Chapter 2: Anticoagulants Flashcards

1
Q

How do you assess patients with AF?

A
  1. CHA2-DS2-Vasc scoring tool: assesses the risk of stroke in patients with AF.
  2. HASBLED scoring tool: estimates the risk of major bleeding for patients on anticoagulation to assess risk-benefit in AF.
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2
Q

What is the maximum total score that can be given in the CHA2-DS2-Vasc and HASBLED tool?

A

9

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3
Q

What does CHA2-DS2-Vasc mean and the point allocation?

A

C: congestive heart failure or left ventricular dysfunction= 1 point
H: HTN = 1 Point
A: Age > or equal to 75= 2 points
D: diabetes mellitus= 1 point
S: stroke/ TIA/systemic arterial embolism = 2 points
V: vascular disease (peripheral arterial disease, previous MI, aortic plaque) = 1 point
A: age 65-74 = 1 point
S: sex= male (0), female (1)

Max total score: 9

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4
Q

What does HASBLED mean and the point allocation?

A
H: HTN = 1 point
A: Abnormal liver function = 1 point
     Abnormal renal function= 1 point
S: stroke = 1 point 
B: History of major bleeding = 1 point 
L: liable INRs: 1 point 
E: elderly (age > or equal to 65) = 1 point
D: drugs or alcohol, drugs- other antiplatelet agents or NSAIDS, alcohol abuse = drugs(1) alcohol (1)

Total max score= 9

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5
Q

What treatment is needed if patient has CHA2-DS2-Vasc SCORE of 0, OR female scoring 1?

A

Anticoagulation for stroke prevention is not indicated

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6
Q

What treatment is needed for a male with the CHA2-DS2-Vasc score of 1?

A

Consider anticoagulation accounting for bleeding risk

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7
Q

Is treatment needed for patients (men and women) with a CHA2-DS2-VASC score of 2 or more?

A

Yes, initiate anticoagulants accounting for bleeding risk.

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8
Q

How long does it take for vitamin K antagonist (VKA) such as warfarin, acenocoumarol and phenindione anticoagulant effect to fully take effect?

A

48-72 hours

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9
Q

What conditions have the target INR of 2.5?

A
AF
Antiphospholipid syndrome 
Bioprosthesis in the mitral position 
Calf vein thrombosis 
Cardiomyopathy 
DVT
PE
Cardioversion (higher targets such as 3, can be used for up to 4 weeks before the procedure)
Recurrent VTE or PE when no longer on VKA
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10
Q

What conditions have a target INR of 3.5?

A

Recurrent DVT or PE in patients receiving anticoagulation and have INR above 2.

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11
Q

What are the contra-indications in patients taking VKA?

A

Patients with haemorrhagic stroke or clinically significant bleeding.
Avoid within 72 hours of major surgery.
Avoid in pregnancy and within 48 hours postpartum.

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12
Q

Monitoring requirements for VKA?

A

Baseline LFTs, FBC and clotting screen (prothrombin time and INR).

In the early days of treatment, INR Should be measured OD or on alternate days, then longer intervals and eventually up to every 12 weeks depending on response.

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13
Q

What advice should be given if a patient missed a dose of the VKA?

A

Doses should be taken everyday at the same time.

Usually advised to take at 6pm so that any changes in the warfarin dose can be implemented on the same day.

Patients have up to MIDNIGHT to take a dose.

NEVER DOUBLE DOSE.

Record any missed doses in the yellow book.

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14
Q

What do you do if patient has an INR of 5-8 with no bleeding?

A

Withhold 1 or 2 doses of warfarin and lower the maintenance dose.

Restart warfarin at a lower dose once INR is in range

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15
Q

What do you do if a patient has an INR > 8 with no bleeding?

A

Stop warfarin.
Give phytomenadione (Vit K1) orally using the IV preparation.
Repeat if vit k1 if INR is still high after 24 hours.
Restart warfarin when INR is less than 5.

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16
Q

What do you do if a patient has minor bleeding and INR 5-8?

A

Stop warfarin.
Give Vit K1 by slow IV injection.
Restart warfarin when INR < 5.

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17
Q

What do you do if a patient has major bleeding?

A

Stop warfarin.
Give vit k1 by slow IV injection and give dried prothrombin complex;
If dried prothrombin complex is unavailable, fresh frozen plasma can be given but it’s not as effective.

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18
Q

What do you do if a patient has an INR > 8 with minor bleeding?

A

Stop warfarin.
Give Vit K1 by slow IV injection;
Repeat dose if INR is still high after 24 hours.
Restart warfarin when INR < 5.

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19
Q

What are the MHRA/CHM safety information on warfarin?

A
  1. Calciphylaxis (rare): report to GP if patients develop painful skin rash. More common in patients with end stage renal disease.
  2. Direct antivirals to treat hep C: risk of interaction and change INR.
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20
Q

What are DOACS and list examples

A

Direct oral anticoagulants
Direct inhibitors of activated factor Xa: apixaban, rivaroxaban, endoxaban.
Direct thrombin inhibitor with rapid onset of action: dabigatran.

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21
Q

What is the additional drug action of endoxaban compared to apixaban and rivaroxaban?

A

It’s a direct AND reversible inhibitor of activated factor Xa, which prevents conversion of prothrombin to thrombin and prolongs clotting time, thereby reducing the risk of thrombus formation.

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22
Q

What are the advantages of DOACS?

A
Fixed dose 
Predictable anticoagulant effect
Frequent monitoring is not needed
No dietary interactions
Fewer interactions with medications
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23
Q

What are the disadvantages of DOACS?

A

Short half life: rapid fall in effect if missed dose

Only dabigatran has a reversal agent: Idarucizumab (Praxbind)

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24
Q

What conditions are apixaban indicated for?

A

Stroke prevention in non-valvular AF.

Prevention of thromboembolism post total knee knee and hip replacement.

Treatment of DVT and PE

Prevention of recurrent DVT and PE

Available as 2.5mg and 5mg tablets

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25
Q

What are the contra-indications of apixaban?

A

Active bleeding; significant risk of major bleeding (e.g. recent GI ulcer, oesophageal varices, recent intracranial haemorrhage, maligant neoplasms)

Avoid with CrCl < 15ml/min

NOT licensed for the use in patients with prosethetic heart valves.
SEVERE LIVER DISEASE.
Use with caution in patients with elevated hepatic enzymes.

26
Q

What are the monitoring requirements of apixaban?

A

Baseline activated partial prothrombin time (aPTT), haemoglobin, U&E, LFTs, CrCl.

Reduce the dose in patients with CrCl 15-29ml/min.

Avoid if CrCl is less than 15ml/min.

Monitor for signs of bleeding or anaemia. Stop treatment if severe bleeding occurs.

27
Q

What is the apixaban dose for the prophylaxis of VTE post total knee and hip replacement?

A

CrCL > 30ml/min

KNEE: 2.5mg BD for 10-14 days. Start 12-24 hours after surgery.

HIP: 2.5mg BD for 32-38 days. Start 12-24 hours after surgery.

CrCl 15-29= use with caution

28
Q

What is the apixaban dose for the treatment of DVT or PE?

A

CrCl > 30ml/min:

Initially 10mg BD for 7 days, then 5mg BD for maintenance.

29
Q

What is the apixaban dose for the prophylaxis of recurrent DVT and PE?

A

2.5mg BD

Following completion of 6 months anticoagulant treatment

30
Q

What is the apixaban dose for the prophylaxis of stroke and systemic embolism in non-valvular AF?

A

CrCl 15-29ml/min= 2.5mg BD

CrCl > 30ml/min= 5mg BD
(reduce to 2.5mg BD in patients with 2 or more of the following: age 80 or over, weight < 61kg, or serum creatinine > or equal to 133micromol/L).

31
Q

What to do if a patient missed a dose of apixaban?

A

Take as soon as remembered, event if it means taking total daily dose at the same time.

Patients should continue dosing the next day.

32
Q

What are the adverse effects of apixaban?

A

An unexplained fall in haemoglobin and/ or haematrocrit or BP should lead to investigation to identify bleeding site.

Nausea, bruising, anaemia, skin reactions, Haemorrhage

33
Q

What conditions are endoxaban indicated for?

A

Stroke prevention in adult patients with non-valvular AF.
Treatment of DVT and PE
Prevention of recurrent DVT and PE

Available as 15mg, 30mg and 60mg tablets

34
Q

What are the contra-indications of endoxaban?

A

Clinically significant active bleeding, hepatic disease associated with coagulopathy and clinically relevant bleeding risk.
Significant risk of major bleeding,
Uncontrolled HTN, concomitant treatment with any other anticoagulants, pregnancy and breastfeeding.

Discontinue at least 24 hours before a surgical procedure.

35
Q

What monitoring is needed with endoxaban?

A

Baseline aPTT, INR, haemoglobin.

Baseline renal function and during treatment when clinically necessary, avoid in end stage renal disease or patients undergoing dialysis.

Baseline LFTs and repeat periodically if treatment lasts longer than a year.

Monitor patients for signs of bleeding or anaemia.

36
Q

What is the dose of endoxaban for the prophylaxis of stroke and systemic embolism in non-valvular AF?

A

CrCl 15-50ml/min= 30mg OD

CrCl >50ml/min= (body weight < 61kg: 30mg OD)
(Body weight > or equal to 61kg: 60mg OD)

37
Q

What is the endoxaban dose for the treatment of DVT or PE? And the prophylaxis of recurrent DVT and PE?

A

CrCl 15-50ml/min= 30mg OD (treat for at least 5 days with parental anticoagulant then switch to endoxaban)

CrCl > 50ml/min (body weight < 61kg: 30mg OD)
(Body weight 61kg and equal to 61kg: 60mg OD)

Treat for at least 5 days with parental anticoagulant then switch to endoxaban.

38
Q

What will happen to the endoxaban dose if co-prescribed with ciclosporin, dronaderone, erythromycin or ketoconazole?

A

Max dose is 30mg OD.

Dose can be increased to 60mg when the course is completed.

39
Q

What do you do if a patient has missed their endoxaban dose?

A

Take missed dose immediately after that have remembered and continue for the following day with the OD dosage.

DO NOT DOUBLE DOSE on the same day to make up for missed doses.

40
Q

What are the adverse effects of endoxaban?

A

Anaemia, hypersensitivity,
Epistaxis (nosebleed)
Nausea, rash and pruritus

41
Q

What conditions are rivaroxaban indicated for?

A

Prophylaxis of: VTE following knee and hip replacement surgery, recurrent DVT and PE, artherothrombotic events in ACS (with aspirin alone, or aspirin and clopidogrel).

Treatment of: DVT or PE.

Available as 2.5mg, 10mg, 15mg and 20mg tablets.

42
Q

What are the contra-indications of rivaroxaban?

A

Active bleeding; significant major bleeding.

In ACS- previous stroke or TIA.

43
Q

What are the monitoring requirements for rivaroxaban?

A

Baseline aPTT, INR, haemoglobin, U&E and LFTs
Baseline CrCl followed by regular monitoring of CrCl to avoid accumulation of rivaroxaban in impaired renal function.
Stop Rivaroxaban when CrCl < 15ml/min.

44
Q

What is the rivaroxaban dose for the prophylaxis of VTE post knee and hip replacement surgery?

A

CrCl 30-49, >50ml/min

KNEE= 10mg OD for 2 weeks starting 6-10 hours after surgery.

HIP= 10mg OD for 5 weeks starting 6-10 hours after surgery.

45
Q

What is the rivaroxaban dose for the treatment of DVT or PE

A

CrCl 15-29ml/min= 15mg BD for 21 days then 20mg OD. Consider reducing to 15mg if risk of bleeding outweighs risk of VTE.

CrCl 30-49, 50ml/min= 15mg BD for 21 days then 20mg OD.

46
Q

What is the rivaroxaban dose for the prophylaxis of recurrent DVT and PE?

A

CrCL 15-29ml/min = 20mg OD but consider reducing to 15mg if risk of bleeding outweighs risk of VTE.

CrCl 30-49, >50ml/min = 20mg OD.

47
Q

What is the rivaroxaban dose for the prophylaxis of stroke and systemic embolism in non-valvular AF?

A

CrCl 15-29, 30-49ml/min = 15mg OD

CrCl >50ml/min = 20mg OD

48
Q

What is the rivaroxaban dose for the prophylaxis of atherrothromotic events in ACS?

A

CrCl 30-49, >50ml/min = 2.5mg BD, continued usually for 12 months.

49
Q

Should rivaroxaban be taken with or after food or before food?

A

With food

50
Q

What advice is given if a patient missed a dose of rivaroxaban?

A

If usually taken OD: take missed dose as soon as they remember up to 12 hours before the next dose.

If less than 12 hours until their next dose: SKIP the missed dose and take the next scheduled dose as normal.

In initial phase of treatment of DVT and PE when patient is taking 15mg BD: missed dose must be taken immediately to ensure the total daily dose of 30mg has been taken.
In this case, 2 tablets can be taken at once.

51
Q

What are the adverse effects of rivaroxaban?

A

N+V, diarrhoea, constipation, dyspepsia, abdo pain, hypotension, dizziness, headache, renal impairment, pain in extremities.

52
Q

What conditions are indicated with dabigatran?

A

Prevention of stroke in non-valvular AF
Prevention of thromboembolism in total knee and hip replacement
Prevention of recurrent DVT and PE
Treatment of DVT and PE

Available as 75mg, 110mg, and 150mg CAPSULES

53
Q

What are the contra-indications of dabigatran?

A

Active bleeding; significant risk for major bleeding,

Do not use as anticoagulant for prosthetic heart valve

54
Q

What are the monitoring requirements for dabigatran?

A

Baseline aPTT, INR, haemoglobin, U&E and LFTs
Baseline renal function, including CrCl followed by regular monitoring of CrCl at least ANNUALLY.
DISCONTINUE if CrCl is <30ml/min

55
Q

What is the dabigatran dose for the prophylaxis of VTE post knee AND hip replacement surgery with the CrCl of 30-50ml/min?

A

KNEE: 75mg taken 1-4 hours after surgery, then 150mg OD
(reduce dose to 75mg OD if patient is on verapamil) for 9 days, started 12-24 hours after initial dose.

HIP: same dose and timing intervals as above, instead second dose is for 27-34 days.

56
Q

What is the dabigatran dose for the prophylaxis of VTE post knee AND hip replacement surgery with the CrCl of >50ml/min?

A

KNEE: Age 18-74 years: 110mg taken 1-4 hours after surgery, then 220mg OD
(Reduce dose to 150mg OD if patient is taking concomitant amiodarone or verapamil)
For 9 days, started 12-24 hours after initial dose.

Age > and equal to 75 years: reduce dose to 75mg, then 150mg for 9 days etc.

HIP: same dosing and timing intervals for both age groups. Instead the second dosage given is taken for 27-34 days instead.

57
Q

What is the dabigatran dose for the prophylaxis of recurrent DVT and PE and the treatment of DVT and PE with the CrCl of 30-50ml/min?

A

110mg BD, following at least 5 days treatment with a parenteral anticoagulant.

58
Q

What is the dabigatran dose for the prophylaxis of recurrent DVT and PE and the treatment of DVT and PE with the CrCl of >50ml/min?

A

18-74 years: 150mg BD, following at least 5 days treatment with a parenteral anticoagulant.

75-79 years: 110mg - 150mg BD, following at least 5 days….. as above etc.

> 80 years: 110mg BD, following ….. as above etc.
Lower dose of 110mg can also be given in moderate renal impairment, or at increased risk of bleeding, or receiving concomitant verapamil.

59
Q

What is the dabigatran dose for the prophylaxis of stroke and systemic embolism in AF?

A

CrCl of 30-50ml/min: 110mg BD

CrCl> 50ml/min:
18-74 years: 150mg BD
75-79 years: 110mg - 150mg BD
> 80 years: 110mg BD

Lower dose of 110mg can also be given in moderate renal impairment, or at increased risk of bleeding, or receiving concomitant verapamil.

60
Q

What advice is given if a patient missed their dose of dabigatran?

A

Take as soon as they remember.
If next dose is less than 6 hours away, the next dose should be missed. The missed dose should be skipped and normal dosing continued.

Patients should NOT double dose.

61
Q

What are the adverse effects of dabigatran?

A

Nausea, dyspepsia, diarrhoea, abdo pain, anaemia, haemorrhage

62
Q

What are the risk factors for DOACS to be an option for the prevention of stroke and systemic embolism in non valvular AF?

A

Patient would have one or more of the risk factors:

  • previous stroke or TIA
  • congestive HF
  • age 75 and over
  • diabetes
  • HTN