Dabigatran Acylglucuronide, the Major Metabolite of Dabigatran, Shows a Weaker Anticoagulant Effect than Dabigatran

Dabigatran attenuates methotrexate-induced hepatotoxicity by regulating coagulation, endothelial dysfunction, and the NF-kB/IL-1β/MCP-1 and TLR4/NLRP3 signaling pathways

This study examines Dabigatran's (Dab) capacity to mitigate methotrexate (MTX)-induced coagulation disorders and endothelial dysfunction, while exploring its effects on oxidative stress and inflammatory pathways (NF-kB/IL-1β/MCP-1, TLR4/NLRP3) in reducing hepatotoxicity. Rats were assigned to four groups: a control group receiving saline intraperitoneally (i.p.); an MTX group with a single MTX dose (20 mg/kg, i.p.) to induce hepatotoxicity; and two pretreatment groups receiving Dab orally at 15 mg/kg and 25 mg/kg for seven days before and 4 days after MTX administration. MTX-treated rats showed significant increases in liver enzymes (ALT, AST, ALP) and reductions in antioxidant enzymes (SOD, GSH), along with elevated coagulation parameters (tissue factor (TF), thrombin, fibrin, plasminogen activator inhibitor-1 (PAI-1)), leading to coagulation disorders. Endothelial dysfunction was evident with reduced eNOS expression, while inflammation increased through elevated iNOS, ICAM-1, and pro-inflammatory cytokines (MPO, NF-kB, TNF-α, IL-1β, MCP-1), alongside activation of the TLR4/NLRP3 inflammasome pathway and decreased IL-10 (p < 0.05). Immunohistochemistry revealed increased cytochrome c and caspase-3 expression, with histopathological damage. Dabigatran mitigated these effects, downregulating liver enzymes, modulating coagulation factors, restoring eNOS levels, and reducing histopathological and inflammatory markers. Dabigatran demonstrates significant therapeutic potential in alleviating methotrexate-induced hepatotoxicity through its antioxidant, anti-inflammatory, anticoagulant, and anti-apoptotic effects. Its regulation of coagulation parameters and endothelial function suggests a protective role against tissue damage, warranting further investigation.

GLP-1RA-induced delays in gastrointestinal motility: Predicted effects on coadministered drug absorption by PBPK analysis

BACKGROUND

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are breakthrough medicines for obesity treatment and have rapidly gained widespread clinical application. Although GLP-1RAs are generally not associated with drug-drug interactions (DDIs) via drug metabolism or transporter pathways, their effects on reduced gastrointestinal (GI) motility could influence the pharmacokinetics of coadministered oral medications.

OBJECTIVES

This study uses physiologically based pharmacokinetic (PBPK) modeling to evaluate the DDI potential of GLP-1RA-induced GI motility delays.

METHODS

Using Certara's Simcyp™ Simulator V23, we modeled the pharmacokinetics of atorvastatin, metformin, metoprolol, ethinyl estradiol, and digoxin in a virtual cohort of obese adults (n = 1000). GLP-1RA-related gastric emptying delays were simulated based on capsule endoscopy data from liraglutide-treated patients. Results were compared with clinical data from semaglutide and liraglutide users. Additionally, exploratory analyses were conducted on frequently coadministered drugs identified from the 2022 Medical Expenditure Panel Survey, including rosuvastatin and dabigatran.

RESULTS

GLP-1RA-induced gastric emptying delays led to increased area under the concentration-time curve (AUC) and prolonged time to maximum concentration (Tmax) for several medications. The model outputs for rosuvastatin, valsartan, and dabigatran indicate increases in AUC by 64%, 90%, and 205%, respectively. Dabigatran, a narrow therapeutic index anticoagulant, exhibited the most significant changes, raising potential concerns of higher drug exposure.

CONCLUSIONS

PBPK modeling suggests that GLP-1RAs can influence the pharmacokinetics of oral medications by delaying gastric emptying, potentially leading to clinically relevant DDIs. While further clinical validation and pharmacovigilance is needed, these findings highlight the importance of PBPK tools in predicting and potentially mitigating risks associated with GLP-1RA use.

Modifications of the Prothrombin Active Site S4 Subpocket Confer Resistance to Dabigatran

Direct anticoagulants inhibit coagulation serine proteases by reversibly engaging their active site with high affinity. By modifying the S4 active site subpocket of factor (F)Xa, we introduced inhibitor resistance while preserving catalytic activity. Given the homology between FXa and thrombin in active site architecture and direct anticoagulant binding, we have targeted the S4 subsite to introduce inhibitor resistance in (pro)thrombin.Recombinant prothrombin variants were generated in which I174 was substituted or sequence R92-N98 was exchanged with that of human kallikrein-3.Specific prothrombin clotting activity of the variants was 6-fold (intrinsic clotting) to 10-fold (extrinsic clotting) reduced relative to wild-type prothrombin. Further analyses revealed that modification of the S4 subsite hampers fibrinogen and thrombomodulin-mediated protein C conversion by thrombin. Consistent with this, the thrombin variants displayed a reduced catalytic efficiency toward the peptidyl substrate used in thrombin generation assessments. The variants displayed a 2-fold reduced sensitivity for dabigatran relative to wild-type prothrombin, while argatroban inhibition was unaffected. Analyses using a purified component system revealed an up to 24-fold and 4-fold reduced IC50 for inhibition of thrombin by dabigatran and argatroban, respectively. Molecular dynamics (MD) simulations of both dabigatran-bound and unbound (apo) modified thrombin variants indicated these to comprise a larger inhibitor binding pocket relative to wild-type thrombin and display reduced inhibitor binding. As a net effect, (pro)thrombin variants with S4 subsite modifications supported detectable fibrin formation at therapeutic dabigatran concentrations.Our findings provide proof-of-concept for the engineering of thrombin variants that are resistant to direct thrombin inhibitors by modulating the S4 subsite.

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.

SLC4A4, FRAS1, and SULT1A1 Genetic Variations Associated With Dabigatran Metabolism in a Healthy Chinese Population

Background: The purpose of this study was to identify genetic variations associated with the metabolism of dabigatran in healthy Chinese subjects, with particular focus given to pharmacokinetics (PK) and pharmacodynamics (PD).

Methods: Healthy Chinese adults aged 18–65 years with unknown genotypes from a bioequivalence trial were included according to the protocol registered at ClinicalTrial.org (NCT03161496). All subjects received a single dose (150 mg) of dabigatran etexilate. PK (main outcomes: area under the concentration-time, AUC0-t, of total and free dabigatran) and PD (main outcomes: anti-FIIa activity, APTT, and PT) parameters were evaluated. Whole-exome sequencing and genome-wide association analyses were performed. Additionally, candidate gene association analyses related to dabigatran were conducted.

Results: A total of 118 healthy Chinese subjects were enrolled in this study. According to the p-value suggestive threshold (1.0 × 10−4), the following three SNPs were found to be associated with the AUC0–t of total dabigatran: SLC4A4 SNP rs138389345 (p = 5.99 × 10−5), FRAS1 SNP rs6835769 (p = 6.88 × 10−5), and SULT1A1 SNP rs9282862 (p = 7.44 × 10−5). Furthermore, these SNPs were also found to have significant influences on the AUC0–t of free dabigatran, maximum plasma concentration, and anti-FIIa activity (p &lt; 0.05). Moreover, we identified 30 new potential SNPs of 13 reported candidate genes (ABCB1, ABCC2, ABCG2, CYP2B6, CYP1A2, CYP2C19, CYP3A5, CES1, SLCO1B1, SLC22A1, UGT1A1, UGT1A9, and UGT2B7) that were associated with drug metabolism.

Conclusion: Genetic variations were indeed found to impact dabigatran metabolism in a population of healthy Chinese subjects. Further research is needed to explore the more detailed functions of these SNPs. Additionally, our results should be verified in studies that use larger sample sizes and investigate other ethnicities.