A Keep it Simple Summary guide to the NOACS
You wait 50 years for a new anticoagulant to come along, and then 3 come along at once...with a fourth (Edoxaban) just round the corner.
For the last 5 years evidence has been emerging for the novel oral anticoagulants (NOACS) dabigatran, rivaroxaban and apixaban as an alternative to warfarin for the prevention of stroke and systemic embolism. All have been approved by NICE and the SMC as alternative options to warfarin.
This month NICE are to publish their updated guideline on Atrial Fibrillation and it is expected (in line with NICE draft AF Guideline 2014) that GPs will be able to prescribe all 3 on the NHS. It is also anticipated that for patients who are already taking warfarin that we will be encouraged to assess their TTR (time in the therapeutic range) and if this is <65% to consider switching warfarin to a NOAC.
We would argue that for the majority of patients warfarin should remain the first-line option. It has 50 years of clinical experience behind it, it is cheap, it is effective, we can tell if patients are actually taking it, it is safe if properly monitored and there is an antidote in case of haemorrhage.
However, many patients are likely to choose to have a NOAC for understandable reasons of convenience and there is a strong argument (improved efficacy) for switching to a NOAC if patients INR is not well controlled. So, we shall all be prescribing these drugs much more over the next few years. There are some important differences between them which will influence which is the most appropriate for your patient. We present our KISS NOAC guide to help you - this is a general guide, all doses should be checked & prescribing should be guided by an appropriate national formulary such as The BNF
However, many patients are likely to choose to have a NOAC for understandable reasons of convenience and there is a strong argument (improved efficacy) for switching to a NOAC if patients INR is not well controlled. So, we shall all be prescribing these drugs much more over the next few years. There are some important differences between them which will influence which is the most appropriate for your patient. We present our KISS NOAC guide to help you - this is a general guide, all doses should be checked & prescribing should be guided by an appropriate national formulary such as The BNF
Note that all 3 of these NOACs share the following:
· They are licensed for the prevention of stroke and systemic embolism in
patients with non-valvular AF with one or more of the following risk factors
o
Prior CVA or TIA
o
Age over 75
o
Symptomatic heart failure
o
Hypertension
o
DM
·
Contraindications
o
Active clinically significant
bleeding or significant risk of major bleeding
o
Pregnancy and breast feeding
o
Additional anticoagulant
therapy (extreme care and specialist advice with antiplatelet therapy)
o
Concomitant therapy with
ketoconazole, itraconazole and HIV protease inhibitors
All patients need to be warned re bleeding risk and to get medical advice ASAP if bleeding occurs. They also need to be reminded on the crucial importance of compliance, as efficacy will quickly drop if tablets are missed. They all share a very high cost, which is likely to be subject to some regional variation but is approximately £800 per annum.
Differences between the NOACs
Dabigatran
|
Rivaroxaban
|
Apixaban
|
|
Mechanism
|
Direct thrombin inhibitor
|
Factor Xa inhibitor
|
Factor Xa inhibitor
|
Time
to peak levels
|
3
hours
|
3
hours
|
3
hours
|
Half-life,
h
|
12-17
|
5-13
|
9-14
|
Excretion
|
80% renal (avoid then if renal problems)
|
66% liver, 33% renal (avoid then with liver disease)
|
|
Dose
|
150mg bd (110mg bd if aged over 80)
|
20mg od (same dose in elderly)
|
5mg bd (2.5mg bd if age over 80 and under
60kg)
|
Dose
in renal impairment
|
110mg bd if egfr 30-50, contraindicated
if eGFR <30
|
15mg od if eGFR 15 to 50, not recommended
if eGFR <15
|
2.5mg bd if eGFR 15-29, not recommended
if eGFR <15
|
Interactions
|
PPIs may impair absorption
Avoid enzyme inducers &
ciclosporin/tacrolimus
Increased bleeding risk with verapamil,
amiodarone, quinidine, ketoconazole, SSRI, SNRI & clarithromycin
|
Enzyme inducers (e.g. rifampicin,
phenytoin, carbamazepine etc) reduce efficacy
Avoid dronaderone & voriconazole
|
Enzyme inducers (e.g. rifampicin,
phenytoin, carbamazepine etc) reduce efficacy
Avoid voriconazole
|
Administration
|
Swallow whole , opening capsules may
increase bleeding risk
Dyspepsia more commonly reported than with warfarin & the other NOACs
|
Take with food
|
No special directions
|
Helping patients to decide
NICE have produced a decision aid to help patients choose between the different anticoagulant options
NICE NOAC decision aid for patients
Simon Curtis
NICE have produced a decision aid to help patients choose between the different anticoagulant options
NICE NOAC decision aid for patients
