Anticoagulants

Question 1

What are the two main indications for anticoagulants?

Answer 1

Treatment - vte (DVT/PE)

Prophylaxis - vte (DVT/PE/stroke)

Question 2

Describe how low molecular weight heparin works?

Answer 2

Factor Xa inhibitor

Question 3

How often is LMWH given and by what route?

Answer 3

OD/BD

SC

Question 4

Is monitoring required for LMWH?

Answer 4

no

Only in special situations check activated factor X levels

Question 5

What should you do to the dose of LMWH in renal failure?

Answer 5

Reduce if for prophylaxis

Question 6

How is unfractionated heparin given?

Answer 6

IV/SC

Question 7

Describe how unfractionated heparin works?

Answer 7

Binds to antithrombin III (endogenous inhibitor of coagulation). Increases its ability to inhibit thrombin, factor Xa and IXa

Question 8

Describe the speed of onset of unfractionated heparin

Answer 8

Fast onset

Question 9

How is unfractionated heparin monitored and dosed?

Answer 9

APTT

Question 10

List the side effects of both LMWH and UFH

Answer 10

Increased bleeding
Heparin induced thrombocytopenia (HIT)
Osteoporosis with long term use (less common in LMWH than UFH)
Hyperkalaemia

Question 11

Which side effects are less common in LMWH than UFH

Answer 11

HIT and osteoporosis

Question 12

What are the contraindications to heparins

Answer 12

Bleeding disorders
Platelets <60X10^9 
Previous HIT 
Peptic ulcer 
Cerebral haemorrhage 
Neurosurgery 
Severe hypertension

Question 13

Name some low molecular weight heparins

Answer 13

Dalteparin
Enoxaparin
Tinzaparin

Question 14

Describe the mechanism of action of warfarin

Answer 14

Inhibits the reductase enzyme and stops vitamin K being activated - creates a similar state to vit K deficiency

Question 15

Describe the therapeutic range of warfarin

Answer 15

Narrow

Question 16

List the CI of warfarin

Answer 16

Peptic ulcer, severe HTN, pregnancy, bleeding disorders

Question 17

How is warfarin taken?

Answer 17

PO OD

Question 18

What is warfarin used for?

Answer 18

Long term anticoagulation

Question 19

When should warfarin be used with caution?

Answer 19

Elderly and those with past GI bleeds

Question 20

Give the doses and colours of warfarin tablets

Answer 20

White = 0.5mg
Brown = 1mg
Blue = 3mg
Pink = 5mg

Question 21

Name some drugs which increase activity of warfarin

Answer 21

Alcohol
Allopurinol
Amiodarone
Levothyroxine 
Phenytoin 
Aspirin 
Chloramphenicol 
Simvastatin 
Ciprofloxacin
Erythromycin

Question 22

Name some drugs which decrease the activity of warfarin

Answer 22

Barbiturates
Vitamin K 
Carbamazepine 
Rifampicin 
Steroids

Question 23

Name some direct oral anticoagulants

Answer 23

Rivaroxaban
Apixaban
Dabigatran

Question 24

Give the mechanism of action for dabigatran

Answer 24

Direct thrombin inhibitor (II)

Question 25

Give the mechanism of action for rivaroxaban and apixaban

Answer 25

Factor Xa inhibitors

Question 26

Do DOACs require any monitoring?

Answer 26

No - just quarterly assessment and annual blood test

Question 27

List the CI to DOACs

Answer 27

Active bleeding Lesion at risk of bleeding Decreased clotting factors

Question 28

Which two drugs interact with DOACs

Answer 28

Heparin | Clopidogrel

Question 29

Give the mechanism of action of fondaparinux

Answer 29

Penta saccharide Xa inhibitor

Question 30

When may fondaparinux be used?

Answer 30

ACS or in place of LMWH for prophylaxis

Question 31

Describe how you switch between LMW/UFH to warfarin

Answer 31

Give heparin in combination and continue until INR is in therapeutic range for 2 consecutive days Start warfarin 5-10mg on days 1 and 2 at 18.00, then check INR on day 3 (takes 48-72hrs to work) Adjust dose according to INR Measure INR in alternate days till stable, then weekly, then less often

Question 32

Describe how you transition from heparin to a DOAC

Answer 32

Do not administer heparin with a DOAC | Just switch

Question 33

Describe how you manage a UFH overdose?

Answer 33

Stop infusion

Question 34

What should you give someone with an UFH overdose who is bleeding

Answer 34

Protamine sulphate

Question 35

Name two things which can be used to reverse warfarin

Answer 35

``` Vitamin K (but takes ages to work) Prothrombin complex concentrate ```

Question 36

What is contained in a prothrombin complex concentrate

Answer 36

Factors 2,7,9,10

Question 37

Give the targeted INRs

Answer 37

2-3 if DVT/PE 3.5 if recurrent or while anticoagulated 2-3 if AF 2-3.5 if prosthetic metal valve

Question 38

How long should someone be anticoagulated for after 1st episode of VTE

Answer 38

3 months or 6 months if life threatening clot at presentation and those with transient but persistent RF

Question 39

How long should a person be anticoagulated for if recurrent unprovoked emboli or underlying thrombophilia?

Answer 39

Indefinite treatment but consider bleeding risk

Question 40

How long before surgery should warfarin be stopped?

Answer 40

5 days

Question 41

How does warfarin affect PT and APTT?

Answer 41

Increased PT | Normal APTT

Question 42

At what INR should warfarin be restarted after being stopped due to bleeding?

Answer 42

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