Ruth Harper

Dabigatran versus warfarin in patients with mechanical heart valves.

BACKGROUND Dabigatran is an oral direct thrombin inhibitor that has been shown to be an effective alternative to warfarin in patients with atrial fibrillation. We evaluated the use of dabigatran in patients with mechanical heart valves. METHODS In this phase 2 dose-validation study, we studied two populations of patients: those who had undergone aortic- or mitral-valve replacement within the past 7 days and those who had undergone such replacement at least 3 months earlier. Patients were randomly assigned in a 2:1 ratio to receive either dabigatran or warfarin. The selection of the initial dabigatran dose (150, 220, or 300 mg twice daily) was based on kidney function. Doses were adjusted to obtain a trough plasma level of at least 50 ng per milliliter. The warfarin dose was adjusted to obtain an international normalized ratio of 2 to 3 or 2.5 to 3.5 on the basis of thromboembolic risk. The primary end point was the trough plasma level of dabigatran. RESULTS The trial was terminated prematurely after the enrollment of 252 patients because of an excess of thromboembolic and bleeding events among patients in the dabigatran group. In the as-treated analysis, dose adjustment or discontinuation of dabigatran was required in 52 of 162 patients (32%). Ischemic or unspecified stroke occurred in 9 patients (5%) in the dabigatran group and in no patients in the warfarin group; major bleeding occurred in 7 patients (4%) and 2 patients (2%), respectively. All patients with major bleeding had pericardial bleeding. CONCLUSIONS The use of dabigatran in patients with mechanical heart valves was associated with increased rates of thromboembolic and bleeding complications, as compared with warfarin, thus showing no benefit and an excess risk. (Funded by Boehringer Ingelheim; ClinicalTrials.gov numbers, NCT01452347 and NCT01505881.).

Dual Antithrombotic Therapy with Dabigatran after PCI in Atrial Fibrillation

Background Triple antithrombotic therapy with warfarin plus two antiplatelet agents is the standard of care after percutaneous coronary intervention (PCI) for patients with atrial fibrillation, but this therapy is associated with a high risk of bleeding. Methods In this multicenter trial, we randomly assigned 2725 patients with atrial fibrillation who had undergone PCI to triple therapy with warfarin plus a P2Y12 inhibitor (clopidogrel or ticagrelor) and aspirin (for 1 to 3 months) (triple‐therapy group) or dual therapy with dabigatran (110 mg or 150 mg twice daily) plus a P2Y12 inhibitor (clopidogrel or ticagrelor) and no aspirin (110‐mg and 150‐mg dual‐therapy groups). Outside the United States, elderly patients (≥80 years of age; ≥70 years of age in Japan) were randomly assigned to the 110‐mg dual‐therapy group or the triple‐therapy group. The primary end point was a major or clinically relevant nonmajor bleeding event during follow‐up (mean follow‐up, 14 months). The trial also tested for the noninferiority of dual therapy with dabigatran (both doses combined) to triple therapy with warfarin with respect to the incidence of a composite efficacy end point of thromboembolic events (myocardial infarction, stroke, or systemic embolism), death, or unplanned revascularization. Results The incidence of the primary end point was 15.4% in the 110‐mg dual‐therapy group as compared with 26.9% in the triple‐therapy group (hazard ratio, 0.52; 95% confidence interval [CI], 0.42 to 0.63; P<0.001 for noninferiority; P<0.001 for superiority) and 20.2% in the 150‐mg dual‐therapy group as compared with 25.7% in the corresponding triple‐therapy group, which did not include elderly patients outside the United States (hazard ratio, 0.72; 95% CI, 0.58 to 0.88; P<0.001 for noninferiority). The incidence of the composite efficacy end point was 13.7% in the two dual‐therapy groups combined as compared with 13.4% in the triple‐therapy group (hazard ratio, 1.04; 95% CI, 0.84 to 1.29; P=0.005 for noninferiority). The rate of serious adverse events did not differ significantly among the groups. Conclusions Among patients with atrial fibrillation who had undergone PCI, the risk of bleeding was lower among those who received dual therapy with dabigatran and a P2Y12 inhibitor than among those who received triple therapy with warfarin, a P2Y12 inhibitor, and aspirin. Dual therapy was noninferior to triple therapy with respect to the risk of thromboembolic events. (Funded by Boehringer Ingelheim; RE‐DUAL PCI ClinicalTrials.gov number, NCT02164864.)

A comparison of dabigatran etexilate with warfarin in patients with mechanical heart valves: THE Randomized, phase II study to evaluate the safety and pharmacokinetics of oral dabigatran etexilate in patients after heart valve replacement (RE-ALIGN).

BACKGROUND Vitamin K antagonists are the only oral anticoagulants approved for long-term treatment of patients with a cardiac valve replacement. OBJECTIVE This study aims to test a new dosing regimen for dabigatran etexilate in patients with a mechanical bileaflet valve. METHODS Patients aged ≥ 18 years and ≤ 75 years, either undergoing implantation of a mechanical bileaflet valve (aortic or mitral or both) during the current hospital stay or having undergone implantation a mitral bileaflet valve >3 months before randomization, will be randomized between dabigatran etexilate or warfarin (in a ratio of 2:1) in an open-label design. Initial doses of dabigatran will be based on the estimated creatinine clearance, and the doses will be adjusted based on measuring trough dabigatran plasma levels to achieve levels ≥ 50 ng/mL at steady state. Doses will range between 150 mg twice a day and 300 mg twice a day. Warfarin management and target international normalized ratio will be according to current practice guidelines at the discretion of the treating physicians. The plan is to treat 270 patients with dabigatran etexilate for a total study population of approximately 405 patients. Clinical efficacy and safety outcomes will be analyzed in an exploratory manner. CONCLUSIONS RE-ALIGN is the first study to test an alternative to warfarin in patients with mechanical heart valves. A definitive phase III study will be planned based on the results of this study.

Pharmacokinetics, Pharmacodynamics, Safety and Tolerability of Dabigatran Etexilate Oral Liquid Formulation in Infants with Venous Thromboembolism.

Venous thromboembolism (VTE) is more frequent in infants than in older children. Treatment guidelines in children are adapted from adult VTE data, but do not currently include direct oral anticoagulant use. Dabigatran etexilate (DE) use in the paediatric population with VTE therefore requires verification. We investigated the pharmacokinetic/pharmacodynamic (PK/PD) relationship, safety and tolerability of DE oral liquid formulation (OLF) in infants with VTE (aged < 12 months) who had completed standard anticoagulant treatment in an open-label, phase IIa study. Patients received a single-dose of DE OLF (based on an age- and weight-adjusted nomogram) yielding an exposure comparable to 150 mg in adults. The PK end point was plasma concentration of total dabigatran; PD end points included activated partial thromboplastin time (aPTT), ecarin clotting time (ECT) and diluted thrombin time (dTT). Safety end points included incidence of all bleeding and other adverse events (AEs). Ten patients were screened; eight entered the study (age range, 41-169 days). The geometric mean (gMean) total dabigatran plasma concentrations 2 hours post-dose (around peak concentrations) were 120 ng/mL with a geometric coefficient of variation (gCV) of 62.1%. The gMean at 12 hours post-dosing was 60.4 ng/mL (gCV 30%). PK/PD relationship was linear for ECT and dTT (R2 = 0.858 and 0.920, respectively), while total dabigatran concentration and aPTT showed a non-linear correlation. There were no deaths, treatment discontinuations or treatment-related AEs. In conclusion, DE was well tolerated without any treatment-related AEs in infants. The observed PK/PD relationships were comparable with the established profile in older patients with VTE.

Phase IIa study of dabigatran etexilate in children with venous thrombosis: pharmacokinetics, safety, and tolerability

Essentials Dabigatran etexilate may provide a new treatment option for pediatric venous thromboembolism. Children aged 1 to < 12 years were given dabigatran etexilate in an open‐label, single‐arm study. The pharmacokinetic–pharmacodynamic relationship was similar to that seen in adult patients. There were no serious adverse events, bleeding events or recurrent venous thromboembolism.

Design and rationale for the DIVERSITY study: An open-label, randomized study of dabigatran etexilate for pediatric venous thromboembolism

Essentials Current standard of care (SOC) for pediatric venous thromboembolism (VTE) has limitations. Dabigatran etexilate (DE) versus SOC will be studied in children with VTE in a phase IIb/III trial. A dosing algorithm for DE in children will be assessed guiding dosing. Valuable data on the safety and efficacy of DE for VTE in children will be obtained.

Phase 3, single-arm, multicenter study of dabigatran etexilate for secondary prevention of venous thromboembolism in children: Rationale and design

Anticoagulant therapy for venous thromboembolism (VTE) in children is largely based on treatment recommendations for adults. However, differences in both physiology (ie, renal maturation and drug excretion) and developmental hemostasis must be considered when treating children, as such differences could affect dose appropriateness, safety and efficacy.