英文药名：Praxbind（idarucizumab solution for injection/infusion）

中文药名：达比加群酯注射溶液

生产厂家：勃林格殷格翰制药
药品介绍
2015年11月27日，欧盟委员会批准勃林格殷格翰Praxbind（idarucizumab），在急诊外科/紧急手术或出现危及生命或无法控制的出血时，该药物可迅速并特定拮抗达比加群酯的抗凝作用。Idarucizumab 是在欧盟获得批准的首个用于非维生素K拮抗剂口服抗凝剂（NOAC）的特定拮抗剂。
抗凝血剂对处于血栓栓塞事件风险的患者提供了重要的受益。然而，虽然很少发生，但一旦情况发生时能够拮抗抗凝作用在医学上是必要的，柏林Vivantes Neukoelln医学中心肾脏学和重症监护医学、血管医学、心脏病学主任、RE-VERSE AD临床研究在德国的主要研究者Darius教授称。Praxbind的批准现在为我及我的同事提供了一种重要的选择，在需要拮抗抗凝作用的紧急情况下可以用来管理服用达比加群酯的患者。
研究中，Idarucizumab在用药数分钟内的拮抗作用是明显
此次批准基于健康志愿者以及RE-VERSE AD临床研究一项期中分析的数据。在研究中，Idarucizumab的拮抗作用在5克剂量用药后的数分钟内是非常明显的。在几乎所有的患者中，该药物对抗凝血剂的拮抗作用是完全的，并且这种拮抗作用至少能持续 12小时。
我非常高兴我们现在能够向欧洲患者及医师提供Praxbind，它是唯一特定用于新型口服抗凝剂的拮抗剂，勃林格殷格翰医学、心血管治疗领域副总裁Kreuzer 教授评论称。
此次批准之后，勃林格殷格翰再次在抗凝治疗的进展中处于领先，就像当时我们推出达比加群酯时那样。虽然我们期望 Praxbind 尽可能不要在临床实践中使用到，但这种特定拮抗剂的可用性现在可以使医师及患者在选择达比加群酯时增加信心。
Idarucizumab 在被欧盟委员会批准之前，欧盟药品管理局人用医药产品委员会在 2015年9月份对该产品发布了积极的意见。Idarucizumab已于2015年10月被美国FDA批准。

Praxbind 2.5 g/50 mL solution for injection/infusion
1. Name of the medicinal product
Praxbind 2.5 g/50 mL solution for injection/infusion
2. Qualitative and quantitative composition
Each mL of solution for injection/infusion contains 50 mg idarucizumab.
Each vial contains 2.5 g idarucizumab in 50 mL.
Idarucizumab is produced by recombinant DNA technology in Chinese Hamster Ovary cells.
Excipients with known effect:
Each 50 mL vial contains 2 g sorbitol and 25 mg sodium (see section 4.4).
For the full list of excipients, see section 6.1.
3. Pharmaceutical form
Solution for injection/infusion
Clear to slightly opalescent, colourless to slightly yellow solution.
4. Clinical particulars
4.1 Therapeutic indications
Praxbind is a specific reversal agent for dabigatran and is indicated in adult patients treated with Pradaxa (dabigatran etexilate) when rapid reversal of its anticoagulant effects is required:
• For emergency surgery/urgent procedures
• In life-threatening or uncontrolled bleeding.
4.2 Posology and method of administration
Restricted to hospital use only.
Posology
The recommended dose of Praxbind is 5 g (2x2.5 g/50 mL).
In a subset of patients, recurrence of plasma concentrations of unbound dabigatran and concomitant prolongation of clotting tests have occurred up to 24 hours after administration of idarucizumab (see section 5.1).
Administration of a second 5 g dose of Praxbind may be considered in the following situations:
• recurrence of clinically relevant bleeding together with prolonged clotting times, or
• if potential re-bleeding would be life-threatening and prolonged clotting times are observed, or
• patients require a second emergency surgery/urgent procedure and have prolonged clotting times.
Relevant coagulation parameters are activated Partial Thromboplastin Time (aPTT), diluted Thrombin Time (dTT) or Ecarin Clotting Time (ECT) (see section 5.1).
A maximum daily dose has not been investigated.
Restarting Antithrombotic Therapy
Pradaxa (dabigatran etexilate) treatment can be re-initiated 24 hours after administration of Praxbind, if the patient is clinically stable and adequate haemostasis has been achieved.
After administration of Praxbind, other antithrombotic therapy (e.g. low-molecular weight heparin) can be started at any time, if the patient is clinically stable and adequate haemostasis has been achieved.
Absence of antithrombotic therapy exposes patients to the thrombotic risk of their underlying disease or condition.
Patients with renal impairment
No dose adjustment is required in renally impaired patients. Renal impairment did not impact the reversal effect of idarucizumab.
Patients with hepatic impairment
No dose adjustment is required in hepatically impaired patients (see section 5.2).
Elderly
No dose adjustment is required in elderly patients aged 65 years and above (see section 5.2).
Paediatric population
The safety and efficacy of Praxbind in children below the age of 18 years have not yet been established. No data are available.
Method of administration
Intravenous use.
Praxbind (2x2.5 g/50 mL) is administered intravenously as two consecutive infusions over 5 to 10 minutes each or as a bolus injection.
For additional instructions for use and handling see section 6.6.
4.3 Contraindications
None.
4.4 Special warnings and precautions for use
Idarucizumab binds specifically to dabigatran and reverses its anticoagulant effect. It will not reverse the effects of other anticoagulants (see section 5.1).
Praxbind treatment can be used in conjunction with standard supportive measures, which should be considered as medically appropriate.
Hypersensitivity
The risk of using Praxbind in patients with known hypersensitivity (e.g. anaphylactoid reaction) to idarucizumab or to any of the excipients needs to be weighed cautiously against the potential benefit of such an emergency treatment. If an anaphylactic reaction or other serious allergic reaction occurs, administration of Praxbind should be discontinued immediately and appropriate therapy initiated.
Hereditary fructose intolerance
The recommended dose of Praxbind contains 4 g sorbitol as an excipient. In patients with hereditary fructose intolerance, parenteral administration of sorbitol has been associated with reports of hypoglycemia, hypophosphatemia, metabolic acidosis, increase in uric acid, acute liver failure with breakdown of excretory and synthetic function, and death. Therefore, in patients with hereditary fructose intolerance the risk of treatment with Praxbind must be weighed against the potential benefit of such an emergency treatment. If Praxbind is administered in these patients, intensified medical care during Praxbind exposure and within 24 hours of exposure is required.
Thromboembolic Events
Patients being treated with dabigatran have underlying disease states that predispose them to thromboembolic events. Reversing dabigatran therapy exposes patients to the thrombotic risk of their underlying disease. To reduce this risk, resumption of anticoagulant therapy should be considered as soon as medically appropriate (see section 4.2).
Urinary protein testing
Praxbind causes transient proteinuria as a physiologic reaction to renal protein overflow after bolus/short term application of 5g idarucizumab intravenously (see section 5.2). The transient proteinuria is not indicative of renal damage, which should be taken into account for urine testing.
Sodium content
This medicinal product contains 2,2 mmol (or 50 mg) sodium per dose. To be taken into consideration by patients on a controlled sodium diet.
4.5 Interaction with other medicinal products and other forms of interaction
No formal interaction studies with Praxbind and other medicinal products have been performed. Based on the pharmacokinetic properties and the high specificity in binding to dabigatran, clinically relevant interactions with other medicinal products are considered unlikely.
Preclinical investigations with idarucizumab have shown no interactions with
• volume expanders.
• coagulation factor concentrates, such as prothrombin complex concentrates (PCCs, e.g. 3 factor and 4 factor), activated PCCs (aPCCs) and recombinant factor VIIa.
• other anticoagulants (e.g. thrombin inhibitors other than dabigatran, Factor Xa inhibitors including low-molecular weight heparin, vitamin K-antagonists, heparin). Thus idarucizumab will not reverse the effects of other anticoagulants.
4.6 Fertility, pregnancy and lactation
Pregnancy
There are no data for the use of Praxbind in pregnant women. Reproductive and developmental toxicity studies have not been performed, given the nature and the intended clinical use of the medicinal product. Praxbind may be used during pregnancy, if the expected clinical benefit outweighs the potential risks.
Breast-feeding
It is unknown whether idarucizumab is excreted in human milk.
Fertility
There are no data on the effect of Praxbind on fertility (see section 5.3).
4.7 Effects on ability to drive and use machines
Not relevant.
4.8 Undesirable effects
The safety of Praxbind has been evaluated in 224 healthy subjects as well as 123 patients in an ongoing phase III trial, who had uncontrolled bleeding or required emergency surgery or procedures and were under treatment with Pradaxa (dabigatran etexilate).
No adverse reactions have been identified.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via:
United Kingdom
Yellow Card Scheme
Website: www.mhra.gov.uk/yellowcard
Ireland
HPRA Pharmacovigilance
Earlsfort Terrace
IRL - Dublin 2
Tel: +353 1 6764971
Fax: +353 1 6762517
Website: www.hpra.ie
e-mail: medsafety@hpra.ie
Malta
ADR Reporting
Website: www.medicinesauthority.gov.mt/adrportal
4.9 Overdose
There is no clinical experience with overdoses of Praxbind.
The highest single dose of Praxbind studied in healthy subjects was 8 g. No safety signals have been identified in this group.
5. Pharmacological properties
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: not yet assigned, ATC code: not yet assigned
Mechanism of action
Idarucizumab is a specific reversal agent for dabigatran. It is a humanized monoclonal antibody fragment (Fab) that binds to dabigatran with very high affinity, approximately 300-fold more potent than the binding affinity of dabigatran for thrombin. The idarucizumab-dabigatran complex is characterised by a rapid on-rate and extremely slow off-rate resulting in a very stable complex. Idarucizumab potently and specifically binds to dabigatran and its metabolites and neutralises their anticoagulant effect.
Clinical efficacy and safety
Three randomised, double-blind, placebo-controlled Phase I studies in 283 subjects (224 treated with idarucizumab) were conducted to assess the safety, efficacy, tolerability, pharmacokinetics and pharmacodynamics of idarucizumab, given alone or after administration of dabigatran etexilate. The investigated population consisted of healthy subjects and subjects exhibiting specific population characteristics covering age, body weight, race, sex and renal impairment. In these studies the doses of idarucizumab ranged from 20 mg to 8 g and the infusion times ranged from 5 minutes to 1 hour.
Representative values for pharmacokinetic and pharmacodynamics parameters were established on the basis of healthy subjects aged 45-64 years receiving 5 g idarucizumab (see sections 5.1 and 5.2).
A prospective, open-label, non-randomized, uncontrolled study (RE-VERSE AD) is currently ongoing to investigate the treatment of adult patients who presented with dabigatran-related life-threatening or uncontrolled bleeding (Group A) or who required emergency surgery or urgent procedures (Group B). The primary endpoint was the maximum percentage reversal of the anticoagulant effect of dabigatran within 4 hours after the administration of idarucizumab, based on central laboratory determination of dilute thrombin time (dTT) or ecarin clotting time (ECT). A key secondary endpoint is the restoration of haemostasis.
An interim analysis of RE-VERSE AD included data for 123 patients: 66 patients with serious bleeding (Group A) and 57 requiring an urgent procedure (Group B). Approximately half of the patients in each group were male. The median age was 77 years and the median creatinine clearance was 61 mL/min. Approximately 68% of patients in Group A and 63% of patients in Group B had been treated with dabigatran 110 mg twice daily. Results of central laboratory evaluations were available for a subset of 90 patients (51 in Group A, 39 in Group B).
Most patients (>89%), in both Groups A and B, achieved complete reversal of the anticoagulant effect of dabigatran as measured by dTT or ECT in the first 4 hours after administration of 5 g idarucizumab. Reversal effects were evident immediately after administration.

Figure 1 – Reversal of dabigatran-induced clotting time prolongation determined by dTT in 90 patients from the RE-VERSE AD study

Figure 2 – Reversal of dabigatran-induced clotting time prolongation determined by aPTT in 90 patients from the RE-VERSE AD study

Restoration of haemostasis was achieved in 91% of evaluable patients who had serious bleeding and normal haemostasis was observed in 92% of patients who required an urgent procedure.
Of the total 123 patients, 26 patients died; each of these deaths could be attributed either as a complication of the index event or associated with co-morbidities. Thrombotic events were reported in 5 patients, none of which were on antithrombotic therapy at the time of the event, and in each of these cases, the thrombotic event could be attributed to the underlying medical condition of the patient. Mild symptoms of potential hypersensitivity (pyrexia, bronchospasm, hyperventilation, rash or pruritus) were reported. A causal relationship to idarucizumab could not be established. Further adverse events, reported in greater than or equal to 5% of patients, were hypokalemia (9/123; 7%), delirium (9/123; 7%), constipation (8/123; 7%), pyrexia (7/123; 6%), pneumonia (7/123; 6%).
Pharmacodynamic effects
The pharmacodynamics of idarucizumab after administration of dabigatran etexilate were investigated in 141 subjects in Phase I studies, of which data for a representative subgroup of 6 healthy subjects aged 45 to 64 years receiving a dose of 5 g as intravenous infusion are presented. The median peak dabigatran exposure in the investigated healthy subjects was in the range of a twice daily administration of 150 mg dabigatran etexilate in patients.
Effect of idarucizumab on the exposure and anticoagulant activity of dabigatran
Immediately after the administration of idarucizumab, the plasma concentrations of unbound dabigatran were reduced by more than 99 %, resulting in levels with no anticoagulant activity.
The majority of the patients showed sustained reversal of dabigatran plasma concentrations up to 12 hours (>90%). In a subset of patients, recurrence of plasma levels of unbound dabigatran and concomitant elevation of clotting tests was observed, possibly due to re-distribution of dabigatran from the periphery. This occurred 2-24 hours after administration of idarucizumab mainly at timepoints ≥12 hours.
Figure 3 – Plasma-levels of unbound dabigatran in the representative group of healthy subjects (administration of idarucizumab or placebo at 0 h)

Dabigatran prolongs the clotting time of coagulation markers such as diluted Thrombin Time (dTT), Thrombin Time (TT), activated Partial Thromboplastin Time (aPTT) and Ecarin Clotting Time (ECT), which provide an approximate indication of the anticoagulation intensity. A value in the normal range after administration of idarucizumab indicates that a patient is no longer anticoagulated. A value above the normal range may reflect residual active dabigatran or other clinical conditions e.g., presence of other drugs or transfusion coagulopathy. These tests were used to assess the anticoagulant effect of dabigatran. A complete and sustained reversal of dabigatran-induced clotting time prolongation was observed immediately after the idarucizumab infusion, lasting over the entire observation period of at least 24 h.
Figure 4 – Reversal of dabigatran-induced clotting time prolongation determined by dTT in the representative group of healthy subjects (administration of idarucizumab or placebo at 0 h)

Figure 5 – Reversal of dabigatran-induced clotting time prolongation determined by ECT in the representative group of healthy subjects (administration of idarucizumab or placebo at 0 h)

Thrombin generation parameters
Dabigatran exerts pronounced effects on parameters of the endogenous thrombin potential (ETP). Idarucizumab treatment normalised both thrombin lag time ratio and time to peak ratio to baseline levels as determined 0.5 to 12 hours after the end of the idarucizumab infusion. Idarucizumab alone has shown no procoagulant effect measured as ETP. This suggests that idarucizumab has no prothrombotic effect.
Re-administration of dabigatran etexilate
24 hours after the idarucizumab infusion, re-administration of dabigatran etexilate resulted in expected anticoagulant activity.
Immunogenicity
Serum samples from 283 subjects (224 treated with idarucizumab) were tested for antibodies to idarucizumab before and after treatment.
Pre-existing antibodies with cross-reactivity to idarucizumab were detected in approximately 13 % (36/283) of the subjects. No impact on the pharmacokinetics or the reversal effect of idarucizumab or hypersensitivity reactions were observed in these subjects.
Treatment-emergent anti-idarucizumab antibodies with low titers were observed in 4 % (9/224) of the subjects suggesting a low immunogenic potential of idarucizumab. In a subgroup of 6 subjects, idarucizumab was administered a second time, two months after the first administration. No anti-idarucizumab antibodies were detected in these subjects prior to the second administration. In one subject, treatment-emergent anti-idarucizumab antibodies were detected after the second administration.
Preclinical pharmacodynamics
A trauma model in pigs was performed using a blunt liver injury after dosing with dabigatran to achieve supratherapeutic concentrations of about 10-fold of human plasma levels. Idarucizumab effectively and rapidly reversed the life-threatening bleeding within 15 min after the injection. All pigs survived at idarucizumab doses of approximately 2.5 and 5 g. Without idarucizumab, the mortality in the anticoagulated group was 100 %.
The European Medicines Agency has deferred the obligation to submit the results of studies with Praxbind in one or more subsets of the paediatric population in the prevention and treatment of dabigatran associated haemorrhage (see section 4.2 for information on paediatric use).
5.2 Pharmacokinetic properties
The pharmacokinetics of idarucizumab were investigated in 224 subjects in Phase I studies, of which data for a representative subgroup of 6 healthy subjects aged 45 to 64 years receiving a dose of 5 g as intravenous infusion are presented.
Distribution
Idarucizumab exhibited multiphasic disposition kinetics and limited extravascular distribution. Following the intravenous infusion of a 5 g dose, the geometric mean volume of distribution at steady state (Vss) was 8.9 L (geometric coefficient of variation (gCV) 24.8 %).
Biotransformation
Several pathways have been described that may contribute to the metabolism of antibodies. All of these pathways involve biodegradation of the antibody to smaller molecules, i.e. small peptides or amino acids, which are then reabsorbed and incorporated in the general protein synthesis.
Elimination
Idarucizumab was rapidly eliminated with a total clearance of 47.0 mL/min (gCV 18.4 %), an initial half-life of 47 minutes (gCV 11.4 %) and a terminal half-life of 10.3 h (gCV 18.9 %). After intravenous administration of 5 g idarucizumab, 32.1 % (gCV 60.0 %) of the dose was recovered in urine within a collection period of 6 hours and less than 1 % in the following 18 hours. The remaining part of the dose is assumed to be eliminated via protein catabolism, mainly in the kidney.
After treatment with idarucizumab proteinuria has been observed. The transient proteinuria is a physiologic reaction to renal protein overflow after bolus/short term application of 5g idarucizumab intravenously. The transient proteinuria usually peaked about 4 h after idarucizumab administration and normalised within 12-24 hours. In single cases the transient proteinuria persisted for more than 24 hours.
Patients with renal impairment
In Phase I studies Praxbind has been investigated in subjects with a creatinine clearance ranging from 44 to 213 mL/min. Subjects with a creatinine clearance below 44 mL/min have not been studied in Phase I.
Depending on the degree of renal impairment the total clearance was reduced compared to healthy subjects, leading to an increased exposure of idarucizumab.
Based on pharmacokinetic data from 68 patients with different degrees of renal function (median creatinine clearance 19.2 - 126 mL/min) it is estimated that mean idarucizumab exposure (AUC0–24h) increases by 26% in patients with mild (CrCl 60-90 mL/min), by 78% in moderate (30-60 mL/min) and by 199% in severe (0-30 mL/min) renal impairment. Since dabigatran is also excreted primarily via the kidneys, increases in the exposure to dabigatran are also seen with worsening renal function.
Based on these data and the extent of reversal of the anticoagulant effect of dabigatran in patients, renal impairment does not appear to impact the reversal effect of idarucizumab, although the conclusion for patients with severe renal impairment is drawn from only a small subset of patients.
Patients with hepatic impairment
Praxbind has not been studied in patients with hepatic impairment. Antibody fragments are known to be eliminated mainly by proteolytic catabolism in the kidney. An impact of hepatic impairment on the pharmacokinetics of idarucizumab is not expected.
Older people/Sex/Race
Based on population pharmacokinetic analyses, sex, age, and race do not have a clinically meaningful effect on the pharmacokinetics of idarucizumab.
5.3 Preclinical safety data
Preclinical data reveal no special hazard for humans based on repeated dose toxicity studies of up to four weeks in rats and two weeks in monkeys. Safety pharmacology studies have demonstrated no effects on the respiratory, central nervous or cardiovascular system.
Studies to evaluate the mutagenic and carcinogenic potential of idarucizumab have not been performed. Based on its mechanism of action and the characteristics of proteins no carcinogenic or genotoxic effects are anticipated.
Studies to assess the potential reproductive effects of idarucizumab have not been performed. No treatment-related effects have been identified in reproductive tissues of either sex during repeat dose intravenous toxicity studies of up to four weeks in the rat and two weeks in monkeys. Additionally, no idarucizumab binding to human reproductive tissues was observed in a tissue cross-reactivity study. Therefore, preclinical results do not suggest a risk to fertility or embryo-fetal development.
No local irritation of the blood vessel was observed after i.v. or paravenous administration of idarucizumab. The idarucizumab formulation did not produce haemolysis of human whole blood in vitro.
6. Pharmaceutical particulars
6.1 List of excipients
sodium acetate trihydrate
acetic acid
sorbitol
polysorbate 20
water for injection
6.2 Incompatibilities
This medicinal product must not be mixed with other medicinal products.
6.3 Shelf life
24 months.
After opening the vial, chemical and physical in-use stability of idarucizumab has been demonstrated for 1 hour at room temperature.
From a microbiological point of view, unless the method of opening precludes the risk of microbial contamination, the product shall be used immediately after opening. If not used immediately, in-use storage times and conditions prior to use are the responsibility of the user.
6.4 Special precautions for storage
Store in a refrigerator (2 °C-8 °C).
Do not freeze.
Store in the original package in order to protect from light.
Prior to use, the unopened vial may be kept at room temperature (25 °C) for up to 48 hours, if stored in the original package in order to protect from light, or up to 6 hours when exposed to light.
For storage conditions after opening of the medicinal product, see section 6.3.
6.5 Nature and contents of container
50 mL solution in a glass vial (type I glass), with a butyl rubber stopper, an aluminium cap and a label with integrated hanger.
Pack size of 2 vials.
6.6 Special precautions for disposal and other handling
Parenteral medicinal products such as Praxbind should be inspected visually for particulate matter and discoloration prior to administration.
Praxbind must not be mixed with other medicinal products. A pre-existing intravenous line may be used for administration of Praxbind. The line must be flushed with sodium chloride 9 mg/ml (0.9 %) solution for injection prior to and at the end of infusion. No other infusion should be administered in parallel via the same intravenous access.
Praxbind is for single-use only and does not contain preservatives (see section 6.3).
No incompatibilities between Praxbind and polyvinyl chloride, polyethylene or polyurethane infusion sets or polypropylene syringes have been observed.
7. Marketing authorisation holder
Boehringer Ingelheim International GmbH
Binger Str. 173
D-55216 Ingelheim am Rhein
Germany
8. Marketing authorisation number(s)
EU/1/15/1056/001
9. Date of first authorisation/renewal of the authorisation
Date of first authorisation: 20 November 2015
10. Date of revision of the text
Detailed information on this medicinal product is available on the website of the European Medicines Agency http://www.ema.europa.eu.