1 Prescribing Points A NEWSLETTER FOR ALL HEALTH CARE PROFESSIONALS IN OXFORDSHIRE, WRITTEN BY THE MEDICINES MANAGEMENT TEAM, OXFORDSHIRE PCT, JUBILEE HOUSE, OXFORD BUSINESS PARK SOUTH, OXFORD, OX4 2LH. Date of issue: June 2012 (updated November 2012 following NICE TA 256) VOLUME No: written by Sara Wilds & Kathryn Buchanan. Oxfordshire CCG Statement on the use of Dabigatran ( Pradaxa ) and Rivaroxaban ( Xarelto ) in the Prevention of Stroke and Systemic Embolism in Adult Patients with Non valvular Atrial Fibrillation In March 2012 NICE issued final guidance (TA249) supporting the use of dabigatran etexilate as an option for the prevention of stroke and systemic embolism, in people with non-valvular atrial fibrillation (AF) 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 of age 65years with one of following: diabetes mellitus, coronary artery disease or hypertension The guidance also recommends that the decision about whether to start treatment with dabigatran should be made after an informed discussion about the risks and benefits of dabigatran compared with warfarin. Rivaroxaban followed with similar guidance in May 2012 (TA256). Having considered NICE s recommendation, in the context of the potential risks vs. benefits and the continuing significant implications for the local health economy, APCO recommends that:- Warfarin remains the agent of choice for most patients in atrial fibrillation (AF) stroke prevention Patients currently stable on warfarin therapy should not be considered for a switch to NOACs. The focus of AF management should be on identifying patients with AF and undertaking stroke risk assessment using the CHADS 2 risk assessment tool. Patients with a CHADS 2 or CHA 2 DS 2 VASc score 1 should be considered for initiation of appropriate anticoagulation therapy. New oral anticoagulants (NOACs) should be considered as an alternative to warfarin for stroke prevention in AF in patients who: have a warfarin allergy or a specific contraindication to warfarin therapy or are unable to comply with the monitoring requirements of warfarin. Non-compliance alone is not an indication for initiating therapy with a NOAC as many of the causes of noncompliance may also result in non-compliance with NOACs. It is of concern that there is no specific antidote. If using a NOAC for AF, dabigatran is the preferred choice but there may be instances where rivaroxaban is preferred (p4) Both licensed NOACs have different contra-indications (renal & hepatic impairment) and interactions which must be considered before prescribing. Refer to SPCs for detail. Poor compliance on warfarin is a contraindication to NOACs due to rapid recovery of coagulation This statement will be reviewed a minimum of annually, to take account of growing clinical experience and the publication of national guidance on the other NOAC (Apixaban). This statement should be read in conjunction with the dabigatran (Pradaxa) and rivaroxaban (Xarelto) summary of product characteristics (www.medicines.org.uk) All suspected adverse reactions should be reported to the MHRA via the yellow card scheme yellowcard.mhra.gov.uk/
2 Groups of patients for whom an alternative OAC may be appropriate There may be some patients who fulfil the NICE criteria above and an alternative to warfarin would be desirable. The main groups currently suggested are as follows: Those with proven intolerance to warfarin, acecoumarol and phenindione (rare) For short term use prior to and after cardioversion/catheter ablation, but only if the patient can discontinue anticoagulation if sinus rhythm is restored following the procedure. This is unlikely to be the case, unless the cause of the AF has been treated and is not expected to recur Frequent travellers: If the logistics of attending the surgery for regular blood tests is the barrier to starting warfarin, also could consider self testing with Coagucheck (still managed via RAID). Difficult venepuncture: In some cases dabigatran may offer a useful alternative. Remember that blood tests will still be required occasionally as it will be important to monitor e.g. renal function Those on multiple interacting drugs where it has not been possible to stabilise the INR within the first 3 months of treatment. Seek specialist advice if unsure. Where patients are monitored via the Anticoagulation Service, GPs are advised to contact the Anticoagulation Service nurses to discuss the stability of individual patients For patients eligible for oral anticoagulation with no prior warfarin use in who stable INR control is unlikely or bleeding risk is intermediate or high (on specialist advice only) Patients who are fully informed of the potential disadvantages of dabigatran but refuse to take Warfarin (refer to appendix 2). Important considerations on the use of dabigatran and for stroke prevention in AF: 1. Any patient with a risk of falls is at high risk of haemorrhagic complications with any anticoagulant. Dabigatran is not an alternative if warfarin is deemed to be unsuitable for a high falls risk patient. 2. A number of cases of serious and fatal haemorrhage have been reported in elderly patients with renal impairment who were receiving dabigatran. Renal function should be assessed in all patients before starting dabigatran and at least once a year in patients older than 75 years or those with a suspected decline in renal function. (see:http://www.mhra.gov.uk/safetyinformation/drugsafetyupdate/con137771) 3. There is currently no licensed, readily available antidote to dabigatran, which may have significant implications for patients in cases of accidental overdose or where emergency surgery is required (within a period of 12 hours from the last dose of dabigatran). 4. Close monitoring (for signs of anaemia or bleeding) is advised in patients with the following factors: Age 75 years (Refer to SPC and Note dose of 110mg twice daily advised 80 years). Low body weight (<50kg). Moderate renal impairment (30 to 50mL/minute/1.73m2 egfr) Note contraindications. Concurrent treatment with antiplatelets, NSAIDs, SSRIs, amiodarone, verapamil (Note 110mg twice daily should be used in patients co prescribed verapamil), quinidine, ketoconazole and clarithromycin Also note Contraindications. Individuals at increased haemorrhagic risk (initiated on specialist advice only) 5. Contraindications to dabigatran Hypersensitivity to the active substance or to any of the excipients. Patients with egfr < 30ml/min Active clinically significant bleeding. Organic lesion at risk of bleeding. Spontaneous or pharmacological impairment of haemostasis. Hepatic impairment or liver disease expected to have any impact on survival. Concomitant treatment with systemic ketoconazole, ciclosporin, itraconazole and tacrolimus Prosthetic heart valves requiring anticoagulant treatment - increased bleeding & thromboembolic events seen in phase II trials. The SPC advises that dabigatran should not be used during pregnancy unless clearly necessary.
3 6. Dose The recommended dose of dabigatran is 150mg twice daily. A reduced dose of 110mg twice daily is appropriate for; those aged 75 to 80 years with a lower thromboembolic risk and a higher bleeding risk (see SPC), those aged 80 years or above and those concurrently taking verapamil (Refer to SPC for full details). 7. Main adverse effects Bleeding events, anaemia, haematoma, haematuria and dyspepsia 8. Main interacting medicines: NSAIDs in combinations with dabigatran increase the risk of bleeding and close observation is required. Amiodarone, verapamil, quinidine, ketoconazole and clarithromycin can increase dabigatran plasma concentrations. Rifampicin, carbamazepine, phenytoin, and St Johns Wort can decrease dabigatran plasma concentrations. 9. Points to note about the pivotal RE LY study (designed to show 110mg and 150mg twice daily dabigatran were non inferior, in terms of preventing stroke/systemic embolism and rates of major haemorrhage, to adjusted dose warfarin): The high dose dabigatran (150mg bd) was shown to slightly reduce the stroke risk compared to warfarin (NNT 167 over 1 year) with similar rates of major bleeding The low dose dabigatran (110mg bd) was shown to reduce the risk of major bleeding compared with warfarin but there was no difference in the risk of stroke The dabigatran treated groups experienced higher rates of dyspepsia compared to the warfarin treated groups Note dose of 110mg twice daily should be considered for patients with gastritis, esophagitis, or gastroesophageal reflux. Serious adverse events leading to discontinuation occurred more frequently with both doses of dabigatran (both 2.7%) than with warfarin (1.7%; P<0.001; NNH 100) 10. Long term safety data (i.e. beyond 2 years) is not yet available for continuous dabigatran. 11. Dabigatran requires twice daily dosing compared to warfarin s once daily regime. 12. Dabigatran capsules must be retained within their original packaging until the point of administration so are NOT suitable for re packaging into monitored dosage systems. 13. A year s treatment with dabigatran costs 803 (this price was reduced from 920 in April 2012). Warfarin drug costs are less than 15 per year. 14. Use of Dabigatran in the primary prevention of venous thromboembolic events in elective total hip or knee replacement surgery remains red (specialist only) traffic light status across Oxfordshire. How to switch from warfarin to dabigatran (only if poorly controlled) Dabigatran etexilate can be given as soon as the International Normalized Ratio (INR) is < 2.0. How to switch from dabigatran to warfarin e.g. if not tolerated due to nausea Adjust the starting time of the VKA based on CrCL as follows: CrCL 50 ml/min, start VKA 3 days before discontinuing dabigatran etexilate CrCL 30-< 50 ml/min, start VKA 2 days before discontinuing dabigatran etexilate
4 Important considerations on the use of rivaroxaban for stroke prevention in AF: NICE TAG 256 (May 2012) recommended rivaroxaban 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 risk factors such as: congestive heart failure hypertension age 75 years or older diabetes mellitus, prior stroke or transient ischaemic attack. The same principles agreed by OCCG for dabigatran in stroke prevention in AF apply to rivaroxaban, but some of the differences are outlined below. (Note that the trials compared different levels of INR rates TTR was 64% in RE-LY and 55% in ROCKET AF) Efficacy in stroke prevention compared to warfarin Reduced risk of bleeding compared to warfarin Dabigatran Overall no difference Superior (150mg bd dose) Non-inferior (110mg bd dose) Evidence for reduced bleeding risk at lower dose. NB Increased risk of GI bleed than warfarin at higher dose which is the usual dose. Overall reduced intra cranial haemorrhage (ICH) Rivaroxaban Overall no difference Non inferior (ITT analysis) Equivalent to warfarin (except reduced ICH) Renal function c/i if CrCl <30ml/min Use in caution if CrCl 15-49ml/ min. Reduced dose 15mg od Reversibility Uncertain. Uncertain (possible data supports use PCC which may reverse the laboratory abnormalities of clotting but this may not translate into stopping the actual bleeding event) Dialysable Yes, but will need to be carried No out for at least 6 hours in order to ensure adequate drug clearance Dosing bd od Drug interactions P- glycoprotein substrates Simultaneous PGP & CYP-3A4 Drug cautions (increased bleeding Antiplatelet agents, NSAIDs, Antiplatelet agents, NSAIDs risk) SSRIs or SNRIs Use in patients with swallowing difficulties Cannot be crushed May be crushed and put through NG tube Suitability for MDS Not suitable Suitable Cost / year Although dabigatran remains the preferred NOAC in SPAF, rivaroxaban may have advantages over dabigatran where an MDS is required CrCl 15-29ml/min a reduced dose of 15mg od is licensed although still has a caution in use (Dabigatran contra-indicated if CrCl is less than 30ml/min
5 Information which may be useful in discussion with patients Potential advantages of warfarin over dabigatran Patients with good INR control using warfarin may achieve slightly better health benefits than those using dabigatran, i.e. the benefits of dabigatran diminish with improving INR control. It is much easier to manage major bleeding with patients on warfarin. The anticoagulant effect of warfarin is easier to measure and rapid reversal can be achieved with vitamin K and prothrombin complex concentrates. There is currently no licensed product available to rapidly reverse dabigatran. INR monitoring enables assessment of compliance with warfarin. Dabigatran is not monitored routinely but does affect coagulation tests and their interpretation. However this does not lend easily to assessment of compliance. Patients with poor compliance may be at greater risk of thromboembolic complications with dabigatran as its shorter half life (it is BD dosing) will potentially result in more time without any degree of anticoagulation. Rates of GI bleeding and GI symptoms (in particular nausea) are greater with dabigatran, particularly with the 150mg bd dose in patients > 75 years. The safety profile of dabigatran is still not totally understood and there is no long term safety data. There is limited knowledge of use in dabigatran in certain patient groups e.g. extremes of body weight, renal or hepatic impairment, women of childbearing potential. Warfarin is tried and tested, having been in clinical use for almost 60 years 167 patients need to be treated with dabigatran rather than warfarin to save 1 additional stroke this will cost an extra 167,000 over the current warfarin costs. Potential advantages of dabigatran over warfarin In the RE-LY clinical trial, high dose dabigatran (150mg bd) has been shown to slightly reduce the risk of stroke compared with warfarin with similar rates of major bleeding In the RE-LY clinical trial, low dose dabigatran (110mg bd) has been shown to reduce the risk of major bleeding compared with warfarin but there was no difference in the risk of stroke However it is important to note that the relative risk of major bleeding with dabigatran, compared to warfarin, increases with age. Relative risk was highest in patients > 75 years There is no need for anticoagulant monitoring The dose regime is less complicated however there are still 2 different doses available, dose dependent on age and co-morbidities A more stable level of anticoagulation is achieved (if compliant) There are fewer potential interactions with other medication, alcohol and diet. However in patients taking verapamil, the dose of dabigatran should be reduced to 110mg bd (refer to SPC for full prescribing information) There is a rapid onset of action (2-4 hours after first dose). Use with caution post surgery. There is a rapid offset of action. Therapeutic effect lost within hours post dose.
6 Frequently asked questions What is dabigatran and what is it used for? Dabigatran is an anticoagulant (blood thinning medicine) used to reduce the risk of blood clot formation in patients with atrial fibrillation (an abnormal heart beat) and additional stroke risk factors. A blood clot causing a blockage in an artery is called an embolism. If the embolism occurs in the arteries of the brain it can cause a stroke. Anticoagulants are used to reduce the risk of these events happening. Will all patients currently on warfarin be switched to dabigatran? No; not all patients will be suitable for dabigatran. Dabigatran has only been studied in people with non -valvular atrial fibrillation (when the heart rhythm is abnormal, but the heart valves are healthy) and people with a medium to high risk of having a stroke. It is only approved for use in patients with nonvalvular atrial fibrillation. People who are on warfarin for other reasons; for example, they have had a clot in their leg or lung, or have a mechanical heart valve, cannot be considered for treatment with dabigatran and will need to continue on warfarin. I am on warfarin because I have non-valvular atrial fibrillation, is it worth changing? Warfarin has been prescribed for over 60 years so there is plenty of experience of its clinical use. If you are well controlled on warfarin then it is probably not advisable to change. The information from the clinical trial demonstrated that when warfarin was used well, it was as effective as dabigatran; and if anticoagulant control was good (as measured by blood tests), warfarin seemed to perform better overall. For patients who have poor anticoagulant control then a switch to dabigatran might be considered. I have just been diagnosed with atrial fibrillation and am due to start warfarin, is it better to go straight to dabigatran? The majority of people do well on warfarin so there would be no reason to use dabigatran initially. Dabigatran might be considered if there were subsequent problems with your anticoagulant control; for example, you have had difficulty getting the full benefit of warfarin therapy, allergy or intolerable side effects to warfarin and other coumarins. Is dabigatran better but simply too expensive to use? The advice within the consensus statement is about the safe and effective use of dabigatran, not its cost. While there are groups that will benefit from dabigatran, the vast majority of patients with atrial fibrillation probably will not. More strokes might be prevented in patients with atrial fibrillation by making sure that patients with a moderate to high risk of having a stroke are identified and warfarin prescribed well. Does dabigatran cause less bleeding than warfarin? As dabigatran and warfarin affect blood clotting, most side effects are related to signs such as bruising and bleeding. Intracranial bleeding (bleeding into the brain) is worrying because it is usually very serious but gastrointestinal (stomach and bowel) bleeding is a bigger concern because it is more common. Dabigatran does seem to cause less intracranial bleeding than warfarin but increases gastrointestinal symptoms (e.g. indigestion, stomach ache) and more seriously, gastrointestinal bleeding, particularly in those over 75 years of age. If you are over 75, or have an increased bleeding risk your doctor may only prescribe dabigatran at a reduced dose or may not prescribe at all. If I have excessive bleeding, can the anticoagulant effect of dabigatran be reversed? Unlike warfarin, there is not a licensed product currently available to reverse the effect of dabigatran.
7 Dabigatran does not need to be monitored; this is surely an advantage? This will be an advantage for some but may be a disadvantage for others. We cannot easily monitor its effect which means that we cannot easily know if it is working. It may also be a problem in the elderly with reduced kidney function as this can increase the risk of bleeding. The dabigatran dose will have to be reduced in certain patient groups, for example, the elderly, those with kidney disease and those on some other medicines. Will dabigatran interact with my other medicines, food or alcohol? It has fewer potential interactions with other medicines compared with warfarin, and at present there are no known interactions with specific foods or alcohol. There are some medicines that dabigatran does interact with. Tell your prescriber the names of all the medicines you are taking (including prescription and over-the-counter medicines, vitamins and herbal supplements) so that they can consider all potential interactions. Should I stop taking dabigatran if I m going to have a dental or medical procedure? Dabigatran may need to be stopped, if possible, for one or more days before any surgery, dental or medical procedure. Do not stop taking dabigatran without first talking to the doctor who prescribes it Management of bleeding in emergency situations for patients treated with Dabigatran There is no specific antidote to dabigatran. In the event of haemorrhagic complications, treatment must be discontinued and the source of bleeding investigated. Since dabigatran is excreted predominantly by the renal route adequate diuresis must be maintained. Appropriate supportive treatment, such as surgical haemostasis and blood volume replacement, should be undertaken at the prescriber s discretion. As protein binding is low, dabigatran can be dialysed; there is limited clinical experience to demonstrate the utility of this approach in clinical studies. Lack of a readily available method to determine the degree of anticoagulation creates a major challenge to those treating injured patients and local ED/trauma centres will need to agree local protocols to address this. Cost Impact for OCCG Dabigatran cost per patient per annum approx 803 Warfarin (3mg) cost per patient per annum approx 15 The cost impact of this new drug (purely prescribing costs) will be determined by the level of use. Current Oxfordshire figures show around 60% of AF patients (total 9916 patients) are on warfarin. An estimated 15% of these will have a contra indication to any OAC. This leaves potentially 25% who could potentially request dabigatran if it is indeed there as an equivalent 1 st line option with a prescribing cost impact of just under 2million per annum. This does not include patients who could request a switch from warfarin to dabigatran. So What? Practices should ensure that all prescribers are aware of the local Oxfordshire guidance for the prescribing of the new oral anticoagulant dabigatran in atrial fibrillation. Warfarin remains first line choice for most patients. It is important that each practice agrees their practice policy on the prescribing of dabigatran to ensure safe, equitable and cost effective prescribing.