| Pharmacotherapeutic group: antithrombotic, direct thrombine inhibitors, ATC code: B01AE07. Mechanism of action Dabigatran etexilate is a small molecule prodrug which does not exhibit any pharmacological activity. After oral administration, dabigatran etexilate is rapidly absorbed and converted to dabigatran by esterase-catalysed hydrolysis in plasma and in the liver. Dabigatran is a potent, competitive, reversible direct thrombin inhibitor and is the main active principle in plasma.Since thrombin (serine protease) enables the conversion of fibrinogen into fibrin during the coagulation cascade, its inhibition prevents the development of thrombus. Dabigatran also inhibits free thrombin, fibrin-bound thrombin and thrombin-induced platelet aggregation.Pharmacodynamic effects In-vivo and ex-vivo animal studies have demonstrated antithrombotic efficacy and anticoagulant activity of dabigatran after intravenous administration and of dabigatran etexilate after oral administration in various animal models of thrombosis.There is a clear correlation between plasma dabigatran concentration and degree of anticoagulant effect based on phase II studies. Dabigatran prolongs the thrombin time (TT), ECT, and aPTT.The calibrated diluted TT (dTT) test provides an estimation of dabigatran plasma concentration that can be compared to the expected dabigatran plasma concentrations.The ECT can provide a direct measure of the activity of direct thrombin inhibitors.The aPTT test is widely available and provides an approximate indication of the anticoagulation intensity achieved with dabigatran. However, the aPTT test has limited sensitivity and is not suitable for precise quantification of anticoagulant effect, especially at high plasma concentrations of dabigatran. High aPTT values should be interpreted with caution. In general, it can be assumed that these measures of anti-coagulant activity may reflect dabigatran levels and can provide guidance for the assessment of bleeding risk, i.e. exceeding the 90th percentile of dabigatran trough levels or a coagulation assay such as aPTT measured at trough is considered to be associated with an increased risk of bleeding.Prevention of VTE Steady state (after day 3) geometric mean dabigatran peak plasma concentration, measured around 2 hours after 220 mg dabigatran etexilate administration, was 70.8 ng/mL, with a range of 35.2-162 ng/mL (25th75th percentile range).The dabigatran geometric mean trough concentration, measured at the end of the dosing interval (i.e. 24 hours after a 220 mg dabigatran dose), was on average 22.0 ng/mL, with a range of 13.0-35.7 ng/mL (25th75th percentile range).In patients treated for prevention of VTEs after hip or knee replacement surgery with 220 mg dabigatran etexilate once daily,• the 90th percentile of dabigatran plasma concentrations was 67 ng/mL, measured at trough (20-28 hours after the previous dose) (see section 4.4 and 4.9),• the 90th percentile of aPTT at trough (20-28 hours after the previous dose) was 51 seconds, which would be 1.3-fold upper limit of normal.The ECT was not measured in patients treated for prevention of VTEs after hip or knee replacement surgery with 220 mg dabigatran etexilate once daily.Prevention of stroke and SEE in adult patients with nonvalvular atrial fibrillation with one or more risk factorsSteady state geometric mean dabigatran peak plasma concentration, measured around 2 hours after 150 mg dabigatran etexilate administration twice daily, was 175 ng/mL, with a range of 117-275 ng/mL (25th75th percentile range). The dabigatran geometric mean trough concentration, measured at trough in the morning, at the end of the dosing interval (i.e. 12 hours after the 150 mg dabigatran evening dose), was on average 91.0 ng/mL, with a range of 61.0-143 ng/mL (25th75th percentile range). For patients with atrial nonvalvular fibrillation treated for prevention of stroke and SEE with 150 mg dabigatran etexilate twice daily,• the 90th percentile of dabigatran plasma concentrations measured at trough (10-16 hours after the previous dose) was about 200 ng/mL,• an ECT at trough (10-16 hours after the previous dose), elevated approximately 3-fold upper limit of normal refers to the observed 90th percentile of ECT prolongation of 103 seconds,• an aPTT ratio greater than 2-fold upper limit of normal (aPTT prolongation of about 80 seconds), at trough (10-16 hours after the previous dose) reflects the 90th percentile of observations.Clinical efficacy and safety Ethnic origin No clinically relevant ethnic differences among Caucasians, African-American, Hispanic, Japanese or Chinese patients were observed.Clinical trials in Venous Thromboembolism (VTE) prophylaxis following major joint replacement surgery In 2 large randomized, parallel group, double-blind, doseconfirmatory trials, patients undergoing elective major orthopaedic surgery (one for knee replacement surgery and one for hip replacement surgery) received Pradaxa 75 mg or 110 mg within 1-4 hours of surgery followed by 150 mg or 220 mg once daily thereafter, haemostasis having been secured, or enoxaparin 40 mg on the day prior to surgery and daily thereafter.In the RE-MODEL trial (knee replacement) treatment was for 6-10 days and in the RE-NOVATE trial (hip replacement) for 28-35 days. Totals of 2,076 patients (knee) and 3,494 (hip) were treated respectively.Composite of total VTE (including PE, proximal and distal DVT, whatever symptomatic or asymptomatic detected by routine venography) and all-cause mortality constituted the primary end-point for both studies. Composite of major VTE (including PE and proximal DVT, whatever symptomatic or asymptomatic detected by routine venography) and VTE-related mortality constituted a secondary end-point and is considered of better clinical relevance.Results of both studies showed that the antithrombotic effect of Pradaxa 220 mg and 150 mg were statistically non-inferior to that of enoxaparin on total VTE and all-cause mortality. The point estimate for incidence of Major VTE and VTE related mortality for the 150 mg dose was slightly worse than enoxaparin (table 7). Better results were seen with the 220 mg dose where the point estimate of Major VTE was slightly better than enoxaparin (table 7).The clinical studies have been conducted in a patient population with a mean age > 65 years.There were no differences in the phase 3 clinical studies for efficacy and safety data between men and women.In the studied patient population of RE-MODEL and RE-NOVATE (5,539 patients treated), 51 % suffered from concomitant hypertension, 9 % from concomitant diabetes, 9 % from concomitant coronary artery disease and 20 % had a history of venous insufficiency. None of these diseases showed an impact on the effects of dabigatran on VTE-prevention or bleeding rates.Data for the major VTE and VTE-related mortality endpoint were homogeneous with regards to the primary efficacy endpoint and are shown in table 7.Data for the total VTE and all cause mortality endpoint are shown in table 8.Data for adjudicated major bleeding endpoints are shown in table 9 below.Table 7: Analysis of major VTE and VTE-related mortality during the treatment period in the RE-MODEL and the RE-NOVATE orthopaedic surgery studies.| Trial
| Dabigatran etexilate 220 mg once daily
| Dabigatran etexilate 150 mg once daily
| Enoxaparin 40 mg
| | RE-NOVATE (hip)
| | N
| 909
| 888
| 917
| | Incidences (%)
| 28 (3.1)
| 38 (4.3)
| 36 (3.9)
| | Risk ratio over enoxaparin
| 0.78
| 1.09
| | | 95 % CI
| 0.48, 1.27
| 0.70, 1.70
| | | RE-MODEL (knee)
| | N
| 506
| 527
| 511
| | Incidences (%)
| 13 (2.6)
| 20 (3.8)
| 18 (3.5)
| | Risk ratio over enoxaparin
| 0.73
| 1.08
| | | 95 % CI
| 0.36, 1.47
| 0.58, 2.01
| | Table 8: Analysis of total VTE and all cause mortality during the treatment period in the RE-NOVATE and the RE-MODEL orthopaedic surgery studies.| Trial
| Dabigatran etexilate 220 mg once daily
| Dabigatran etexilate 150 mg once daily
| Enoxaparin 40 mg
| | RE-NOVATE (hip)
| | N
| 880
| 874
| 897
| | Incidences (%)
| 53 (6.0)
| 75 (8.6)
| 60 (6.7)
| | Risk ratio over enoxaparin
| 0.9
| 1.28
| | | 95 % CI
| (0.63, 1.29)
| (0.93, 1.78)
| | | RE-MODEL (knee)
| | N
| 503
| 526
| 512
| | Incidences (%)
| 183 (36.4)
| 213 (40.5)
| 193 (37.7)
| | Risk ratio over enoxaparin
| 0.97
| 1.07
| | | 95 % CI
| (0.82, 1.13)
| (0.92, 1.25)
| | Table 9: Major bleeding events by treatment in the individual RE-MODEL and the RE-NOVATE studies.| Trial
| Dabigatran etexilate 220 mg once daily
| Dabigatran etexilate 150 mg once daily
| Enoxaparin 40 mg
| | RE-NOVATE (hip)
| | Treated patients N
| 1,146
| 1,163
| 1,154
| | Number of MBE N(%)
| 23 (2.0)
| 15 (1.3)
| 18 (1.6)
| | RE-MODEL (knee)
| | Treated patients N
| 679
| 703
| 694
| | Number of MBE N(%)
| 10 (1.5)
| 9 (1.3)
| 9 (1.3)
|
Prevention of stroke and SEE in adult patients with nonvalvular atrial fibrillation with one or more risk factors The clinical evidence for the efficacy of dabigatran etexilate is derived from the RE-LY study (Randomized Evaluation of Longterm anticoagulant therapy) a multi-centre, multi-national, randomized parallel group study of two blinded doses of dabigatran etexilate (110 mg and 150 mg twice daily) compared to open-label warfarin in patients with atrial fibrillation at moderate to high risk of stroke and SEE. The primary objective in this study was to determine if dabigatran etexilate was non-inferior to warfarin in reducing the occurrence of the composite endpoint stroke and SEE. Statistical superiority was also analyzed.In the RE-LY study, a total of 18,113 patients were randomized, with a mean age of 71.5 years and a mean CHADS2 score of 2.1. The patient population was 64 % male, 70 % Caucasian and 16 % Asian. For patients randomized to warfarin, the mean percentage of time in therapeutic range (TTR) (INR 2-3) was 64.4 % (median TTR 67 %).The RE-LY study demonstrated that dabigatran etexilate, at a dose of 110 mg twice daily, is non-inferior to warfarin in the prevention of stroke and SEE in subjects with atrial fibrillation, with a reduced risk of ICH, total bleeding and major bleeding. The dose of 150 mg twice daily reduces significantly the risk of ischemic and haemorrhagic stroke, vascular death, ICH and total bleeding compared to warfarin. Major bleeding rates with this dose were comparable to warfarin. Myocardial infarction rates were slightly increased with dabigatran etexilate 110 mg twice daily and 150 mg twice daily compared to warfarin (hazard ratio 1.29; p=0.0929 and hazard ratio 1.27; p=0.1240, respectively). With improving monitoring of INR the observed benefits of dabigatran etexilate compared to warfarin diminish.Tables 10-12 display details of key results in the overall population:Table 10: Analysis of first occurrence of stroke or SEE (primary endpoint) during the study period in RE-LY.| | Dabigatran etexilate 110 mg twice daily
| Dabigatran etexilate 150 mg twice daily
| Warfarin
| | Subjects randomized
| 6,015
| 6,076
| 6,022
| | Stroke and/or SEE
| | | | | Incidences (%)
| 183 (1.54)
| 134 (1.11)
| 202 (1.71)
| | Hazard ratio over warfarin (95 % CI)
| 0.90 (0.74, 1.10)
| 0.65 (0.52, 0.81)
| | | p value superiority
| p=0.2943
| p=0.0001
| | % refers to yearly event rate Table 11: Analysis of first occurrence of ischemic or haemorrhagic strokes during the study period in RE-LY.| | Dabigatran etexilate 110 mg twice daily
| Dabigatran etexilate 150 mg twice daily
| Warfarin
| | Subjects randomized
| 6,015
| 6,076
| 6,022
| | Stroke
| | | | | Incidences (%)
| 171 (1.44)
| 122 (1.01)
| 186 (1.58)
| | Hazard ratio vs. warfarin (95 % CI)
| 0.91 (0.74, 1.12)
| 0.64 (0.51, 0.81)
| | | p-value
| 0.3828
| 0.0001
| | | SEE
| | | | | Incidences (%)
| 15 (0.13)
| 13 (0.11)
| 21 (0.18)
| | Hazard ratio vs. warfarin (95 % CI)
| 0.71 (0.37, 1.38)
| 0.61 (0.30, 1.21)
| | | p-value
| 0.3099
| 0.1582
| | | Ischemic stroke
| | | | | Incidences (%)
| 152 (1.28)
| 103 (0.86)
| 134 (1.14)
| | Hazard ratio vs. warfarin (95 % CI)
| 1.13 (0.89, 1.42)
| 0.75 (0.58, 0.97)
| | | p-value
| 0.3139
| 0.0296
| | | Haemorrhagic stroke
| | | | | Incidences (%)
| 14 (0.12)
| 12 (0.10)
| 45 (0.38)
| | Hazard ratio vs. warfarin (95 % CI)
| 0.31 (0.17, 0.56)
| 0.26 (0.14, 0.49)
| | | p-value
| < 0.001
| < 0.001
| | % refers to yearly event rate Table 12: Analysis of all cause and cardiovascular survival during the study period in RE-LY.| | Dabigatran etexilate 110 mg twice daily
| Dabigatran etexilate 150 mg twice daily
| Warfarin
| | Subjects randomized
| 6,015
| 6,076
| 6,022
| | All-cause mortality
| | | | | Incidences (%)
| 446 (3.75)
| 438 (3.64)
| 487 (4.13)
| | Hazard ratio vs. warfarin (95 % CI)
| 0.91 (0.80, 1.03)
| 0.88 (0.77, 1.00)
| | | p-value
| 0.1308
| 0.0517
| | | Vascular mortality
| | | | | Incidences (%)
| 289 (2.43)
| 274 (2.28)
| 317 (2.69)
| | Hazard ratio vs. warfarin (95 % CI)
| 0.90 (0.77, 1.06)
| 0.85 (0.72, 0.99)
| | | p-value
| 0.2081
| 0.0430
| | % refers to yearly event rate Tables 13-14 display results of the primary efficacy and safety endpoint in relevant sub-populations:For the primary endpoint, stroke and SEE, no subgroups (i.e., age, weight, gender, renal function, ethnicity, etc.) were identified with a different risk ratio compared to warfarin.Table 13: Hazard Ratio and 95 % CI for stroke/SEE by subgroups| Endpoint
| Dabigatran etexilate
110 mg twice daily vs. warfarin
| Dabigatran etexilate
150 mg twice daily vs. warfarin
| | Age (years)
| | | | < 65
| 1.10 (0.64, 1.87)
| 0.51 (0.26, 0.98)
| | 65 ≤ and < 75
| 0.87 (0.62, 1.20)
| 0.68 (0.47, 0.96)
| | ≥ 75
| 0.88 (0.66, 1.17)
| 0.67 (0.49, 0.90)
| | ≥ 80
| 0.68 (0.44, 1.05)
| 0.65 (0.43, 1.00)
| | CrCL (mL/min)
| | | | 30 ≤ and < 50
| 0.89 (0.61, 1.31)
| 0.47 (0.30, 0.74)
| | 50 ≤ and < 80
| 0.91 (0.68, 1.20)
| 0.65 (0.47, 0.88)
| | ≥ 80
| 0.83 (0.52, 1.32)
| 0.71 (0.44, 1.15)
| For the primary safety endpoint of major bleeding there was an interaction of treatment effect and age. The relative risk of bleeding with dabigatran compared to warfarin increased with age. Relative risk was highest in patients ≥ 75 years. The concomitant use of antiplatelets ASA or clopidogrel approximately doubles MBE rates with both dabigatran etexilate and warfarin. There was no significant interaction of treatment effects with the subgroups of renal function and CHADS2 score.Table 14: Hazard Ratio and 95 % CI for major bleeds by subgroups| Endpoint
| Dabigatran etexilate
110 mg twice daily vs. warfarin
| Dabigatran etexilate
150 mg twice daily vs. warfarin
| | Age (years)
| | | | < 65
| 0.33 (0.19, 0.59)
| 0.36 (0.21, 0.62)
| | 65 ≤ and < 75
| 0.70 (0.56, 0.89)
| 0.80 (0.64, 1.00)
| | ≥ 75
| 1.01 (0.83, 1.23)
| 1.18 (0.98, 1.43)
| | ≥ 80
| 1.12 (0.84, 1.49)
| 1.35 (1.03, 1.77)
| | CrCL (mL/min)
| | | | 30 ≤ and < 50
| 1.00 (0.77, 1.29)
| 0.94 (0.72, 1.21)
| | 50 ≤ and < 80
| 0.76 (0.61, 0.93)
| 0.89 (0.73, 1.08)
| | ≥ 80
| 0.59 (0.43, 0.82)
| 0.84 (0.62, 1.13)
| | ASA use
| 0.85 (0.68, 1.05)
| 0.92 (0.75, 1.14)
| | Clopidogrel use
| 0.88 (0.56, 1.37)
| 0.95 (0.62, 1.46)
|
Paediatric population The European Medicines Agency has waived the obligation to submit the results of studies with Pradaxa in all subsets of the paediatric population in prevention of thromboembolic events in the granted indication (see section 4.2 for information on paediatric use).Clinical trials for the prevention of thromboembolism in patients with prosthetic heart valvesA phase II study examined dabigatran etexilate and warfarin in a total of 252 patients with recent mechanical valve replacement surgery (i.e. within the current hospital stay) and in patients who received a mechanical heart valve replacement more than three months ago. More thromboembolic events (mainly strokes and symptomatic/asymptomatic prosthetic valve thrombosis) and more bleeding events were observed with dabigatran etexilate than with warfarin. In the early post-operative patients, major bleeding manifested predominantly as haemorrhagic pericardial effusions, specifically in patients who started dabigatran etexilate early (i.e. on Day 3) after heart valve replacement surgery (see section 4.3). | |