Cardiology  |  Atrial Fibrillation Pathway - Comparison of Anticoagulant Options




Cardiology

Atrial Fibrillation Pathway - Comparison of Anticoagulant Options

Summary of properties of dabigatran and warfarin

AF = atrial fibrillation, INR = international normalised ratio, GI = gastrointestinal

Property

Dabigatran

Warfarin

Indication for AF

Non-valvular atrial fibrillation

Not to be used in those with mechanical heart valves

Valvular or non-valvular atrial fibrillation

Mechanism of action

Direct inhibition of thrombin

Reduced synthesis of prothrombin and other clotting factors

Administration

Oral

Twice daily (for AF)

Oral

Once daily

Dosing

Fixed dose, dependent on creatinine clearance and age.

Adjust to 110mg bd if:

  • Age>80 (some say 75)
  • Impaired renal function (CrCl 30-50ml/min)
  • Contraindicated if CrCl<30 

Individualised to each patient and target INR

Onset of action

0.5-2 hours

36-72 hours

Elimination half-life

12-14 hours

20-60 hours

Duration of action

24 hours

48-96 hours

Stable, predictable pharmacokinetics

Yes

No

Interactions with diet and alcohol

No

Yes

Interactions with medicines

Interactions largely unknown, clinical experience over time likely to reveal more.

The rise in drug availability with concomitant use with amiodarone or verapamil is not deemed clinically significant and dose adjustment is not required.

Avoid use with ketoconazole.

Multiple

Monitoring

No routine monitoring required.

If tests are used, timing of blood sample is important for correct interpretation.

INR every one to eight weeks depending on clinical situation

Risk of major haemorrhage

Similar for both medicines.

Major GI bleeding rates may be higher than with warfarin, however, rates of intracranial haemorrhage and life-threatening bleeding may be lower with dabigatran.

2015: At the higher dose dabigatran is as safe as warfarin and at least (if not more) efficacious. There is meta-analysis evidence of better outcomes 30 days after a major bleed with dabigatran than warfarin.

Similar for both medicines.

Other adverse effects

Dyspepsia occurs in up to 1/3 of patients, but may resolve itself after 2 weeks.

Possibly increased risk of MI.

Multiple reported, however, in clinical practice these are relatively rare

Antidote

None available but can be removed by dialysis.

Vitamin K
Fresh-frozen plasma

Cost

Fully funded

Fully funded

 

Other Therapies

Property

Rivaroxaban
(Xarelto)

Apixiban
(Eliquis)

Mechanism of action

Factor Xa inhibitor

Factor Xa inhibitor

Monitoring

Nil

Nil

Interactions

Theoretically less than dabigatran

Theoretically less than dabigatran

Dose

20mg od
Reduce to 10mg od if impaired renal function (CrCl 30-50)
Avoid if Cr Cl <30

 

Availability

Early access programme via drug company (not funded by Pharmac)

Early access programme from selected private cardiologists


Everything you should know about the new anticoagulants” 

 

 



Last updated : Friday, August 21, 2015
Next review date : Saturday, August 20,2016


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