Pradaxa (Dabigatran Etexilate Mesylate) doses beyond those recommended expose the patient to increased risk of bleeding.
In case of an overdose suspicion, coagulation tests can help to determine a bleeding risk. A calibrated quantitative dTT test or repetitive dTT measurements allow prediction of the time by when certain dabigatran levels will be reached , also in case additional measures e.g. dialysis have been initiated.
Excessive anticoagulation may require interruption of Pradaxa (Dabigatran Etexilate Mesylate) treatment. Since dabigatran is excreted predominantly by the renal route adequate diuresis must be maintained. As protein binding is low, dabigatran can be dialysed; there is limited clinical experience to demonstrate the utility of this approach in clinical studies.
Management of bleeding complications
In the event of haemorrhagic complications, Pradaxa (Dabigatran Etexilate Mesylate) treatment must be discontinued and the source of bleeding investigated. Depending on the clinical situation appropriate supportive treatment, such as surgical haemostasis and blood volume replacement, should be undertaken at the prescribers discretion.
For situations when rapid reversal of the anticoagulant effect of Pradaxa (Dabigatran Etexilate Mesylate) is required the specific reversal agent (Praxbind, idarucizumab) antagonizing the pharmacodynamic effect of Pradaxa (Dabigatran Etexilate Mesylate) is available.
Coagulation factor concentrates (activated or non-activated) or recombinant Factor VIIa may be taken into account. There is some experimental evidence to support the role of these medicinal products in reversing the anticoagulant effect of dabigatran, but data on their usefulness in clinical settings and also on the possible risk of rebound thromboembolism is very limited. Coagulation tests may become unreliable following administration of suggested coagulation factor concentrates. Caution should be exercised when interpreting these tests. Consideration should also be given to administration of platelet concentrates in cases where thrombocytopenia is present or long acting antiplatelet medicinal products have been used. All symptomatic treatment should be given according to the physician's judgement.
Depending on local availability, a consultation of a coagulation expert should be considered in case of major bleedings.
-
- Patients with severe renal impairment (CrCL < 30 mL/min)
- Active clinically significant bleeding
- Lesion or condition, if considered a significant risk factor for major bleeding. This may include current or recent gastrointestinal ulceration, presence of malignant neoplasms at high risk of bleeding, recent brain or spinal injury, recent brain, spinal or ophthalmic surgery, recent intracranial haemorrhage, known or suspected oesophageal varices, arteriovenous malformations, vascular aneurysms or major intraspinal or intracerebral vascular abnormalities
- Concomitant treatment with any other anticoagulants e.g. unfractionated heparin (UFH), low molecular weight heparins (enoxaparin, dalteparin etc), heparin derivatives (fondaparinux etc), oral anticoagulants (warfarin, rivaroxaban, apixaban etc) except under specific circumstances. These are switching anticoagulant therapy , when UFH is given at doses necessary to maintain an open central venous or arterial catheter or when UFH is given during catheter ablation for atrial fibrillation
- Hepatic impairment or liver disease expected to have any impact on survival
- Concomitant treatment with the following strong P-gp inhibitors: systemic ketoconazole, cyclosporine, itraconazole and dronedarone
- Prosthetic heart valves requiring anticoagulant treatment .
Not applicable.
Summary of the safety profile
The safety of Pradaxa (Dabigatran Etexilate Mesylate) has been evaluated in ten phase III studies including 23,393 patients exposed to Pradaxa (Dabigatran Etexilate Mesylate) (see Table 10).
Table 10: Number of patients studied, maximum daily dose in phase III studies
| Indication | Number of patients treated with Pradaxa (Dabigatran Etexilate Mesylate) | Maximum daily dose |
| Primary Prevention of Venous Thromboembolism in Orthopaedic Surgery | 6,684 | 220 mg |
| Stroke and systemic embolism prevention in patients with atrial fibrillation | 6,059 5,983 | 300 mg 220 mg |
| DVT/PE treatment (RE-COVER, RE-COVER II) | 2,553 | 300 mg |
| DVT/PE prevention (RE-MEDY, RE-SONATE) | 2,114 | 300 mg |
In total, about 9 % of patients treated for elective hip or knee surgery (short-term treatment for up to 42 days) , 22 % of patient with atrial fibrillation treated for the prevention of stroke and systemic embolism (long-term treatment for up to 3 years), 14 % of patient treated for DVT/PE and 15 % of patients treated for DVT/PE prevention experienced adverse reactions.
The most commonly reported events are bleedings occurring in approximately 14 % of patients treated short-term for elective hip or knee replacement surgery, 16.6 % in patients with atrial fibrillation treated long-term for the prevention of stroke and systemic embolism, and in 14.4 % of patients treated for DVT/PE. Furthermore, bleeding occurred in 19.4% of patients in the DVT/PE prevention trial RE-MEDY and in 10.5% of patient in the DVT/PE prevention trial RE-SONATE.
Since the patient populations treated in the three indications are not comparable and bleeding events are distributed over several System Organ Classes (SOC), a summary description of major and any bleeding are broken down by indication and given in tables 12-16 below.
Although low in frequency in clinical trials, major or severe bleeding may occur and, regardless of location, may lead to disabling, life-threatening or even fatal outcomes.
Tabulated list of adverse reactions
Table 11 shows the adverse reactions identified from the primary VTE prevention studies after hip or knee replacement surgery, the study in the prevention of thromboembolic stroke , and systemic embolism in patients with atrial fibrillation and the studies in DVT/PE treatment and in DVT/PE prevention. They are ranked under headings of SOC and frequency using the following convention: very common (> 1/10), common (> 1/100 to < 1/10), uncommon (> 1/1,000 to < 1/100), rare (> 1/10,000 to < 1/1,000), very rare (< 1/10,000), not known (cannot be estimated from the available data).
Table 11: Adverse reactions
| Frequency | |||
| SOC / Preferred term. | Primary VTE prevention after hip or knee replacement surgery | Stroke and systemic embolism prevention in patients with atrial fibrillation | DVT/PE treatment and DVT/PE prevention |
| Blood and lymphatic system disorders | |||
| Anaemia | Uncommon | Common | Uncommon |
| Haemoglobin decreased | Common | Uncommon | Not known |
| Thrombocytopenia | Rare | Uncommon | Rare |
| Haematocrit decreased | Uncommon | Rare | Not known |
| Immune system disorder | |||
| Drug hypersensitivity | Uncommon | Uncommon | Uncommon |
| Rash | Rare | Uncommon | Uncommon |
| Pruritus | Rare | Uncommon | Uncommon |
| Anaphylactic reaction | Rare | Rare | Rare |
| Angioedema | Rare | Rare | Rare |
| Urticaria | Rare | Rare | Rare |
| Bronchospasm | Not known | Not known | Not known |
| Nervous system disorders | |||
| Intracranial haemorrhage | Rare | Uncommon | Rare |
| Vascular disorders | |||
| Haematoma | Uncommon | Uncommon | Uncommon |
| Haemorrhage | Rare | Uncommon | Uncommon |
| Wound haemorrhage | Uncommon | - |
|
| Respiratory, thoracic and mediastinal disorders | |||
| Epistaxis | Uncommon | Common | Common |
| Haemoptysis | Rare | Uncommon | Uncommon |
| Gastrointestinal disorders | |||
| Gastrointestinal haemorrhage | Uncommon | Common | Common |
| Abdominal pain | Rare | Common | Uncommon |
| Diarrhoea | Uncommon | Common | Uncommon |
| Dyspepsia | Rare | Common | Common |
| Nausea | Uncommon | Common | Uncommon |
| Rectal haemorrhage | Uncommon | Uncommon | Common |
| Haemorrhoidal haemorrhage | Uncommon | Uncommon | Uncommon |
| Gastrointestinal ulcer, including oesophageal ulcer | Rare | Uncommon | Uncommon |
| Gastroesophagitis | Rare | Uncommon | Uncommon |
| Gastroesophageal reflux disease | Rare | Uncommon | Uncommon |
| Vomiting | Uncommon | Uncommon | Uncommon |
| Dysphagia | Rare | Uncommon | Rare |
| Hepatobiliary disorders | |||
| Hepatic function abnormal/ Liver function Test abnormal | Common | Uncommon | Uncommon |
| Alanine aminotransferase increased | Uncommon | Uncommon | Uncrommon |
| Aspartate aminotransferase increased | Uncommon | Uncommon | Uncommon |
| Hepatic enzyme increased | Uncommon | Rare | Uncommon |
| Hyperbilirubinaemia | Uncommon | Rare | Not known |
| Skin and subcutaneous tissue disorder | |||
| Skin haemorrhage | Uncommon | Common | Common |
| Musculoskeletal and connective tissue disorders | |||
| Haemarthrosis | Uncommon | Rare | Uncommon |
| Renal and urinary disorders | |||
| Genitourological haemorrhage, including haematuria | Uncommon | Common | Common |
| General disorders and administration site conditions | |||
| Injection site haemorrhage | Rare | Rare | Rare |
| Catheter site haemorrhage | Rare | Rare | Rare |
| Bloody discharge | Rare | - |
|
| Injury, poisoning and procedural complications | |||
| Traumatic haemorrhage | Uncommon | Rare | Uncommon |
| Incision site haemorrhage | Rare | Rare | Rare |
| Post procedural haematoma | Uncommon | - | - |
| Post procedural haemorrhage | Uncommon | - |
|
| Anaemia postoperative | Rare | - | - |
| Post procedural discharge | Uncommon | - | - |
| Wound secretion | Uncommon | - | - |
| Surgical and medical procedures | |||
| Wound drainage | Rare | - | - |
| Post procedural drainage | Rare | - | . |
Description of selected adverse reactions
Bleeding reactions
Due to the pharmacological mode of action, the use of Pradaxa (Dabigatran Etexilate Mesylate) may be associated with an increased risk of occult or overt bleeding from any tissue or organ. The signs, symptoms, and severity (including fatal outcome) will vary according to the location and degree or extent of the bleeding and/or anaemia. In the clinical studies mucosal bleedings (e.g. gastrointestinal, genitourinary) were seen more frequently during long term Pradaxa (Dabigatran Etexilate Mesylate) treatment compared with VKA treatment. Thus, in addition to adequate clinical surveillance, laboratory testing of haemoglobin/haematocrit is of value to detect occult bleeding. The risk of bleedings may be increased in certain patient groups e.g. those patients with moderate renal impairment and/or on concomitant treatment affecting haemostasis or strong P-gp inhibitors. Haemorrhagic complications may present as weakness, paleness, dizziness, headache or unexplained swelling, dyspnoea, and unexplained shock.
Known bleeding complications such as compartment syndrome and acute renal failure due to hypoperfusion have been reported for Pradaxa (Dabigatran Etexilate Mesylate). Therefore, the possibility of haemorrhage is to be considered in evaluating the condition in any anticoagulated patient. A specific reversal agent for dabigatran, idarucizumab, is available in case of uncontrollable bleeding.
Primary Prevention of Venous Thromboembolism in Orthopaedic Surgery
The table 12 shows the number (%) of patients experiencing the adverse reaction bleeding during the treatment period in the VTE prevention in the two pivotal clinical trials, according to dose.
Table 12: Number (%) of patients experiencing the adverse reaction bleeding
| Pradaxa (Dabigatran Etexilate Mesylate) 150 mg once daily N (%) | Pradaxa (Dabigatran Etexilate Mesylate) 220 mg once daily N (%) | Enoxaparin
N (%) | |
| Treated | 1,866 (100.0) | 1,825 (100.0) | 1,848 (100.0) |
| Major bleeding | 24 (1.3) | 33 (1.8) | 27 (1.5) |
| Any bleeding | 258 (13.8) | 251 (13.8) | 247 (13.4) |
Prevention of stroke and systemic embolism in adult patients with NVAF with one or more risk factors
The table 13 shows bleeding events broken down to major and any bleeding in the pivotal study testing the prevention of thromboembolic stroke and systemic embolism in patients with atrial fibrillation.
Table 13: Bleeding events in a study testing the prevention of thromboembolic stroke and systemic embolism in patients with atrial fibrillation
|
| Pradaxa (Dabigatran Etexilate Mesylate) 110 mg twice daily | Pradaxa (Dabigatran Etexilate Mesylate) 150 mg twice daily | Warfarin |
| Subjects randomized | 6,015 | 6,076 | 6,022 |
| Major bleeding | 347 (2.92 %) | 409 (3.40 %) | 426 (3.61 %) |
| Intracranial bleeding | 27 (0.23 %) | 39 (0.32 %) | 91 (0.77 %) |
| GI bleeding | 134 (1.13 %) | 192 (1.60 %) | 128 (1.09 %) |
| Fatal bleeding | 26 (0.22 %) | 30 (0.25 %) | 42 (0.36 %) |
| Minor bleeding | 1,566 (13.16 %) | 1,787 (14.85 %) | 1,931 (16.37 %) |
| Any bleeding | 1,759 (14.78 %) | 1,997 (16.60 %) | 2,169 (18.39 %) |
Subjects randomized to Pradaxa (Dabigatran Etexilate Mesylate) 110 mg twice daily or 150 mg twice daily had a significantly lower risk for life-threatening bleeds and intracranial bleeding compared to warfarin [p < 0.05]. Both dose strengths of Pradaxa (Dabigatran Etexilate Mesylate) had also a statistically significant lower total bleed rate. Subjects randomized to 110 mg Pradaxa (Dabigatran Etexilate Mesylate) twice daily had a significantly lower risk for major bleeds compared with warfarin (hazard ratio 0.81 [p=0.0027]). Subjects randomized to 150 mg Pradaxa (Dabigatran Etexilate Mesylate) twice daily had a significantly higher risk for major GI bleeds compared with warfarin (hazard ratio 1.48 [p=0.0005]. This effect was seen primarily in patients > 75 years.
The clinical benefit of dabigatran with regard to stroke and systemic embolism prevention and decreased risk of ICH compared to warfarin is preserved across individual subgroups, e.g. renal impairment, age, concomitant medicinal product use such as anti-platelets or P-gp inhibitors. While certain patient subgroups are at an increased risk of major bleeding when treated with an anticoagulant, the excess bleeding risk for dabigatran is due to GI bleeding, typically seen within the first 3-6 months following initiation of Pradaxa (Dabigatran Etexilate Mesylate) therapy.
Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), and prevention of recurrent DVT and PE in adults (DVT/PE treatment)
Table 14 shows bleeding events in the pooled pivotal studies RE-COVER and RE-COVER II testing the treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE). In the pooled studies the primary safety endpoints of major bleeding, major or clinically relevant bleeding and any bleeding were significantly lower than warfarin at a nominal alpha level of 5 %.
Table 14: Bleeding events in the studies RE-COVER and RE-COVER II testing the treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE)
|
| Pradaxa (Dabigatran Etexilate Mesylate) 150 mg twice daily | Warfarin | Hazard ratio vs. warfarin (95% confidence interval) |
| Patients included in safety analysis | 2,456 | 2,462 |
|
| Major bleeding events | 24 (1.0 %) | 40 (1.6 %) | 0.60 (0.36, 0.99) |
| Intracranial Bleeding | 2 (0.1 %) | 4 (0.2 %) | 0.50 (0.09, 2.74) |
| Major GI bleeding | 10 (0.4 %) | 12 (0.5 %) | 0.83 (0.36, 1.93) |
| Life-threatening bleed | 4 (0.2 %) | 6 (0.2 %) | 0.66 (0.19, 2.36) |
| Major bleeding events/clinically relevant bleeds | 109 (4.4 %) | 189 (7.7 %) | 0.56 (0.45, 0.71) |
| Any bleeding | 354 (14.4 %) | 503 (20.4 %) | 0.67 (0.59, 0.77) |
| Any GI bleeding | 70 (2.9 %) | 55 (2.2 %) | 1.27 (0.90, 1.82) |
Bleeding events for both treatments are counted from the first intake of Pradaxa (Dabigatran Etexilate Mesylate) or warfarin after the parenteral therapy has been discontinued (oral only treatment period). This includes all bleeding events, which occurred during Pradaxa (Dabigatran Etexilate Mesylate) therapy. All bleeding events which occurred during warfarin therapy are included except for those during the overlap period between warfarin and parenteral therapy.
Table 15 shows bleeding events in pivotal study RE-MEDY testing prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE). Some bleeding events (MBEs/CRBEs; any bleeding) were significantly lower at a nominal alpha level of 5% in patients receiving Pradaxa (Dabigatran Etexilate Mesylate) as compared with those receiving warfarin.
Table 15: Bleeding events in study RE-MEDY testing prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE)
| Pradaxa (Dabigatran Etexilate Mesylate) 150 mg twice daily | Warfarin | Hazard ratio vs warfarin (95% Confidence Interval) | |
| Treated patients | 1,430 | 1,426 |
|
| Major bleeding events | 13 (0.9 %) | 25 (1.8 %) | 0.54 (0.25, 1.16) |
| Intracranial bleeding | 2 (0.1 %) | 4 (0.3 %) | Not calculable* |
| Major GI bleeding | 4 (0.3%) | 8 (0.5%) | Not calculable* |
| Life-threatening bleed | 1 (0.1 %) | 3 (0.2 %)) | Not calculable* |
| Major bleeding event /clinically relevant bleeds | 80 (5.6 %) | 145 (10.2 %) | 0.55 ( 0.41, 0.72)
|
| Any bleeding | 278 (19.4 %) | 373 (26.2 %) | 0.71 (0.61, 0.83) |
| Any GI bleeds | 45 (3.1%) | 32 (2.2%) | 1.39 (0.87, 2.20) |
*HR not estimable as there is no event in either one cohort/treatment
Table 16 shows bleeding events in pivotal study RE-SONATE testing prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE). The rate of the combination of MBEs/CRBEs and the rate of any bleeding was significantly lower at a nominal alpha level of 5 % in patients receiving placebo as compared with those receiving Pradaxa (Dabigatran Etexilate Mesylate).
Table 16: Bleeding events in study RE-SONATE testing prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE)
| Pradaxa (Dabigatran Etexilate Mesylate) 150 mg twice daily | Placebo | Hazard ratio vs placebo (95% confidence interval) | |
| Treated patients | 684 | 659 |
|
| Major bleeding events | 2 (0.3 %) | 0 | Not calculable* |
| Intracranial bleeding | 0 | 0 | Not calculable* |
| Major GI bleeding | 2 (0.3%) | 0 | Not calculable* |
| Life-threatening bleeds | 0 | 0 | Not calculable* |
| Major bleeding event/clinical relevant bleeds | 36 (5.3 %) | 13 (2.0 %) | 2.69 (1.43, 5.07) |
| Any bleeding | 72 (10.5 %) | 40 (6.1 %) | 1.77 (1.20, 2.61) |
| Any GI bleeds | 5 (0.7%) | 2 (0.3%) | 2.38 (0.46, 12.27) |
*HR not estimable as there is no event in either one treatment
Paediatric population (DVT/PE)
In the clinical study 1160.88 in total, 9 adolescent patients (age 12 to < 18 years) with diagnosis of primary VTE received an initial oral dose of dabigatran etexilate of 1.71 (± 10 %) mg/kg bodyweight. Based on dabigatran concentrations as determined by the diluted thrombin time test and clinical assessment, the dose was adjusted to the target dose of 2.14 (± 10%) mg/kg bodyweight of dabigatran etexilate. On treatment 2 (22.1 %) patients experienced mild related adverse events (gastrooesophageal reflux / abdominal pain; abdominal discomfort) and 1 (11.1 %) patient experienced a not related serious adverse event (recurrent VTE of the leg) in the post treatment period > 3 days after stop of dabigatran etexilate.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows c
Non-clinical data reveal no special hazard for humans based on conventional studies of safety pharmacology, repeated dose toxicity and genotoxicity.
Effects observed in the repeated dose toxicity studies were due to the exaggerated pharmacodynamic effect of dabigatran.
An effect on female fertility was observed in the form of a decrease in implantations and an increase in pre-implantation loss at 70 mg/kg (5-fold the plasma exposure level in patients). At doses that were toxic to the mothers (5- to 10-fold the plasma exposure level in patients), a decrease in foetal body weight and viability along with an increase in foetal variations were observed in rats and rabbits. In the pre- and post-natal study, an increase in foetal mortality was observed at doses that were toxic to the dams (a dose corresponding to a plasma exposure level 4-fold higher than observed in patients).
In lifetime toxicology studies in rats and mice, there was no evidence for a tumorigenic potential of dabigatran up to maximum doses of 200 mg/kg.
Dabigatran, the active moiety of dabigatran etexilate mesilate, is persistent in the environment.
Primary prevention of venous thromboembolic events in adult patients who have undergone elective total hip replacement surgery or total knee replacement surgery.
Prevention of stroke and systemic embolism in adult patients with non-valvular atrial fibrillation (NVAF), with one or more risk factors, such as prior stroke or transient ischemic attack (TIA); age > 75 years; heart failure (NYHA Class > II); diabetes mellitus; hypertension.
Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), and prevention of recurrent DVT and PE in adults
Pharmacotherapeutic group: antithrombotic agents, direct thrombin 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 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 quantitative diluted TT (dTT) test provides an estimation of dabigatran plasma concentration that can be compared to the expected dabigatran plasma concentrations. When the calibrated dTT assay delivers a dabigatran plasma concentration result at or below the limit of quantification, an additional coagulation assay such as TT, ECT or aPTT should be considered.
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. Although high aPTT values should be interpreted with caution, a high aPTT value indicates that the patient is anticoagulated.
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.
Primary Prevention of Venous Thromboembolism in Orthopaedic Surgery
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 (25th-75th 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 (25th-75th percentile range).
In a dedicated study exclusively in patients with moderate renal impairment (creatinine clearance, CrCL 30-50 mL/min) treated with dabigatran etexilate 150 mg QD, the dabigatran geometric mean trough concentration, measured at the end of the dosing interval, was on average 47.5 ng/mL, with a range of 29.6 - 72.2 ng/mL (25th-75th 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) ,
- 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 systemic embolism in adult patients with NVAF with one or more risk factors (SPAF)
Steady 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 (25th-75th 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 (25th-75th percentile range).
For patients with NVAF treated for prevention of stroke and systemic embolism 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.
Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), and prevention of recurrent DVT and PE in adults (DVT/PE)
In patients treated for DVT and PE with 150 mg dabigatran etexilate twice daily, the dabigatran geometric mean trough concentration, measured within 10−16 hours after dose, at the end of the dosing interval (i.e. 12 hours after the 150 mg dabigatran evening dose), was 59.7 ng/ml, with a range of 38.6 - 94.5 ng/ml (25th-75th percentile range). For treatment of DVT and PE, with dabigatran etexilate 150 mg twice daily,
- the 90th percentile of dabigatran plasma concentrations measured at trough (10-16 hours after the previous dose) was about 146 ng/ml,
- an ECT at trough (10-16 hours after the previous dose), elevated approximately 2.3-fold compared to baseline refers to the observed 90th percentile of ECT prolongation of 74 seconds,
- the 90th percentile of aPTT at trough (10-16 hours after the previous dose) was 62 seconds, which would be 1.8-fold compared to baseline.
In patients treated for prevention of recurrent of DVT and PE with 150 mg dabigatran etexilate twice daily no pharmacokinetic data are available.
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, dose-confirmatory trials, patients undergoing elective major orthopaedic surgery (one for knee replacement surgery and one for hip replacement surgery) received Pradaxa (Dabigatran Etexilate Mesylate) 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 (Dabigatran Etexilate Mesylate) 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 17). Better results were seen with the 220 mg dose where the point estimate of Major VTE was slightly better than enoxaparin (table 17).
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 17.
Data for the total VTE and all cause mortality endpoint are shown in table 18.
Data for adjudicated major bleeding endpoints are shown in table 19 below.
Table 17: Analysis of major VTE and VTE-related mortality during the treatment period in the RE-MODEL and the RE-NOVATE orthopaedic surgery studies.
| Trial | Pradaxa (Dabigatran Etexilate Mesylate) 220 mg once daily | Pradaxa (Dabigatran Etexilate Mesylate) 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 18: Analysis of total VTE and all cause mortality during the treatment period in the RE-NOVATE and the RE-MODEL orthopaedic surgery studies.
| Trial | Pradaxa (Dabigatran Etexilate Mesylate) 220 mg once daily | Pradaxa (Dabigatran Etexilate Mesylate) 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 19: Major bleeding events by treatment in the individual RE-MODEL and the RE-NOVATE studies.
| Trial | Pradaxa (Dabigatran Etexilate Mesylate) 220 mg once daily | Pradaxa (Dabigatran Etexilate Mesylate) 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 systemic embolism in adult patients with NVAF 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 Long-term 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 systemic embolism. 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 systemic embolism. Statistical superiority was also analysed.
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 systemic embolism 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 20-22 display details of key results in the overall population:
Table 20: Analysis of first occurrence of stroke or systemic embolism (primary endpoint) during the study period in RE-LY.
| Pradaxa (Dabigatran Etexilate Mesylate) 110 mg twice daily | Pradaxa (Dabigatran Etexilate Mesylate) 150 mg twice daily | Warfarin | |
| Subjects randomized | 6,015 | 6,076 | 6,022 |
| Stroke and/or systemic embolism |
|
|
|
| Incidences (%) | 183 (1.54) | 135 (1.12) | 203 (1.72) |
| Hazard ratio over warfarin (95 % CI) | 0.89 (0.73, 1.09) | 0.65 (0.52, 0.81) |
|
| p value superiority | p=0.2721 | p=0.0001 |
|
% refers to yearly event rate
Table 21: Analysis of first occurrence of ischemic or haemorrhagic strokes during the study period in RE-LY.
| Pradaxa (Dabigatran Etexilate Mesylate) 110 mg twice daily | Pradaxa (Dabigatran Etexilate Mesylate) 150 mg twice daily | Warfarin | |
| Subjects randomized | 6,015 | 6,076 | 6,022 |
| Stroke |
|
|
|
| Incidences (%) | 171 (1.44) | 123 (1.02) | 187 (1.59) |
| Hazard ratio vs. warfarin (95 % CI) | 0.91 (0.74, 1.12) | 0.64 (0.51, 0.81) |
|
| p-value | 0.3553 | 0.0001 |
|
| Systemic embolism |
|
|
|
| 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) | 104 (0.86) | 134 (1.14) |
| Hazard ratio vs. warfarin (95 % CI) | 1.13 (0.89, 1.42) | 0.76 (0.59, 0.98) |
|
| p-value | 0.3138 | 0.0351 |
|
| 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 | 0.0001 | < 0.0001 |
|
% refers to yearly event rate
Table 22: Analysis of all cause and cardiovascular survival during the study period in RE-LY.
| Pradaxa (Dabigatran Etexilate Mesylate) 110 mg twice daily | Pradaxa (Dabigatran Etexilate Mesylate) 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 23-25 display results of the primary efficacy and safety endpoint in relevant sub-populations:
For the primary endpoint, stroke and systemic embolism, no subgroups (i.e., age, weight, gender, renal function, ethnicity, etc.) were identified with a different risk ratio compared to warfarin.
Table 23: Hazard Ratio and 95 % CI for stroke/sytemic embolism by subgroups
| Endpoint | Pradaxa (Dabigatran Etexilate Mesylate) 110 mg twice daily vs. Warfarin | Pradaxa (Dabigatran Etexilate Mesylate) 150 mg twice daily vs. warfarin |
| Age (years) | ||
| < 65 | 1.10 (0.64, 1.87) | 0.51 (0.26, 0.98) |
| 65 ≤ and < 75 | 0.86 (0.62, 1.19) | 0.67 (0.47, 0.95) |
| > 75 | 0.88 (0.66, 1.17) | 0.68 (0.50, 0.92) |
| > 80 | 0.68 (0.44, 1.05) | 0.67 (0.44, 1.02) |
| CrCL(mL/min) |
|
|
| 30 ≤ and < 50 | 0.89 (0.61, 1.31) | 0.48 (0.31, 0.76) |
| 50 ≤ and < 80 | 0.91 (0.68, 1.20) | 0.65 (0.47, 0.88) |
| > 80 | 0.81 (0.51, 1.28) | 0.69 (0.43, 1.12) |
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 24: Hazard Ratio and 95 % CI for major bleeds by subgroups
| Endpoint | Pradaxa (Dabigatran Etexilate Mesylate) 110 mg twice daily vs. Warfarin | Pradaxa (Dabigatran Etexilate Mesylate) 150 mg twice daily vs. Warfarin |
| Age (years) | ||
| < 65 | 0.32 (0.18, 0.57) | 0.35 (0.20, 0.61) |
| 65 ≤ and < 75 | 0.71 (0.56, 0.89) | 0.82 (0.66, 1.03) |
| > 75 | 1.01 (0.84, 1.23) | 1.19 (0.99, 1.43) |
| > 80 | 1.14 (0.86, 1.51) | 1.35 (1.03, 1.76) |
| CrCL(mL/min) |
|
|
| 30 ≤ and < 50 | 1.02 (0.79, 1.32) | 0.94 (0.73, 1.22) |
| 50 ≤ and < 80 | 0.75 (0.61, 0.92) | 0.90 (0.74, 1.09) |
| > 80 | 0.59 (0.43, 0.82) | 0.87 (0.65, 1.17) |
| ASA use | 0.84 (0.69, 1.03) | 0.97 (0.79, 1.18) |
| Clopidogrel use | 0.89 (0.55, 1.45) | 0.92 (0.57, 1.48) |
RELY-ABLE (Long term multi-center extension of dabigatran treatment in patients with atrial fibrillation who completed the RE-LY trial)
The RE-LY extension study (RELY-ABLE) provided additional safety information for a cohort of patients which continued the same dose of dabigatran etexilate as assigned in the RE-LY trial. Patients were eligible for the RELY-ABLE trial if they had not permanently discontinued study medication at the time of their final RE-LY study visit. Enrolled patients continued to receive the same double-blind dabigatran etexilate dose randomly allocated in RE-LY, for up to 43 months of follow up after RE-LY (total mean follow-up RE-LY + RELY-ABLE, 4.5 years). There were 5897 patients enrolled, representing 49 % of patients originally randomly assigned to receive dabigatran etexilate in RE-LY and 86 % of RELY-ABLE-eligible patients.
During the additional 2.5 years of treatment in RELY-ABLE, with a maximum exposure of over 6 years (total exposure in RELY + RELY-ABLE), the long-term safety profile of dabigatran etexilate was confirmed for both test doses 110 mg b.i.d. and 150 mg b.i.d.. No new safety findings were observed.
The rates of outcome events including, major bleed and other bleeding events were consistent with those seen in RE-LY.
Patients who underwent Percutaneous coronary intervention (PCI) with stenting
A prospective, randomized, open-label, blinded endpoint (PROBE) study (Phase IIIb) to evaluate dual-therapy with dabigatran etexilate (110 mg or 150 mg bid) plus clopidogrel or ticagrelor (P2Y12 antagonist) vs. triple-therapy
After oral administration, dabigatran etexilate is rapidly and completely converted to dabigatran, which is the active form in plasma. The cleavage of the prodrug dabigatran etexilate by esterase-catalysed hydrolysis to the active principle dabigatran is the predominant metabolic reaction. The absolute bioavailability of dabigatran following oral administration of Pradaxa (Dabigatran Etexilate Mesylate) was approximately 6.5 %.
After oral administration of Pradaxa (Dabigatran Etexilate Mesylate) in healthy volunteers, the pharmacokinetic profile of dabigatran in plasma is characterized by a rapid increase in plasma concentrations with Cmax attained within 0.5 and 2.0 hours post administration.
Absorption
A study evaluating post-operative absorption of dabigatran etexilate, 1-3 hours following surgery, demonstrated relatively slow absorption compared with that in healthy volunteers, showing a smooth plasma concentration-time profile without high peak plasma concentrations. Peak plasma concentrations are reached at 6 hours following administration in a postoperative period due to contributing factors such as anaesthesia, gastrointestinal paresis, and surgical effects independent of the oral medicinal product formulation. It was demonstrated in a further study that slow and delayed absorption is usually only present on the day of surgery. On subsequent days absorption of dabigatran is rapid with peak plasma concentrations attained 2 hours after medicinal product administration.
Food does not affect the bioavailability of dabigatran etexilate but delays the time to peak plasma concentrations by 2 hours.
Cmax and AUC were dose proportional.
The oral bioavailability may be increased by 75 % after a single dose and 37 % at steady state compared to the reference capsule formulation when the pellets are taken without the Hydroxypropylmethylcellulose (HPMC) capsule shell. Hence, the integrity of the HPMC capsules should always be preserved in clinical use to avoid unintentionally increased bioavailability of dabigatran etexilate.
Distribution
Low (34-35 %) concentration independent binding of dabigatran to human plasma proteins was observed. The volume of distribution of dabigatran of 60-70 L exceeded the volume of total body water indicating moderate tissue distribution of dabigatran.
Biotransformation
Metabolism and excretion of dabigatran were studied following a single intravenous dose of radiolabeled dabigatran in healthy male subjects. After an intravenous dose, the dabigatran-derived radioactivity was eliminated primarily in the urine (85 %). Faecal excretion accounted for 6 % of the administered dose. Recovery of the total radioactivity ranged from 88-94 % of the administered dose by 168 hours post dose.
Dabigatran is subject to conjugation forming pharmacologically active acylglucuronides. Four positional isomers, 1-O, 2-O, 3-O, 4-O-acylglucuronide exist, each accounts for less than 10 % of total dabigatran in plasma. Traces of other metabolites were only detectable with highly sensitive analytical methods. Dabigatran is eliminated primarily in the unchanged form in the urine, at a rate of approximately 100 mL/min corresponding to the glomerular filtration rate.
Elimination
Plasma concentrations of dabigatran showed a biexponential decline with a mean terminal half-life of 11 hours in healthy elderly subjects. After multiple doses a terminal half-life of about 12-14 hours was observed. The half-life was independent of dose. Half-life is prolonged if renal function is impaired as shown in table 28.
Special populations
Renal insufficiency
In phase I studies the exposure (AUC) of dabigatran after the oral administration of Pradaxa (Dabigatran Etexilate Mesylate) is approximately 2.7-fold higher in volunteers with moderate renal insufficiency (CrCL between 30-50 mL/min) than in those without renal insufficiency.
In a small number of volunteers with severe renal insufficiency (CrCL 10-30 mL/min), the exposure (AUC) to dabigatran was approximately 6 times higher and the half-life approximately 2 times longer than that observed in a population without renal insufficiency.
Table 28: Half-life of total dabigatran in healthy subjects and subjects with impaired renal function.
| glomerular filtration rate (CrCL,)
[mL/min] | gMean (gCV %; range) half-life [h] |
| > 80 | 13.4 (25.7 %; 11.0-21.6) |
| > 50-< 80 | 15.3 (42.7 %;11.7-34.1) |
| > 30-< 50 | 18.4 (18.5 %;13.3-23.0) |
| < 30 | 27.2(15.3 %; 21.6-35.0) |
Additionally, dabigatran exposure (at trough and peak) was assessed in a prospective open label randomized pharmacokinetic study in NVAF patients with severe renal impairment (defined as creatinine clearance [CrCl] 15-30 mL/min) receiving dabigatran etexilate 75 mg twice daily.
This regimen resulted in a geometric mean trough concentration of 155 ng/ml (gCV of 76.9 %), measured immediately before administration of the next dose and in a geometric mean peak concentration of 202 ng/ml (gCV of 70.6 %) measured two hours after the administration of the last dose.
Clearance of dabigatran by haemodialysis was investigated in 7 patients with end-stage renal disease (ESRD) without atrial fibrillation. Dialysis was conducted with 700 mL/min dialysate flow rate, four hour duration and a blood flow rate of either 200 mL/min or 350-390 mL/min. This resulted in a removal of 50 % to 60 % of dabigatran concentrations, respectively. The amount of substance cleared by dialysis is proportional to the blood flow rate up to a blood flow rate of 300 mL/min. The anticoagulant activity of dabigatran decreased with decreasing plasma concentrations and the PK/PD relationship was not affected by the procedure.
The median CrCL in RE-LY was 68.4 mL/min. Almost half (45.8 %) of the RE-LY patients had a CrCL > 50-< 80 mL/min. Patients with moderate renal impairment (CrCL between 30-50 mL/min) had on average 2.29-fold and 1.81-fold higher pre- and post-dose dabigatran plasma concentrations, respectively, when compared with patients without renal impairment (CrCL > 80 mL/min).
The median CrCL in the RE-COVER study was 100.4 mL/min. 21.7 % of patients had mild renal impairment (CrCL > 50 - < 80 mL/min) and 4.5% of patients had a moderate renal impairment (CrCL between 30 and 50 mL/min). Patients with mild and moderate renal impairment had at steady state an average 1.8-fold and 3.6-fold higher pre-dose dabigatran plasma concentrations compared with patients with CrCL > 80 mL/min, respectively. Similar values for CrCL were found in RE-COVER II.
The median CrCL in the RE-MEDY and RE-SONATE studies were 99.0 mL/min and 99.7 mL/min, respectively. 22.9 % and 22.5 % of the patients had a CrCL > 50-< 80 mL/min, and 4.1 % and 4.8 % had a CrCL between 30 and 50 mL/min in the RE-MEDY and RE-SONATE studies.
Elderly patients
Specific pharmacokinetic phase I studies with elderly subjects showed an increase of 40 to 60 % in the AUC and of more than 25 % in Cmax compared to young subjects.
The effect by age on exposure to dabigatran was confirmed in the RE-LY study with an about 31 % higher trough concentration for subjects > 75 years and by about 22 % lower trough level for subjects < 65 years compared to subjects between 65 and 75 years.
Hepatic impairment
No change in dabigatran exposure was seen in 12 subjects with moderate hepatic insufficiency (Child Pugh B) compared to 12 controls.
Body weight
The dabigatran trough concentrations were about 20 % lower in patients with a body weight > 100 kg compared with 50-100 kg. The majority (80.8 %) of the subjects were in the > 50 kg and < 100 kg category with no clear difference detected. Limited clinical data in patients < 50 kg are available.
Gender
Active substance exposure in the primary VTE prevention studies was about 40 % to 50 % higher in female patients and no dose adjustment is recommended. In atrial fibrillation patients females had on average 30 % higher trough and post-dose concentrations. No dose adjustment is required.
Ethnic origin
No clinically relevant inter-ethnic differences among Caucasian, African-American, Hispanic, Japanese or Chinese patients were observed regarding dabigatran pharmacokinetics and pharmacodynamics.
Pharmacokinetic interactions
In vitro interaction studies did not show any inhibition or induction of the principal isoenzymes of cytochrome P450. This has been confirmed by in vivo studies with healthy volunteers, who did not show any interaction between this treatment and the following active substances: atorvastatin (CYP3A4), digoxin (P-gp transporter interaction) and diclofenac (CYP2C9).
Haemorrhagic risk
Pradaxa (Dabigatran Etexilate Mesylate) should be used with caution in conditions with an increased risk of bleeding or with concomitant use of medicinal products affecting haemostasis by inhibition of platelet aggregation. Bleeding can occur at any site during therapy with Pradaxa (Dabigatran Etexilate Mesylate). An unexplained fall in haemoglobin and/or haematocrit or blood pressure should lead to a search for a bleeding site.
For situations of life-threatening or uncontrolled bleeding, when rapid reversal of the anticoagulation effect of dabigatran is required, the specific reversal agent (Praxbind, idarucizumab) is available.
In clinical trials, Pradaxa (Dabigatran Etexilate Mesylate) was associated with higher rates of major gastrointestinal (GI) bleeding. An increased risk was seen in the elderly (> 75 years) for the 150 mg twice daily dose regimen. Further risk factors (see also table 4) comprise co-medication with platelet aggregation inhibitors such as clopidogrel and acetylsalicylic acid (ASA) or non steroidal antiinflammatory drugs (NSAID), as well as the presence of esophagitis, gastritis or gastroesophageal reflux.
Risk factors
Table 4 summarises factors which may increase the haemorrhagic risk.
Table 4: Risk factors which may increase the haemorrhagic risk.
| Pharmacodynamic and kinetic factors | Age > 75 years |
| Factors increasing dabigatran plasma levels | Major: - Moderate renal impairment (30-50 mL/min CrCL) - Strong P-gp inhibitors - Mild to moderate P-gp inhibitor co-medication Minor: - Low body weight (< 50 kg) |
| Pharmacodynamic interactions | - ASA and other platelet aggregation inhibitors such as clopidogrel - NSAID - SSRIs or SNRIs - Other medicinal products which may impair haemostasis |
| Diseases / procedures with special haemorrhagic risks | - Congenital or acquired coagulation disorders - Thrombocytopenia or functional platelet defects - Recent biopsy, major trauma - Bacterial endocarditis - Esophagitis, gastritis and gastroesophageal reflux |
Limited data is available in patients < 50 kg.
Precautions and management of the haemorrhagic risk
Benefit-risk assessment
The presence of lesions, conditions, procedures and/or pharmacological treatment , which significantly increase the risk of major bleeding requires a careful benefit-risk assessment. Pradaxa (Dabigatran Etexilate Mesylate) should only be given if the benefit outweighs bleeding risks.
Close clinical surveillance
Close observation for signs of bleeding or anaemia is recommended throughout the treatment period, especially if risk factors are combined (see table 4 above). Particular caution should be exercised when Pradaxa (Dabigatran Etexilate Mesylate) is co-administered with verapamil, amiodarone, quinidine or clarithromycin (P-gp inhibitors) and particularly in the occurrence of bleeding, notably in patients having a mild to moderate renal impairment.
Close observation for signs of bleeding is recommended in patients concomitantly treated with NSAIDs.
Discontinuation of Pradaxa (Dabigatran Etexilate Mesylate)
Dose reduction
Use of proton-pump inhibitors
The administration of a proton-pump inhibitor (PPI) can be considered to prevent GI bleeding.
Laboratory coagulation parameters
Although Pradaxa (Dabigatran Etexilate Mesylate) does not in general require routine anticoagulant monitoring, the measurement of dabigatran related anticoagulation may be helpful to detect excessive high exposure to dabigatran in the presence of additional risk factors.
Diluted thrombin time (dTT), ecarin clotting time (ECT) and activated partial thromboplastin time (aPTT) may provide useful information, but results should be interpreted with caution due to inter-test variability. The International Normalised Ratio (INR) test is unreliable in patients on Pradaxa (Dabigatran Etexilate Mesylate) and false positive INR elevations have been reported. Therefore, INR tests should not be performed.
Table 5 shows coagulation test thresholds at trough that may be associated with an increased risk of bleeding
Table 5: Coagulation test thresholds at trough that may be associated with an increased risk of bleeding.
| Test (trough value) | Indication | |
| Primary prevention of venous thromboembolism in orthopaedic surgery | SPAF and DVT/PE | |
| dTT [ng/mL] | > 67 | > 200 |
| ECT [x-fold upper limit of normal] | No data | > 3 |
| aPTT [x-fold upper limit of normal] | > 1.3 | > 2 |
| INR | Should not be performed | Should not be performed |
Use of fibrinolytic medicinal products for the treatment of acute ischemic stroke
The use of fibrinolytic medicinal products for the treatment of acute ischemic stroke may be considered if the patient presents with a dTT, ECT or aPTT not exceeding the upper limit of normal (ULN) according to the local reference range.
Surgery and interventions
Patients on Pradaxa (Dabigatran Etexilate Mesylate) who undergo surgery or invasive procedures are at increased risk for bleeding. Therefore, surgical interventions may require the temporary discontinuation of Pradaxa (Dabigatran Etexilate Mesylate).
Patients can stay on Pradaxa (Dabigatran Etexilate Mesylate) while being cardioverted. There are no data available for 110 mg twice daily Pradaxa (Dabigatran Etexilate Mesylate) treatment in patients undergoing catheter ablation for atrial fibrillation.
Caution should be exercised when treatment is temporarily discontinued for interventions and anticoagulant monitoring is warranted. Clearance of dabigatran in patients with renal insufficiency may take longer. This should be considered in advance of any procedures. In such cases a coagulation test may help to determine whether haemostasis is still impaired.
Emergency surgery or urgent procedures
Pradaxa (Dabigatran Etexilate Mesylate) should be temporarily discontinued. When rapid reversal of the anticoagulation effect is required the specific reversal agent (Praxbind, idarucizumab) to Pradaxa (Dabigatran Etexilate Mesylate) is available.
Reversing dabigatran therapy exposes patients to the thrombotic risk of their underlying disease. Pradaxa (Dabigatran Etexilate Mesylate) treatment can be re-initiated 24 hours after administration of Praxbind (idarucizumab), if the patient is clinically stable and adequate haemostasis has been achieved.
Subacute surgery/interventions
Pradaxa (Dabigatran Etexilate Mesylate) should be temporarily discontinued. A surgery / intervention should be delayed if possible until at least 12 hours after the last dose. If surgery cannot be delayed the risk of bleeding may be increased. This risk of bleeding should be weighed against the urgency of intervention.
Elective surgery
If possible, Pradaxa (Dabigatran Etexilate Mesylate) should be discontinued at least 24 hours before invasive or surgical procedures. In patients at higher risk of bleeding or in major surgery where complete haemostasis may be required consider stopping Pradaxa (Dabigatran Etexilate Mesylate) 2-4 days before surgery.
Table 6 summarises discontinuation rules before invasive or surgical procedures.
Table 6: Discontinuation rules before invasive or surgical procedures
| Renal function (CrCL in mL/min) | Estimated half-life (hours) | Pradaxa (Dabigatran Etexilate Mesylate) should be stopped before elective surgery | |
| High risk of bleeding or major surgery | Standard risk | ||
| > 80 | ~ 13 | 2 days before | 24 hours before |
| > 50-< 80 | ~ 15 | 2-3 days before | 1-2 days before |
| > 30-< 50 | ~ 18 | 4 days before | 2-3 days before (> 48 hours) |
Spinal anaesthesia/epidural anaesthesia/lumbar puncture
Procedures such as spinal anaesthesia may require complete haemostatic function.
The risk of spinal or epidural haematoma may be increased in cases of traumatic or repeated puncture and by the prolonged use of epidural catheters. After removal of a catheter, an interval of at least 2 hours should elapse before the administration of the first dose of Pradaxa (Dabigatran Etexilate Mesylate). These patients require frequent observation for neurological signs and symptoms of spinal or epidural haematoma.
Postoperative phase
Pradaxa (Dabigatran Etexilate Mesylate) treatment should be resumed / started after the invasive procedure or surgical intervention as soon as possible provided the clinical situation allows and adequate haemostasis has been established.
Patients at risk for bleeding or patients at risk of overexposure, notably patients with moderate renal impairment (CrCL 30-50 mL/min), should be treated with caution.
Patients at high surgical mortality risk and with intrinsic risk factors for thromboembolic events
There are limited efficacy and safety data for Pradaxa (Dabigatran Etexilate Mesylate) available in these patients and therefore they should be treated with caution.
Hip fracture surgery
There is no data on the use of Pradaxa (Dabigatran Etexilate Mesylate) in patients undergoing hip fracture surgery. Therefore treatment is not recommended.
Hepatic impairment
Patients with elevated liver enzymes > 2 ULN were excluded in the main trials. No treatment experience is available for this subpopulation of patients, and therefore the use of Pradaxa (Dabigatran Etexilate Mesylate) is not recommended in this population. Hepatic impairment or liver disease expected to have any impact on survival is contraindicated.
Interaction with P-gp inducers
Concomitant administration of P-gp inducers is expected to result in decreased dabigatran plasma concentrations, and should be avoided.
Myocardial Infarction (MI)
In the phase III study RE-LY the overall rate of MI was 0.82, 0.81, and 0.64 % / year for dabigatran etexilate 110 mg twice daily, dabigatran etexilate 150 mg twice daily and warfarin, respectively, an increase in relative risk for dabigatran of 29 % and 27 % compared to warfarin. Irrespective of therapy, the highest absolute risk of MI was seen in the following subgroups, with similar relative risk: patients with previous MI, patients > 65 years with either diabetes or coronary artery disease, patients with left ventricular ejection fraction < 40 %, and patients with moderate renal dysfunction. Furthermore a higher risk of MI was seen in patients concomitantly taking ASA plus clopidogrel or clopidogrel alone.
In the three active controlled DVT/PE phase III studies, a higher rate of MI was reported in patients who received dabigatran etexilate than in those who received warfarin: 0.4% vs. 0.2% in the short-term RE-COVER and RE-COVER II studies; and 0.8% vs. 0.1% in the long-term RE-MEDY trial. The increase was statistically significant in this study (p=0.022).
In the RE-SONATE study, which compared dabigatran etexilate to placebo, the rate of MI was 0.1% for patients who received dabigatran etexilate and 0.2% for patients who received placebo
Active Cancer Patients (DVT/PE)
The efficacy and safety have not been established for DVT/PE patients with active cancer.
Pradaxa (Dabigatran Etexilate Mesylate) has no or negligible influence on the ability to drive and use machines.
Posology
Primary prevention of Venous Thromboembolism in Orthopaedic Surgery
The recommended doses of Pradaxa (Dabigatran Etexilate Mesylate) and the duration of therapy for primary prevention of venous thromboembolism in orthopaedic surgery are shown in table 1.
Table 1: Dose recommendations and duration of therapy for primary prevention of venous thromboembolism in orthopaedic surgery
| Treatment initiation on the day of surgery 1-4 hours after completed surgery | Maintenance dose starting on the first day after surgery | Duration of maintenance dose | |
| Patients following elective knee replacement surgery | single capsule of 110 mg Pradaxa (Dabigatran Etexilate Mesylate) | 220 mg Pradaxa (Dabigatran Etexilate Mesylate) once daily taken as 2 capsules of 110 mg | 10 days |
| Patients following elective hip replacement surgery | 28-35 days | ||
| Dose reduction recommended | |||
| Patients with moderate renal impairment (creatinine clearance (CrCL) 30-50 mL/min) | single capsule of 75 mg Pradaxa (Dabigatran Etexilate Mesylate) | 150 mg Pradaxa (Dabigatran Etexilate Mesylate) once daily taken as 2 capsules of 75 mg | 10 days (knee replacement surgery) or 28-35 days (hip replacement surgery) |
| Patients who receive concomitant verapamil*, amiodarone, quinidine | |||
| Patients aged 75 or above |
*For patients with moderate renal impairment concomitantly treated with verapamil see Special populations
For both surgeries, if haemostasis is not secured, initiation of treatment should be delayed. If treatment is not started on the day of surgery then treatment should be initiated with 2 capsules once daily.
Assessment of renal function prior to and during Pradaxa (Dabigatran Etexilate Mesylate) treatment
In all patients and especially in the elderly (>75 years), as renal impairment may be frequent in this age group:
- Renal function should be assessed by calculating the creatinine clearance (CrCL) prior to initiation of treatment with Pradaxa (Dabigatran Etexilate Mesylate) to exclude patients with severe renal impairment (i.e. CrCL < 30 mL/min).
- Renal function should also be assessed when a decline in renal function is suspected during treatment (e.g. hypovolaemia, dehydration, and in case of concomitant use of certain medicinal products).
The method to be used to estimate renal function (CrCL in mL/min) is the Cockcroft-Gault method.
Missed dose
It is recommended to continue with the remaining daily doses of Pradaxa (Dabigatran Etexilate Mesylate) at the same time of the next day.
No double dose should be taken to make up for missed individual doses.
Discontinuation of Pradaxa (Dabigatran Etexilate Mesylate)
Pradaxa (Dabigatran Etexilate Mesylate) treatment should not be discontinued without medical advice. Patients should be instructed to contact the treating physician if they develop gastrointestinal symptoms such as dyspepsia.
Switching
Pradaxa (Dabigatran Etexilate Mesylate) treatment to parenteral anticoagulant:
It is recommended to wait 24 hours after the last dose before switching from Pradaxa (Dabigatran Etexilate Mesylate) to a parenteral anticoagulant.
Parenteral anticoagulants to Pradaxa (Dabigatran Etexilate Mesylate):
The parenteral anticoagulant should be discontinued and Pradaxa (Dabigatran Etexilate Mesylate) should be started 0-2 hours prior to the time that the next dose of the alternate therapy would be due, or at the time of discontinuation in case of continuous treatment (e.g. intravenous Unfractionated Heparin (UFH)).
Special populations
Renal impairment
Treatment with Pradaxa (Dabigatran Etexilate Mesylate) in patients with severe renal impairment (CrCL < 30 mL/min) is contraindicated.
1).Concomitant use of Pradaxa (Dabigatran Etexilate Mesylate) with mild to moderate P-glycoprotein (P-gp) inhibitors, i.e. amiodarone, quinidine or verapamil
5). In this situation Pradaxa (Dabigatran Etexilate Mesylate) and these medicinal products should be taken at the same time.In patients with moderate renal impairment and concomitantly treated with verapamil, a dose reduction of Pradaxa (Dabigatran Etexilate Mesylate) to 75 mg daily should be considered.
Elderly
1).Weight
There is very limited clinical experience in patients with a body weight < 50 kg or > 110 kg at the recommended posology. Given the available clinical and kinetic data no adjustment is necessary , but close clinical surveillance is recommended.
Gender
No dose adjustment is necessary.
Paediatric population
There is no relevant use of Pradaxa (Dabigatran Etexilate Mesylate) in the paediatric population for the indication of primary prevention of venous thromboembolic events in patients who have undergone elective total hip replacement surgery or total knee replacement surgery.
Prevention of stroke and systemic embolism in adult patients with NVAF with one or more risk factors (SPAF)
Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), and prevention of recurrent DVT, and PE in adults (DVT/PE)
The recommended doses of Pradaxa (Dabigatran Etexilate Mesylate) in the indications SPAF, DVT and PE are shown in table 2.
Table 2: Dose recommendations for SPAF, DVT and PE
| Dose recommendation | |
| Prevention of stroke and systemic embolism in adult patients with NVAF with one or more risk factors (SPAF) | 300 mg Pradaxa (Dabigatran Etexilate Mesylate) taken as one 150 mg capsule twice daily |
| Treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), and prevention of recurrent DVT, and PE in adults (DVT/PE) | 300 mg Pradaxa (Dabigatran Etexilate Mesylate) taken as one 150 mg capsule twice daily following treatment with a parenteral anticoagulant for at least 5 days |
| Dose reduction recommended | |
| Patients aged >80 years | daily dose of 220 mg Pradaxa (Dabigatran Etexilate Mesylate) taken as one 110 mg capsule twice daily |
| Patients who receive concomitant verapamil | |
| Dose reduction for consideration | |
| Patients between 75-80 years | daily dose of Pradaxa (Dabigatran Etexilate Mesylate) of 300 mg or 220 mg should be selected based on an individual assessment of the thromboembolic risk and the risk of bleeding |
| Patients with moderate renal impairment (CrCL 30-50 mL/min) | |
| Patients with gastritis, esophagitis or gastroesophageal reflux | |
| Other patients at increased risk of bleeding |
For DVT/PE the recommendation for the use of Pradaxa (Dabigatran Etexilate Mesylate) 220 mg taken as one 110 mg capsule twice daily is based on pharmacokinetic and pharmacodynamic analyses and has not been studied in this clinical setting.5, 5.1 and 5.2.
In case of intolerability to Pradaxa (Dabigatran Etexilate Mesylate), patients should be instructed to immediately consult their treating physician in order to be switched to alternate acceptable treatment options for prevention of stroke and systemic embolism associated with atrial fibrillation or for DVT/PE.
Assessment of renal function prior to and during Pradaxa (Dabigatran Etexilate Mesylate) treatment
In all patients and especially in the elderly (>75 years), as renal impairment may be frequent in this age group:
- Renal function should be assessed by calculating the creatinine clearance (CrCL) prior to initiation of treatment with Pradaxa (Dabigatran Etexilate Mesylate) to exclude patients with severe renal impairment (i.e. CrCL < 30 mL/min).
- Renal function should also be assessed when a decline in renal function is suspected during treatment (e.g. hypovolaemia, dehydration, and in case of concomitant use of certain medicinal products).
Additional requirements in patients with mild to moderate renal impairment and in patients aged over 75 years:
- Renal function should be assessed during treatment with Pradaxa (Dabigatran Etexilate Mesylate) at least once a year or more frequently as needed in certain clinical situations when it is suspected that the renal function could decline or deteriorate (e.g. hypovolaemia, dehydration, and in case of concomitant use of certain medicinal products).
The method to be used to estimate renal function (CrCL in mL/min) is the Cockcroft-Gault method.
Duration of use
The duration of use of Pradaxa (Dabigatran Etexilate Mesylate) in the indications SPAF, DVT and PE are shown in table 3.
Table 3: Duration of use for SPAF and DVT/PE
| Indication | Duration of use |
| SPAF | Therapy should be continued long term. |
| DVT/PE | The duration of therapy should be individualised after careful assessment of the treatment benefit against the risk for bleeding. Short duration of therapy (at least 3 months) should be based on transient risk factors (e.g. recent surgery, trauma, immobilisation) and longer durations should be based on permanent risk factors or idiopathic DVT or PE. |
Missed dose
A forgotten Pradaxa (Dabigatran Etexilate Mesylate) dose may still be taken up to 6 hours prior to the next scheduled dose. From 6 hours prior to the next scheduled dose on, the missed dose should be omitted.
No double dose should be taken to make up for missed individual doses.
Discontinuation of Pradaxa (Dabigatran Etexilate Mesylate)
Pradaxa (Dabigatran Etexilate Mesylate) treatment should not be discontinued without medical advice. Patients should be instructed to contact the treating physician if they develop gastrointestinal symptoms such as dyspepsia.
Switching
Pradaxa (Dabigatran Etexilate Mesylate) treatment to parenteral anticoagulant:
It is recommended to wait 12 hours after the last dose before switching from Pradaxa (Dabigatran Etexilate Mesylate) to a parenteral anticoagulant.
Parenteral anticoagulants to Pradaxa (Dabigatran Etexilate Mesylate):
The parenteral anticoagulant should be discontinued and Pradaxa (Dabigatran Etexilate Mesylate) should be started 0-2 hours prior to the time that the next dose of the alternate therapy would be due, or at the time of discontinuation in case of continuous treatment (e.g. intravenous Unfractionated Heparin (UFH)).
Pradaxa (Dabigatran Etexilate Mesylate) treatment to Vitamin K antagonists (VKA):
The starting time of the VKA should be adjusted based on CrCL as follows:
- CrCL > 50 mL/min, VKA should be started 3 days before discontinuing Pradaxa (Dabigatran Etexilate Mesylate)
- CrCL > 30-< 50 mL/min, VKA should be started 2 days before discontinuing Pradaxa (Dabigatran Etexilate Mesylate)
Because Pradaxa (Dabigatran Etexilate Mesylate) can impact the International Normalized Ratio (INR), the INR will better reflect VKA's effect only after Pradaxa (Dabigatran Etexilate Mesylate) has been stopped for at least 2 days. Until then, INR values should be interpreted with caution.
VKA to Pradaxa (Dabigatran Etexilate Mesylate):
The VKA should be stopped. Pradaxa (Dabigatran Etexilate Mesylate) can be given as soon as the INR is < 2.0.
Cardioversion (SPAF)
Patients can stay on Pradaxa (Dabigatran Etexilate Mesylate) while being cardioverted.
Catheter ablation for atrial fibrillation (SPAF)
There are no data available for 110 mg twice daily Pradaxa (Dabigatran Etexilate Mesylate) treatment.
Percutaneous coronary intervention (PCI) with stenting (SPAF)
Patients with non valvular atrial fibrillation who undergo a PCI with stenting can be treated with Pradaxa (Dabigatran Etexilate Mesylate) in combination with antiplatelets after haemostasis is achieved.
Special populations
Elderly
For dose modifications in this population see table 2 above.
Patients at risk of bleeding
Patients with an increased bleeding risk should be closely monitored clinically (looking for signs of bleeding or anaemia). Dose adjustment should be decided at the discretion of the physician, following assessment of the potential benefit and risk to an individual patient (see table 2 above). A coagulation test may help to identify patients with an increased bleeding risk caused by excessive dabigatran exposure. When excessive dabigatran exposure is identified in patients at high risk of bleeding, a reduced dose of 220 mg taken as one 110 mg capsule twice daily is recommended. When clinically relevant bleeding occurs, treatment should be interrupted.
Renal impairment
Treatment with Pradaxa (Dabigatran Etexilate Mesylate) in patients with severe renal impairment (CrCL < 30 mL/min) is contraindicated.
No dose adjustment is necessary in patients with mild renal impairment (CrCL 50- ≤ 80 mL/min). For patients with moderate renal impairment (CrCL 30-50 mL/min) the recommended dose of Pradaxa (Dabigatran Etexilate Mesylate) is also 300 mg taken as one 150 mg capsule twice daily. However, for patients with high risk of bleeding, a dose reduction of Pradaxa (Dabigatran Etexilate Mesylate) to 220 mg taken as one 110 mg capsule twice daily should be considered. Close clinical surveillance is recommended in patients with renal impairment.
Concomitant use of Pradaxa (Dabigatran Etexilate Mesylate) with mild to moderate P-glycoprotein (P-gp) inhibitors, i.e. amiodarone, quinidine or verapamil
No dose adjustment is necessary for concomitant use of amiodarone or quinidine.
5). In this situation Pradaxa (Dabigatran Etexilate Mesylate) and verapamil should be taken at the same time.Weight
No dose adjustment is necessary , but close clinical surveillance is recommended in patients with a body weight < 50 kg.
Gender
No dose adjustment is necessary.
Paediatric population
There is no relevant use of Pradaxa (Dabigatran Etexilate Mesylate) in the paediatric population for the indication of prevention of stroke and systemic embolism in patients with NVAF.
For the indication DVT/PE, the safety and efficacy of Pradaxa (Dabigatran Etexilate Mesylate) in children from birth to less than 18 years of age have not yet been established.1, but no recommendation on a posology can be made.
Method of administration
Pradaxa (Dabigatran Etexilate Mesylate) is for oral use.
The capsules can be taken with or without food. Pradaxa (Dabigatran Etexilate Mesylate) should be swallowed as a whole with a glass of water, to facilitate delivery to the stomach.
Patients should be instructed not to open the capsule as this may increase the risk of bleeding.
When taking Pradaxa (Dabigatran Etexilate Mesylate) capsules out of the blister pack, the following instructions should be followed:
- One individual blister should be teared off from the blister card along the perforated line.
- The backing foil should be peeled off and the capsule can be removed.
- The hard capsules should not be pushed through the blister foil.
- The blister foil should only be peeled off, when a hard capsule is required.
When taking a hard capsule out of the bottle, the following instructions should be observed:
- The cap opens by pushing and turning.
- After taking the capsule out, the cap should be returned on the bottle right away and the bottle should be tightly closed.
Any unused medicinal product or waste material should be disposed of in accordance with local requirements.
