Anticoagulants, Antifibrinolytics and Anti-platelet agents

Question 1

Low molecular weight Heparin e.g Dalteparin: Mechanism of Action

Answer 1

Combine with antithrombin III and inhibit secondary haemostasis via relatively selective inactivation of factor Xa & thrombin by antithrombin, minimal effect on APTT

Question 2

Low molecular weight Heparin e.g Dalteparin: Effects

Answer 2

decrease risk of DVT and PE

Question 3

Low molecular weight Heparin e.g Dalteparin: Side Effects

Answer 3

Injection site heamatoma and pain
increased risk of bleeding

rarely hyperkalemia

Question 4

Low molecular weight Heparin e.g Dalteparin: Dose

Answer 4

5,000 Units prophylactic dose SC

Theraputic dose according to weight

Question 5

Low molecular weight Heparin e.g Dalteparin: Cautions

Answer 5

Haemorrhage, active major bleeding

Thrombocytopenia

Question 6

Warfarin: Mechanism of Action

Answer 6

Antagonises the enzyme vitamin k epoxide reductase that is required for usual vitamin k metabolism. This inhibits carboxylation of clotting factors II, VII, IX and X rendering them inactive

Question 7

Warfarin: Effects

Answer 7

More long term anticoagulation - AF, prosthetic heart valves, prophylaxis VTE
Delayed effect 48-72 hours

Question 8

Warfarin: Side effects

Answer 8

haemorrhage

Question 9

Warfarin: Cautions

Answer 9

Bleeding - should be stopped % days prior to surgery
Hemorrhagic stroke
Teratogenic

Question 10

Warfarin: Dose

Answer 10

Daily maintenance dose is 3-9mg to target INR
INR 2.5 for
Treatment VTE or PE, AF cardioversion, dilated cardiomyopathy, mitral stenosis or regurgitation

INR 3.5 for
recurrent DVT or PE

avoid cranberry juice

Question 11

DOAC (e.g. Apixiban, Riveroxiban, Dabigatrin): Mechanism of Action

Answer 11

Novel oral anticoagulants eg dabigatran (direct thrombin inhibitor) or rivaroxaban (Factor Xa inhibitor)

Question 12

DOAC: Side Effects

Answer 12

Haemorrhage

Question 13

DOAC: Cautions

Answer 13

No reversal agents available (except dabigatran)

Active bleeding

Question 14

DOAC: Dose

Answer 14

apixiban 2.5 mg BD

Question 15

Aspirin: Mechanism of Action

Answer 15

Blocks cyclooxygenase thereby blocking thromboxane A2 generation and inhibiting platelet aggregation

Question 16

Aspirin: Effects/ Clinical Use

Answer 16

platelet inhibition - Useful in unstable angina and acute MI
Management of unstable angina and non-ST-segment elevation myocardial infarction (NSTEMI),
Management of ST-segment elevation myocardial infarction (STEMI)

• cardiovascular disease secondary prevention

Question 17

Aspirin: Side Effects

Answer 17

Nausea

Question 18

Aspirin: Cautions

Answer 18

Gastrointestinal bleeding - history of ulcers

bleeding disorders

Question 19

Aspirin: Dose

Answer 19

75 mg OD

Question 20

Clopidogrel: Mechanism of Action

Answer 20

Covalently modify platelet ADP receptor, thereby preventing receptor signalling and irreversibly inhibiting ADP-dependent platelet activation

IHD: Acetylation of the platelet cyclooxygenase 1(COX 1) causing inhibition of platelet-dependent thromboxane.

Question 21

Clopidogrel: Effects/ Clinical Use

Answer 21

Secondary prevention of atherosclerotic plaque in MI or stroke

Question 22

Clopidogrel: Side Effects

Answer 22

N&V

Question 23

Clopidogrel: Cautions

Answer 23

Atrial fibrillation
Heart failure

Active bleeding
Discontinue 7 days before elective surgery if antiplatelet effect not desirable; patients at risk of increased bleeding from trauma, surgery, or other pathological conditions

Question 24

Clopidogrel: Dose

Answer 24

75mg OD, PO

Question 25

What is the mechanism of Heparin and LMWHs?

Answer 25

Inactivation of thrombin, factor Xa inhibitor

Question 26

What is the mechanism of Fondaparinux?

Answer 26

Selective factor Xa inhibitor

Question 27

What is the mechanism of Dipyridamol?

Answer 27

anti-platelet

Phosphodiesterase inhibitor

Question 28

What is the shared mechanism of Clopidogrel, Prasugrel, Ticagrelor?

Answer 28

Reversible/ irreversible P2Y12 receptor blockers