaluation of the Potential for Cytochrome P450 and Transporter-Mediated Drug-Drug Interactions for Cilofexor, a Selective Nonsteroidal Farnesoid X Receptor (FXR) Agonist.

Cilofexor is a selective farnesoid X receptor (FXR) agonist in development for the treatment of nonalcoholic steatohepatitis and primary sclerosing cholangitis. Our objective was to evaluate potential drug-drug interactions of cilofexor as a victim and as a perpetrator. In this Phase 1 study, healthy adult participants (n = 18-24 per each of the 6 cohorts) were administered cilofexor in combination with either perpetrators or substrates of cytochrome P-450 (CYP) enzymes and drug transporters. In total, 131 participants completed the study. As a victim, cilofexor area under the curve (AUC) was 651%, 795%, and 175% when administered following single-dose cyclosporine (600 mg; organic anion transporting polypeptide [OATP]/P-glycoprotein [P-gp]/CYP3A inhibitor), single-dose rifampin (600 mg; OATP1B1/1B3 inhibitor), and multiple-dose gemfibrozil (600 mg twice daily [BID]; CYP2C8 inhibitor), respectively, compared with the administration of cilofexor alone. Cilofexor AUC was 33% when administered following multiple-dose rifampin (600 mg; OATP/CYP/P-gp inducer). Multiple-dose voriconazole (200 mg BID; CYP3A4 inhibitor) and grapefruit juice (16 ounces; intestinal OATP inhibitor) did not affect cilofexor exposure. As a perpetrator, multiple-dose cilofexor did not affect the exposure of midazolam (2 mg; CYP3A substrate), pravastatin (40 mg; OATP substrate), or dabigatran etexilate (75 mg; intestinal P-gp substrate), but atorvastatin (10 mg; OATP/CYP3A4 substrate) AUC was 139% compared with atorvastatin administered alone. Cilofexor may be coadministered with inhibitors of P-gp, CYP3A4, or CYP2C8 without the need for dose modification. Cilofexor may be coadministered with OATP, BCRP, P-gp, and/or CYP3A4 substrates-including statins-without dose modification. However, coadministration of cilofexor with strong hepatic OATP inhibitors, or with strong or moderate inducers of OATP/CYP2C8, is not recommended.

Investigation of Solid-State Hydrate-Anhydrous Phase Transformations of Dabigatran Etexilate Hemi-Edisylate

In this study, a dabigatran etexilate edisylate (DBE) was prepared by the reaction crystallization of dabigatran etexilate (DBG) and edisilic acid. According to single crystal X-ray diffraction (SXRD), it was revealed that two DGB were combined with one edisylate and associated with one water for DBE monohydrate. Additionally, the hot stage microscopy showed that the DBE monohydrate was transformed to DBE amorphous solid and then finally shifted to the DBE anhydrate in solid-state. Using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and a hygroscopic test, it was confirmed that the phase transformation of DBE monohydrate to DBE anhydrate was irreversible. Additionally, any other crystal form of DBE anhydrate was not available because it was the most stable phase.

Effects of Simvastatin on Pharmacokinetics and Anticoagulant Effects of Dabigatran in Healthy Subjects.

Higher risk of major hemorrhage associated with concomitant use of dabigatran and simvastatin compared to other statins was previously reported with a suggestion of P-glycoprotein-mediated interaction. The aim of this study was to evaluate the effects of simvastatin on pharmacokinetics and anticoagulant effects of dabigatran, a direct oral anticoagulant. A total of 12 healthy subjects were enrolled in an open-label, two-period, single sequence study. Subjects were given 150 mg of dabigatran etexilate followed by 40 mg of once-daily simvastatin for seven days. Dabigatran etexilate was administered with simvastatin on the seventh day of simvastatin administration. Blood samples for pharmacokinetic and pharmacodynamic analyses were obtained until 24 h post-dose of dabigatran etexilate with or without co-administration of simvastatin. Pharmacokinetic parameters were derived from noncompartmental analysis for dabigatran etexilate, dabigatran, and dabigatran acylglucuronide. When simvastatin was co-administered, geometric mean ratios of area under time-concentration curves for dabigatran etexilate, dabigatran, and dabigatran acylglucuronide were 1.47, 1.21, and 1.57, respectively, compared to when dabigatran etexilate was administered alone. Thrombin generation assay and coagulation assay showed similar profiles between before and after co-administration of simvastatin. This study provides evidence that simvastatin treatment plays a minor role in modulating pharmacokinetics and anticoagulant effects of dabigatran etexilate.

Discovery and development of Factor Xa inhibitors (2015-2022).

As a pathological coagulation process, thrombus can lead to many serious diseases, including ischemic stroke, acute myocardial infarction (AMI), acute coronary syndrome (ACS), and deep venous thrombosis (DVT). And anticoagulant drugs are one of the most effective ways to prevent and treat these diseases. Although macromolecular anticoagulant drugs such as low molecular weight heparins (LMWHs) are widely used in the clinic, their characteristics of requiring injectable use hinder their further promotion in the clinic, and the disadvantages of oral anticoagulant drugs, such as warfarin and dabigatran etexilate, which can easily cause bleeding adverse effects, are also not addressed. Factor Xa (FXa) has gained attention because it lies at the intersection of the coagulation cascade pathways, whereas subsequently introduced Factor Xa inhibitors such as rivaroxaban and apixaban, among others, have gained market popularity because of their high potency for anticoagulation and high specificity for Factor Xa when administered orally. But some of the drawbacks that these Factor Xa inhibitors have simultaneously such as fewer indications and the lack of an effective reversal drug when bleeding occurs are urgently addressed. The development of new Factor Xa inhibitors therefore becomes one means of addressing these questions. This article summarizes the small molecule Factor Xainhibitors developed from 2015 to 2022, classifies them according to their scaffolds, focuses on the analysis of their structure-activity relationships, and provides a brief assessment of them.

Comparative study of predisposition to thrombosis with administration of known systemic hemostatic agents and fibrin monomer in the experiment

Aim. To compare predisposition to thrombosis caused by administration of known systemic hemostatic agents and fibrin monomer under the conditions of normal coagulation versus drug-induced hypocoagulation in the experiment.Materials and methods. The prothrombotic effect of intravenous (IV) administration of various systemic hemostatic agents was compared in a series of in vivo experiments. These agents included fibrin monomer (FM) (0.25 mg / kg), prothrombin complex concentrate (PCC) (40 IU / kg) or recombinant factor VIIa (rFVIIa) (270 mcg / kg). The studies were conducted under the conditions of hypocoagulation induced by the administration of warfarin (per os at a dose of 0.4–0.5 mg / kg / day for 14 days) or dabigatran etexilate (per os at a single dose of 15–20 mg / kg). Hemostatic system parameters were evaluated using thromboelastometry and calibrated automated thrombography.Results. It was found that PCC reversed anticoagulant effects and led to an overcompensated increase in the density characteristics of the blood clot along with an excessive increase in thrombin generation in the groups of animals with warfarin-induced coagulopathy. The use of PCC and rFVIIa in the groups of animals with dabigatran-induced hypocoagulation also resulted in an increase in blood thrombogenic properties. In the administration of PCC, it was manifested though an increased D-dimer level and in administration of rFVIIa – through an increase in the clot density characteristics. At the same time, replacement of these hemostatic agents with FM did not affect the hemostatic system parameters.Conclusion. FM at a dose of 0.25 mg / kg, as opposed to PCC and rFVIIa, is safer in terms of the risk of thrombosis.

Pharmacoeconomic analysis of antithrombotic therapy in patients with acute coronary syndrome and patients with atrial fibrillation who underwent percutaneous coronary intervention

Objective: to assess the clinical and economic feasibility of ticagrelor in combination with acetylsalicylic acid (ASA) in comparison with clopidogrel in combination with ASA in patients with acute coronary syndrome (ACS), including both those who underwent, and those who did not undergo percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG); and new oral anticoagulants (NOACs) in combination with clopidogrel in comparison with warfarin in combination with clopidogrel and ASA in patients with atrial fibrillation (AF) who underwent PCI; to identify the impact of the above strategies of antithrombotic therapy on the targets of the State Health Care Program of the Russian Federation (RF) “Development of Health Care” and the Federal Project “Cardiovascular Diseases Control”.Material and methods. The clinical and economic study (CES) of ticagrelor in combination with ASA in ACS patients was based on a costbenefit analysis. A combined model, including a decision tree and Markov model was developed. The horizon period of the analysis was 5 years. Quality-adjusted life year (QALY) was used as an efficiency criterion and only the direct medical costs associated with the conditions identified in the modeling were taken into account. A discount rate of 5% was taken into account during the CES. The application of NOACs in combination with clopidogrel was studied in the CES using a cost minimization analysis considering the costs per patient characterized by the presence of AF regardless of the presence of ACS and a history of PCI.Results. We used a decision tree and Markov modeling in adult patients with ACS, who had or had not undergone PCI or CABG, in the horizon period of 5 years considering the discount rate of the added quality-adjusted life year (incremental cost-effectiveness ratio (ICER) per QALY). The result for ticagrelor in combination with ASA compared to clopidogrel in combination with ASA was 605,199 rubles, which was significantly lower than the willingness-to-pay threshold (2,235,201 rubles). Assessment of the impact of the therapy regimen including ticagrelor in combination with ASA on the target indicators of the State Health Care Program of the RF “Development of Healthcare” and the Federal Project “Cardiovascular Diseases Control” showed that the use of this therapy regimen will reduce mortality from myocardial infarction (MI) and cardiovascular causes by 2.45 cases per 100 thousand population provided that 100% of patients with MI and unstable angina in the RF are transferred from clopidogrel + ASA scheme to ticagrelor + ASA. The potential contribution of ticagrelor in combination with ASA compared to clopidogrel in combination with ASA in patients with ACS in achieving the target reduction of mortality from circulatory diseases will be 6.48% by 2023. In all simulated scenarios, in the group of patients with AF who had undergone PCI, pharmacotherapy regimens containing NOACs (dabigatran etexilate, rivaroxaban, apixaban) were more costly than therapy regimens containing warfarin (with not significantly different effectiveness).Conclusion. The results of the evaluation of clinical and economic feasibility of antiplatelet therapy strategies demonstrated the costeffectiveness of ticagrelor in combination with ASA compared to clopidogrel in combination with ASA in patients with ACS, including those who had undergone PCI or CABG and those who had not. The strategy of ticagrelor + ASA showed a favorable effect on the rates of mortality from MI, as well as from circulatory diseases. The results of the clinical and economic evaluation of the four strategies of antithrombotic drug therapy in patients with AF who had undergone PCI showed higher costs of the regimens containing NOACs with a presumed zero effect on the mortality from circulatory diseases.

Physiologically-based pharmacokinetic modeling to predict drug-drug interactions of dabigatran etexilate and rivaroxaban in the Chinese older adults

IntroductionDrug-drug interaction (DDI) is one of the major concerns for the clinical use of NOACs in the older adults considering that coexistence of multiple diseases and comorbidity were common. Current guidelines on the DDI management were established based on clinical studies conducted in healthy adults and mainly focus on the Caucasians, whereas systemic and ethnic differences may lead to distinct management in the Chinese older adults. ObjectivesTo investigate the impact of aging on the DDI magnitude between P-gp and/or CYP3A4 inhibitors with dabigatran etexilate and rivaroxaban in older adults, providing additional information for the use in clinical practice. ResultsCompared with the simulated adult, the AUC of the simulated older adults increased by 42–88% (DABE) and 21–60% (rivaroxaban), respectively, during NOACs monotherapy. Simulation on DDIs predicted that verapamil and clarithromycin further increase the exposure of dabigatran by 29–72% and 40–47%, whereas clarithromycin, fluconazole, and ketoconazole increase the exposure of rivaroxaban by 21–30%, 16–24%, and 194–247% in the older adults. Overall, our simulation result demonstrated that aging and DDIs both increased the exposure of NOACs. However, aging does not have a drastic impact on the extent of DDIs. The DDI ratios of young and old older adults were similar to the adults and were also similar between Caucasians and Chinese. DiscussionWe further simulated the interactions under steady-state based on the EHRA guideline (2021). Our simulation results revealed that recommended reduced dosing regimen of dabigatran etexilate during comedication with verapamil and clarithromycin (110 and 75 mg BID for Chinese young and old older adults) will result in exposure (trough concentration) that was either slightly higher or similar to the trough concentration of patients with any bleeding events. Routine monitoring of bleeding risk is encouraged. Further studies on the use of rivaroxaban in Chinese older adults are warranted. ConclusionAging and DDI increases exposure of drug in Chinese older adults. However, aging does not have a drastic impact on the extent of DDIs. Clinical management of DDIs in Chinese older adults in the absence of complex polypharmacy can a priori be similar to the EHRA guideline but routine monitoring of bleeding risk is encouraged when dabigatran etexilate given with verapamil and clarithromycin.

Comparative differences in the risk of major gastrointestinal bleeding among different direct oral anticoagulants: An updated traditional and Bayesian network meta-analysis.

Background: The most favorable gastrointestinal (GI) bleeding safety profile among different types of direct oral anticoagulants (DOACs) remains controversial. This meta-analysis includes the latest studies and aims to compare GI bleeding risk associated with the use of various DOACs. Methods: PubMed, Cochrane library, and clinicaltrial.gov were searched. Randomized control trials (RCTs) evaluating the safety of DOACs were identified. The primary endpoint assessed was major GI bleeding. Results: A total of 37 RCTs were included in the analyses. Based on the traditional meta-analysis, the major GI bleeding risk was different among various DOACs (interactive p-value <.10). Network meta-analysis findings showed that no DOACs increased the risk of major GI bleeding compared with conventional therapy. Furthermore, a 10mg daily administration of apixaban reduced the major GI bleeding risk more than daily doses of 60mg edoxaban, ≥15mg rivaroxaban, and 300mg dabigatran etexilate. No difference was observed between daily doses of 300mg dabigatran etexilate, 60mg edoxaban, and ≥15mg rivaroxaban. The major GI bleeding risk associated with 30mg daily dose of edoxaban was lower than with 10mg daily rivaroxaban, and no differences between daily 5mg apixaban, 30mg edoxaban, and 220mg dabigatran etexilate were observed. Conclusion: Differences in the major GI bleeding risk were observed when various DOACs were compared. Among standard-dose DOACs, apixaban was associated with the lowest degree of major GI risk. Among low-dose DOACs, edoxaban was associated with a lower major GI bleeding risk than rivaroxaban.

Medications mostly associated with hematuria: assessment of the EudraVigilance and Food and Drug Administration pharmacovigilance databases entries.

Drugs may have a direct causative role in triggering hematuria. The range of medications which may be responsible for hematuria is wide, but little is known on those which are most frequently involved. The aim of our study was to identify and compare drugs mostly related with hematuria. The Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) database and the EudraVigilance (EV) database were queried to identify the drugs which were associated the most with hematuria individual reports till 30 September 2021. Rivaroxaban, aspirin, warfarin sodium, clopidogrel bisulfate, dabigatran etexilate mesylate, apixaban, warfarin, cyclophosphamide, lansoprazole, enoxaparin sodium, and ibuprofen were analyzed. Analysis per gender, age and severity was performed. Disproportional analysis was performed to compare drugs. Overall, 15,687 reports of hematuria were recorded in the FDA database and 15 007 in the EV database. Rivaroxaban and Warfarin appear to be the most dangerous medications in terms of hematuria when compared to the other medications (PRR>1, P<0.05) while apixaban is the safest one (PRR<1, P<0.05) when compared to the other medications. In terms of severity only 162/15 007 (1.08%) were fatal. Between the drugs analyzed cyclophosphamide 7.2%, enoxaparin (3%) and dabigatran (2.5%) presented a higher number of fatal hematuria episodes when compared to the other drugs (<1%). Anticoagulants and antiplatelets are more frequently related to hematuria episodes however some differences exist between them. Particularly warfarin and rivaroxaban should be prescribed with caution in patients at increased risk of hematuria. Prescribers should inform those treated with these medications about the risk of hematuria and its sequelae.

Edoxaban, a Factor Xa-Specific Direct Oral Anticoagulant, Significantly Suppresses Tumor Growth in Colorectal Cancer Colon26-Inoculated BALB/c Mice.

Introduction Certain low-molecular-weight heparins have been reported to reduce tumor growth and metastasis in tumor cell-inoculated mouse models and cancer patients. Recently, direct oral anticoagulants (DOACs) have been widely used in patients with thromboembolism. This study was aimed at investigating the effect of DOACs, which target thrombin or factor Xa, on tumor growth in a syngeneic mouse model comprising BALB/c mice inoculated with colon cancer Colon26 cells. Materials and Methods DOACs targeting thrombin (dabigatran etexilate [DABE]) or factor Xa (rivaroxaban [RVX] and edoxaban [EDX]) were orally administered daily to male BALB/c mice inoculated with Colon26 cells, followed by analyses of tumor growth and plasma levels of coagulation- and tumor-related factors such as tissue factor (TF), plasminogen activator inhibitor-1 (PAI-1), interleukin-6 (IL-6), and matrix metalloproteinase-2 (MMP-2). Results Colon26 cells expressed significant amounts of functionally active TF. Tumor growth in Colon26-inoculated mice was significantly suppressed in DABE- or RVX-treated mice ( p <0.05) and was suppressed more significantly in EDX-treated mice ( p <0.01). Therefore, the antitumor mechanism of action of EDX was investigated next. Plasma levels of TF, PAI-1, IL-6, and MMP-2 were elevated in Colon26-inoculated mice but were significantly reduced in EDX-treated mice ( p <0.01). The expression of protease-activated receptor (PAR)1, PAR2, signal transducer and activator of transcription-3 (STAT3), cyclin D1, and Ki67 was increased in tumor tissue of Colon26-inoculated mice but (except for PAR1) was significantly decreased in tumor tissues of EDX-treated mice ( p <0.01). In addition, apoptotic cells and p53 protein levels were significantly increased in tumor tissues of EDX-treated mice. Conclusion The data suggest that among the tested DOACs, EDX significantly suppresses tumor cell proliferation via the factor Xa-PAR2 pathway, which is activated by coagulation and inflammation in Colon26-inoculated mice and induces tumor cell apoptosis.

Study of dabigatran etexilate polymorphs for improved manufacturing processability

In the present work on anhydrous form-I and tetrahydrate form of Dabigatran etexilate a comparative study was done to seek a polymorph which will perform better in downstream processing and dissolution. Anhydrous form I of Dabigatran etexilate used in this study is having a needle shape. Tetrahydrate form was recrystallized from the anhydrous form I by solvent recrystallization using a slow evaporation method with acetone at NMT 25 °C, 2–8 °C, and −20 °C. The crystal shape of recrystallized tetrahydrate form was tabular. Scanning electron microscopy (SEM) was used to confirm the shape of crystals. Powder X-ray Diffraction (PXRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Fourier Transform Infrared Spectroscopy (FTIR) analysis confirmed polymorphic change. Flow characterization indicates that tetrahydrate has better bulk density, tapped density, Hausner ratio, and Cars index than anhydrous form I. Kawakita analysis shows that tetrahydrate has better compactibility and lesser cohesive nature than anhydrous form I. Heckel plots indicates tendency of tetrahydrate form to undergo plastic deformation linearly as pressure increases compared to anhydrous form I. The tensile strength of tetrahydrate is better than anhydrous form I and it also have a lesser tendency for capping and lamination at higher compression pressure. A dissolution study in USP dissolution media for dabigatran etexilate showed that tetrahydrate has a higher dissolution rate than anhydrous form I which is also backed by higher solubility. Overall, the tetrahydrate form can be preferred over the anhydrous form I during polymorph selection.

Novel inhibitors of breast cancer resistance protein (BCRP, ABCG2) among marketed drugs

Drug-drug interactions (DDIs) are a major concern for the safe use of medications. Breast cancer resistance protein (BCRP) is a clinically relevant ATP-binding cassette (ABC) transporter for drug disposition. Inhibition of BCRP increases the plasma concentrations of BCRP substrate drugs, which potentially could lead to adverse drug reactions. The aim of the present study was to identify BCRP inhibitors amongst a library of 232 commonly used drugs and anticancer drugs approved by the United States Food and Drug Administration (FDA). BCRP inhibition studies were carried out using the vesicular transport assay. We found 75 drugs that reduced the relative transport activity of BCRP to less than 25% of the vehicle control and were categorized as strong inhibitors. The concentration required for 50% inhibition (IC50) was determined for 13 strong inhibitors that were previously poorly characterized for BCRP inhibition. The IC50 ranged from 1.1 to 11 µM, with vemurafenib, dabigatran etexilate and everolimus being the strongest inhibitors. According to the drug interaction guidance documents from the FDA and the European Medicines Agency (EMA), in vivo DDI studies are warranted if the theoretical intestinal luminal concentration of a drug exceeds its IC50 by tenfold. Here, the IC50 values for eight of the drugs were 100-fold lower than their theoretical intestinal luminal concentration. Moreover, a mechanistic static model suggested that vemurafenib, bexarotene, dabigatran etexilate, rifapentine, aprepitant, and ivacaftor could almost fully inhibit intestinal BCRP, increasing the exposure of concomitantly administered rosuvastatin over 90%. Therefore, clinical studies are warranted to investigate whether these drugs cause BCRP-mediated DDIs in humans.

Thrombin Generation Is Differentially Affected By Anticoagulants in Patients with Acute Lymphoblastic Leukemia - an Ex-Vivo Study

Background: Venous thromboembolism (VTE) is a frequent complication in patients with acute lymphoblastic leukemia (ALL). Low molecular weight heparin (LMWH) reduces the risk of VTE in ALL, but is not well tolerated in children. VTE rates remain unacceptably high in adults despite LMWH prophylaxis. Thus, novel strategies for VTE prevention are warranted. In the primary analysis of the PREVAPIX-ALL trial there was no statistically significant reduction in VTE among children treated with the oral factor Xa inhibitor, apixaban, compared to no anticoagulation (AC). Comparative data on activity of different anticoagulants are needed to guide planning of VTE prophylaxis trials. Aims: To characterize and compare the ex-vivo effect of LMWH (enoxaparin), oral direct factor Xa inhibitors (apixaban, rivaroxaban) and oral direct thrombin inhibitor (dabigatran etexilate) in ALL patients' samples using thrombin generation (TG). Methods: A prospective observational cohort study of 46 children with newly-diagnosed ALL, treated with the L-asparaginase (ASP)-based BFM protocol, at a tertiary medical center. Patients on therapeutic-dose AC at baseline were excluded. Blood samples were drawn before ASP treatment (ALL-Day0) and 7 days after (ALL-Day7). Normal pooled plasma (NP) was collected from healthy adult volunteers. Samples were spiked ex-vivo with enoxaparin [0.2 U/mL], apixaban [39 ng/mL], rivaroxaban [39 ng/mL] and dabigatran [150 ng/mL] or vehicle (i.e., control). AC concentrations chosen based on 50% peak reduction (for Xa inhibitors) or 200% LT prolongation (for dabigatran) in NP. Subsequently, TG was performed initiated using 5 pM tissue factor in the presence of 4 µM phospholipids using Calibrated Automated Thrombogram method in these samples. Results are expressed as peak height (PH) and lag time (LT) and relative reduction or prolongation (% difference in PH or LT, respectively) in plasma samples spiked with anticoagulants compared to control. Reduction in PH reflects enoxaparin, apixaban and rivaroxaban activity, while LT prolongation indicates dabigatran activity. This report focuses on measures reflecting the activity of each drug. Descriptive statistics were used to show the median [interquartile range (IQR)] for continuous variables and percentages for categorical data. T-Test / Mann-Whitney U test and paired T-test / Wilcoxon test used to compare between paired and non-paired samples, respectively. Results: Selected sample characteristics are as follows: median age, 7.75 years [IQR 3.73-11.93]; 19 (41%) females; median BMI, 16.8 [IQR 15.5-19.9]; B-cell precursor immunophenotype in 33 (71.7%) and T-cell in 13 (28.3%); prior VTE in 1 (2%). Median PH [IQR] in control samples (without AC) was 256.6 [252.6-265.3] nmol/l, 396.0 [347.2-464.7] nmol/l and 354.4 [307.1-407.4] nmol/l in NP, ALL-Day0 and ALL-Day7 respectively. Median LT [IQR] in control samples was 2.7 [2.5-2.83] nmol/l, 1.8 [1.7-2.3] nmol/l and 1.7 [1.6-2] nmol/l in NP, ALL-Day0 and ALL-Day7 respectively. Median % differences in PH and LT between samples spiked with different anticoagulants and controls are shown in Figure 1A and Figure 1B, respectively. Enoxaparin, apixaban and rivaroxaban reduced PH in NP, ALL-Day0 and ALL-Day7 samples (p<0.0005). There was less reduction in PH with enoxaparin, apixaban and rivaroxaban in ALL-Day0 samples than in NP (p=0.029, p<0.0005, p<0.0005 respectively), suggesting reduced anticoagulant activity in ALL patients compared to subjects without ALL. LT was prolonged with dabigatran in NP, ALL-Day0 and ALL-Day7 samples (p<0.05). Dabigatran resulted in a similar LT prolongation in ALL-Day0 and NP (p=0.677), suggesting a preserved AC effect in ALL. There was less LT prolongation in ALL-Day7 (134% [123-175%] than in ALL-Day0 (180% [134-238]; p=0.031). This reflects an ongoing dabigatran effect after ASP, albeit to a lesser degree. Conclusions: Our ex-vivo results suggest limited anticoagulant activity of enoxaparin and lack of anticoagulant activity of apixaban and rivaroxaban (both factor Xa inhibitors) in preventing VTE in ALL, in line with prior clinical data. In contrast, dabigatran etexilate, an oral direct thrombin inhibitor not previously tested in ALL, exhibited preserved anticoagulant activity in ALL patients, even after exposure to ASP. This may suggest that dabigatran should be investigated in clinical studies for the unmet need of VTE prophylaxis in ALL. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Assessment of Aging-Related Function Variations of P-gp Transporter in Old-Elderly Chinese CHF Patients Based on Modeling and Simulation.

P-glycoprotein (P-gp) is one of the most intensely studied transporters owing to its broad tissue distribution and substrate specificity. Existing research suggests that the risk of systemic exposure to dabigatran etexilate (DABE) and digoxin, two P-gp probe substrates in vivo, has significantly increased in elderly patients. We applied a model-based quantitative pharmacological approach to assess aging-related P-gp changes in the Chinese old-elderly population. Population pharmacokinetic (PopPK) modeling was first performed using clinical pharmacokinetic data to explore the effect of age on the pharmacokinetic characteristics of dabigatran (DAB, the active principle of DABE) and digoxin in elderly Chinese patients. Corresponding physiologically based pharmacokinetic (PBPK) models were established to further explain the elevated systemic exposure to these two drugs. Eventually, standard dosing regimens of DABE and digoxin were assessed in Chinese old-elderly patients with chronic heart failure (CHF) with different stages of renal impairment. PopPK analysis suggested that age as a covariate had an additional effect on the apparent clearance of these two drugs after correcting for creatinine clearance. PBPK simulation results suggested that disease-specific pathophysiological changes could explain DAB exposure in the young elderly. In the elderly population, 17.1% of elevated DAB exposure remained unexplained, and 25.5% of the reduced P-gp function associated with aging was ultimately obtained using sensitivity analysis. This value was further validated using digoxin data obtained by PBPK modeling. The simulation results suggest that CHF patients with advanced age and moderate-to-severe renal impairment require heightened vigilance for elevated exposure risk during the use of DABE and digoxin. Aging might be a significant risk factor for elevated systemic exposure to DAB and digoxin by reducing P-gp-mediated efflux in the Chinese old elderly population.

Preclinical testing of dabigatran in trypsin-dependent pancreatitis.

Pancreatitis, the inflammatory disorder of the pancreas, has no specific therapy. Genetic, biochemical, and animal model studies revealed that trypsin plays a central role in the onset and progression of pancreatitis. Here, we performed biochemical and preclinical mouse experiments to offer proof of concept that orally administered dabigatran etexilate can inhibit pancreatic trypsins and shows therapeutic efficacy in trypsin-dependent pancreatitis. We found that dabigatran competitively inhibited all human and mouse trypsin isoforms (Ki range 10-79 nM) and dabigatran plasma concentrations in mice given oral dabigatran etexilate well exceeded the Ki of trypsin inhibition. In the T7K24R trypsinogen mutant mouse model, a single oral gavage of dabigatran etexilate was effective against cerulein-induced progressive pancreatitis, with a high degree of histological normalization. In contrast, spontaneous pancreatitis in T7D23A mice, which carry a more aggressive trypsinogen mutation, was not ameliorated by dabigatran etexilate, given either as daily gavages or by mixing it with solid chow. Taken together, our observations showed that benzamidine derivatives such as dabigatran are potent trypsin inhibitors and show therapeutic activity against trypsin-dependent pancreatitis in T7K24R mice. Lack of efficacy in T7D23A mice is probably related to the more severe pathology and insufficient drug concentrations in the pancreas.

Dabigatran etexilate is efficacious in consumptive coagulopathy and pain associated with venous malformations

ObjectiveConsumptive coagulopathy treatment and pain management are crucial for patients with venous malformations (VMs). Dabigatran etexilate, a non–vitamin K antagonist oral anticoagulant, has known advantages compared with low-molecular-weight heparin and vitamin K antagonists, including oral administration, a more consistent pharmacokinetics/pharmacodynamics profile, a better safety profile, and no need for coagulation surveillance. In the present study, we tested the efficacy and safety of dabigatran etexilate for consumptive coagulopathy treatment and pain management for patients with VMs. MethodsTo investigate the efficacy and safety of dabigatran etexilate in treating localized intravascular coagulation (LIC) associated with VM, we retrospectively collected data for 19 outpatients with VM and LIC, who had been treated with dabigatran etexilate from September 2019 to June 2021. The patients provided oral informed consent and underwent biologic blood testing, routine examinations, and determination of coagulation function before and after treatment. The dosage of dabigatran etexilate was 110 mg twice daily for adults and 55 mg twice daily for children. ResultsAll 19 patients had benefited from dabigatran etexilate treatment with coagulation improvement and pain relief. Pain had improved in all 16 evaluable patients. The fibrinogen and D-dimer levels had improved in 18 of 19 patients. The fibrin degradation product level had improved in 10 of 14 patients. None of patients reported lesion regression, appearance changes, or improvement in mobility. No significant differences were found in the D-dimer, fibrinogen, and fibrin degradation product levels between the short-term (<10 days) and long-term (≥10 days) use of the medication. Dabigatran etexilate was well tolerated by all patients. No bleeding event had occurred during follow-up. ConclusionsThe results of our study have confirmed the efficacy and safety of dabigatran etexilate in treating pain and LIC in patients with VMs. Dabigatran etexilate is a suitable choice preoperatively to modify coagulation function and pain in patients with VMs.