Anticoagulation CBL Flashcards by Hannah Williams

What are the 3 types of stroke?

Transient embolic stroke
Cardioembolic
Haemorrhagic stroke

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What is the CHADS2 score?

To determine risk of cardioembolic stroke only in AF patients

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What does CHADS2 stand for and how many points are associated with each?

Congestive heart failure = 1
Hypertension = 1
Age at least 75 years = 1
Diabetes = 1
Stroke/TIA/thromboembolism previously = 2

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What is the CHA2DS2VASc score and a benefit of it?

Updated version

Better stratification of low risk patients

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What does CHA2DS2VASc stand for and how many points are associated with each?

Congestive heart failure = 1
Hypertension = 1
Age at least 75 years = 2
Diabetes = 1
Stroke/TIA/thromboembolism previously = 2
Vascular disease (e.g. MI, peripheral artery disease) = 1
Age 65-74 years = 1
Sex category (female) = 1

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Why might the % scores differ in the CHAD?

According to different studies and different populations

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Taking anticoagulation treats AF. True or false?

False- only reduces risk of future events

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What is the purpose of antiembolic compression stockings?

Promotes circulation and reduces DVT risk

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What is the MOA of warfarin?

Inhibits hepatic production of Vitamin K dependent coagulation factors 2, 7, 9 and 10 via Vitamin K epoxide reductase

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What happens if someone has hepatic impairment and is taking warfarin?

Warfarin builds up

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What is a side effect of warfarin?

Bleeding

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What is a disadvantage of taking warfarin?

Monitoring requirements due to narrow therapeutic index, and dose changes regularly. Huge inter-patient variability

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What is the antidote for warfarin?

Vitamin K

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What is the INR target in AF?

2-3

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How is warfarin metabolised?

CYP450

2C9 and 3A4

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Why do macrolides interact with warfarin?

CYP450 inhibitor
Macrolide decreases warfarin metabolism
Increased risk of bleeding

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Warfarin and aspirin interact. True or false?

True- increases bleeding risk

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Patients sometimes take garlic capsules for heart health and circulation. What is the problem with them?

Increased risk of bleeding

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How would you start warfarin therapy in AF?

Loading dose to reduce time to steady state
5-10 mg OD on day 1, which may need to be lowered in the elderly
Start slow and titrate up until INR target has been reached
Monitor a few days after the first dose as warfarin has a long half life (40 hours)
Once INR is stable, monitoring can be reduced to every 12 weeks
Dose taken at same time each day

What do you need to monitor when on warfarin?

INR

Hepatic and renal function

Name DOACs

Apixaban
Rivaroxaban
Dabigatran

What is the advantage of DOACs?

Less monitoring required compared to warfarin

What are the disadvantages of DOACs?

Possible adherence issues due to less monitoring requirements
More expensive
Does not have an antidote

Why does aspirin and DOACs interact?

Increased bleeding risk

What is the mechanism of action of apixaban and rivaroxaban?

Inhibits free and bound factor 10a which interrupts extrinsic and intrinsic pathway This inhibits thrombin formation and development of thrombi

What is the MOA of dabigatran?

Inactive prodrug converted in the plasma and liver to active drug Competitive direct reversible inhibitor of thrombin (factor 2a) to prevent thrombus development

Should anticoagulation therapy for AF be life long?

Yes

What procedures can sometimes reverse AF? What are the disadvantages of these?

Cardioversion and ablations, however they tend to fail after a while. The patient needs to be anticoagulated before, during and a set time after procedure until sinus ryhthm

If a patient has had a STEMI in the past and have now been diagnosed with AF, they may be on triple therapy. What drugs are in this regimen and how would it differ from dual antiplatelet therapy?

Warfarin Aspirin Clopidogrel One of the platelets e.g. clopidrogrel would be used for a shorter duration (3 months) rather than 12 months

What tests would you do to diagnose a PE?

- D-dimer test - formed from the thrombin cascade - Chest x ray to rule out differential diagnosis - Pulmonary angiography - Computer assisted pulomonary topography

What is a rare side effect of heparins?

Heparin induced thrombocytopenia

What is the benefit of anticoagulation in a blood clot?

It will not get rid of the clot but it will stop it from getting bigger

In what situation would you thrombolyse a patient?

Massive PE

What is first line for a PE?

LMWH e.g. enoxaparin, dalteparin Warfarin is initiated at the same time as heparin. INR monitoring and after is has been 2 for 24 hours, then the LMWH can be stopped. Usually, takes about 5 days 5-10mg OD on first day then dose is adjusted

What are the advantages of LMWH compared to heparin?

Less monitoring required Can give OD/BD subcut doses rather than continuous infusion

In what case might a LMWH not be appropriate when treating a PE? What would you give in this case?

- Severe renal imapirment CrCl< 15 mL/min as it is renally cleared - You would give unfractionated heparin (would also give it in NSAID induced renal failure)

How would you give unfractionated heparin in PE and what monitoring is required?

- Loading dose followed by continuous infusion | - Daily monitoring of APTT (activated partial thromboplastin time)

What are the causes of DVT and PE?

- Pregnancy - Oral contraceptive (POP not so much) - Travel- long haul flights - HRT - Recent orthopaedic surgery

What is the length of anticoagulation therapy following a PE?

1st episode + know the cause (provoked) = 3-12 month therapy Unprovoked/second episode/not being able to eliminate the risk factor  longer term with reviews If unprovoked, patient needs to be investigated for undiagnosed cancer through a variety of tests e.g. chest x-ray, blood tests, urine tests Has patient responded to therapy? E.g. for a DVT, has leg swelling gone down?

What would a patient need to carry around with them if on warfarin?

Yellow dosing book

Which DOACs are heparin leading and which ones aren't?

Apixaban and rivaroxaban are not heparin leading Dabigatran is heeparin leading (treatment dose of LMWH dor 5 days prior to starting DOAC)

What should you do if a patient comes into the pharmacy for a warfarin prescription without their yellow book?

- Should not give out warfarin without knowing the patient is having frequent INR monitoring as recommended by the NPSA - Contact GP/warfarin clinic - If overdue for monitoring, should not be giving them warfarin. However, you need to consider what’s in the best interest of the patient. If they couldn’t go to last appointment, constantly stable and INR does not vary, you can give them a few days worth and recommend they see INR clinic ASAP

What is an important thing to remember when dispensing warfarin in terms of tablets given out?

Make sure that patient has combination of all different strengths of warfarin as dose is constantly changing

Why aren't 0.5 mg warfarin tablets used as much?

They are plain white and could be mistaken for other medication

What colour are 1mg warfarin tablets?

Brown

What colour are 3mg warfarin tablets?

Blue

What colour are 5mg warfarin tablets?

Pink