1. Baseline assessment prior to initiation of dabigatran (Pradaxa )

Transcription

1 Dabigatran for stroke prevention in Atrial Fibrillation Clinical Guideline NICE TA249 published in March 2012 recommended dabigatran (Pradaxa ) as an option for the prevention of stroke and systemic embolism within its licensed indication, that is, in people with nonvalvular atrial fibrillation with one or more of the following risk factors: Previous stroke, transient ischaemic attack or systemic embolism Left ventricular ejection fraction below 40% Symptomatic heart failure of New York Heart Association (NYHA) class 2 or above 75 years old 65 years old with one of the following: diabetes mellitus, coronary artery disease or hypertension. 1. Baseline assessment prior to initiation of dabigatran (Pradaxa ) 1.1 Baseline Activated Partial Prothrombin Time (aptt), International Normalised Ratio (INR), haemoglobin, urea & electrolytes and liver function tests 1.2 Weigh patient 1.3 Calculate baseline creatinine clearance (CrCL). The electronic calculator is available on the intranet 1.4 Establish bleeding risk for individual patient (See table 1) 1.5 Complete initiation checklist for dabigatran and file in patient records 1.6 Informed discussion with patient regarding risks and benefits of dabigatran (document this in the patients notes). This MUST include that there is currently no available antidote for reversing dabigatran in the event of a major bleed 1.7 Confirm if patient already taking other anticoagulants and switch according to Section 3 (document action taken in medical notes) 1.8 ALL patients MUST be given the dabigatran alert card. 2. Dose of dabigatran (Pradaxa ) - 150mg hard capsule orally twice daily. Therapy should be continued long term. Some patients require a lower dosage of dabigatran 110mg twice daily (See table 1 and 2). Dabigatran for stroke prevention in Atrial Fibrillation. Clinical Guideline V1. Page 1 of 6 Principal Authors; R. Curran & G. McKerrell, Pharmacists WUTH.

2 Table 1. Bleeding risks and recommended dosage adjustments Patient Factors If your patient has any of these MAJOR risk factors: Hypersensitivity to the active substance or to any of the excipients Severe renal impairment (CrCL < 30 ml/min) Active clinically significant bleeding or organic lesion at risk of bleeding High risk of falls that are likely to cause injury and contraindicate the use of anticoagulation Hepatic impairment or liver disease expected to have any impact on survival Concomitant treatment with systemic ketoconazole, ciclosporin, itraconazole & tacrolimus (see table 2) Breastfeeding and pregnancy Diseases/procedures with special haemorrhagic risks Congenital or acquired coagulation disorders Thrombocytopenia or functional platelet defects Active ulcerative GI disease Recent GI bleeding Recent biopsy or major trauma Recent Intracerebral haemorrhage Brain, spinal, or ophthalmic surgery Bacterial endocarditis If your patient has any of these increased AMBER bleeding risk factors: Age > 80 years old Age years when thromboembolic risk is low and bleeding risk high Weight < 50kg CrCL 30-50mls/min Concomitant treatment with interacting drugs see table 2 History of gastritis, oesophageal reflux disease and oesophagitis And all MAJOR risk factors have been excluded. If more than two AMBER risk factors reconsider the overall risk versus benefit of treatment with dabigatran Dose of dabigatran Avoid as contraindicated Initiate reduced dabigatran dose of 110mg twice daily If your patient is: Age years CrCL > 50mls/min Weight > 50kg And all major and additional risk factors for bleeding have been excluded as above Dabigatran for stroke prevention in Atrial Fibrillation. Clinical Guideline V1. Page 2 of 6 Initiate standard dabigatran dose of 150mg twice daily

3 3. Switching anticoagulants Dabigatran treatment to parenteral anticoagulant. It is recommended to wait 12 hours after the last dose of dabigatran before switching to a parenteral anticoagulant. If CrCL < 30mls/min wait 24 hours before initiating parenteral treatment. Parenteral anticoagulants to dabigatran Dabigatran should be given 0 to 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)). Dabigatran treatment to Vitamin K antagonists (VKA) e.g. warfarin. Adjust the starting time of the VKA based on CrCL as follows: CrCL 50 ml/min, start VKA three days before discontinuing dabigatran CrCL 30 - < 50 ml/min, start VKA two days before discontinuing dabigatran VKA to dabigatran Stop the VKA. Give dabigatran when the INR is < Monitoring There is no routine anticoagulant blood monitoring for dabigatran. For patients at risk of bleeding the aptt provides an approximate indication of the anticoagulant intensity achieved with dabigatran. This test has limited sensitivity and is not suitable for precise quantification of anticoagulant effect, especially at high plasma concentrations of dabigatran. High aptt values should be interpreted with caution. Dabigatran is a black triangle drug. ANY adverse effects must be reported to the Committee on Safety of Medicines (CSM) Renal Function Assess renal function at baseline and every six months thereafter. Close clinical supervision is required in patients with stage 3 chronic kidney disease (CKD) CrCL 30-60ml/min, e.g. monitor renal function every three months or more frequently if clinically appropriate. In clinical situations when it is suspected that renal function could deteriorate (such as hypovolemia, dehydration) and with certain co-medications (e.g. high dose diuretics) renal function should be assessed more frequently and the dose of dabigatran reviewed as appropriate Bleeding risk As with all anticoagulants, dabigatran should be used with caution in conditions with an increased risk of bleeding. Bleeding may occur at any site during therapy with dabigatran. An unexplained fall in haemoglobin and/or haematocrit or blood pressure should lead to an investigation to identify any potential bleeding site. Haemaglobin levels and blood pressure Dabigatran for stroke prevention in Atrial Fibrillation. Clinical Guideline V1. Page 3 of 6

4 should be monitored regularly throughout the treatment period, especially if risk factors are combined. 5. Problem Solving 5.1 Drug Interactions Table 2. Selected interactions and recommended dosage adjustments: (Refer to BNF/SPC for a full up-to-date list of interactions) Amiodarone and quinidine Verapamil Rifampicin, carbamazepine, phenytoin, St Johns Wort UFH, LMWH, heparin derivatives, thrombolytic agents (fondaparinux), GPIIb/IIIa receptor antagonists, dextran, sulphinpyrazone, rivaroxaban and vitamin K antagonists Dronedarone Clarithromycin Systemic ketoconazole, ciclosporin, itraconazole, tacrolimus Antiplatelets, NSAIDs, SSRIs and SNRIs. Digoxin Drug Interactions Plasma concentrations of dabigatran are increased so reduce dose to 110mg twice daily. Close clinical surveillance is required. Monitor for signs of bleeding or anaemia. Plasma concentrations of dabigatran are increased so reduce dose to 110mg twice daily. Close clinical surveillance is required. Monitor for signs of bleeding or anaemia. Dabigatran and verapamil should be taken at the same time. Plasma concentrations of dabigatran decreased. Avoid co-prescribing. Increased risk of GI bleeding. Caution if co-prescribed Use of thrombolytic agents for treatment of acute ischaemic stroke refer to Time is Brain pathway and consult with Stroke consultant on call. Inadequate clinical data. Avoid concomitant use. Plasma concentrations of dabigatran are increased. Close monitoring required in particular in renal impairment. Monitor for signs of bleeding or anaemia. Plasma concentrations of dabigatran are increased. Dabigatran is contraindicated. Increased risk of GI bleeding. Consider risk vs benefit and indications for treatment with both. Consider using the reduced dose of dabigatran 110mg twice daily No interactions reported to date Dabigatran for stroke prevention in Atrial Fibrillation. Clinical Guideline V1. Page 4 of 6

5 Beta - blockers Ritonavir and combinations No interactions reported to date Plasma concentrations of dabigatran are decreased. Coprescribing is not recommended 5.2. Acute Bleeding Please see the clinical guideline Dabigatran guideline for management of acute bleeding Surgery If an acute intervention is required, dabigatran should be temporarily discontinued. Surgery or 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 and this should be weighed against the urgency of intervention. Prior to elective surgical procedures and interventions temporarily discontinue dabigatran as there is an increased risk of bleeding. Clearance depends on renal function which will affect how long before the procedure to discontinue dabigatran. The table below can be used as a guide, but the opinion of the operating surgeon should be sought. Table 3. Stopping dabigatran prior to elective surgery. CrCL (ml/min) Estimated half-life (hours) Stop dabigatran before elective surgery High risk of bleeding or major surgery Standard risk of bleeding 80 ~13 2 days before 24 hours before 50 - <80 ~ days before 1-2 days before 30 - <50 ~18 4 days before 2-3 days before 5.4. Acutely unwell patients While on treatment with dabigatran renal function should be assessed in clinical situations where it is suspected that renal function could decline or deteriorate. Consider temporarily substituting dabigatran with prophylactic low molecular weight heparin in patients who are admitted to hospital with sepsis, acute kidney injury, hypovolaemia, dehydration or who are started on high dose diuretics. It is recommended to wait at least 12 hours after the last dose of dabigatran before starting parenteral anticoagulation Compliance Aids - Dabigatran capsules must be stored within the manufacturers original packaging (aluminium foil strips/bottles) to prevent physical instability. It is therefore not suitable for dispensing in compliance aids Swallowing difficulties - Bioavailability of dabigatran is increased if removed from the capsule. Patients should be instructed not to open the capsule as this may increase the risk of bleeding. Alternative agents should be used in patients with swallowing difficulties. Dabigatran for stroke prevention in Atrial Fibrillation. Clinical Guideline V1. Page 5 of 6

6 5.7. Overdose with dabigatran Overdose exposes the patient to an increased risk of bleeding. The aptt gives an indication of the bleeding risk and the patient should be closely monitored for signs of bleeding. There is no specific antidote for dabigatran overdose. Please refer to the clinical guideline Dabigatran Guideline for management of acute bleeding. 6. Patient information All patients should be given the dabigatran alert card and counselled on the details. This should be documented on the initiation checklist and filed in the patients medical notes. Patient understands the potential bleeding risks with dabigatran and is aware that there is currently no readily available antidote for its effects and the potential ramifications of this. All patients should be advised on what to do if they miss a dose of dabigatran: A missed dose of dabigatran 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 Dabigatran should be swallowed as a whole capsule with water, with or without food. Instruct patient not to open the capsule as this may increase the risk of bleeding. All patients should be counselled to inform their dentist or any other healthcare professional performing invasive treatments or surgery that they are taking dabigatran. 7. References Dabigatran etexilate for the prevention of stroke and systemic embolism in atrial fibrillation. NICE TA 249 (March 2012). Available from Summary of product characteristics for Pradaxa available online at British National Formulary 63, March 2012 Pradaxa patient alert card available at Dabigatran for stroke prevention in Atrial Fibrillation. Clinical Guideline V1. Page 6 of 6