Antiplatelet drugs

Question 1

In the arterial circulation, thrombi are composed mainly of (?)

Answer 1

platelets with little fibrin

Question 2

Is aspirin used in primary prevention of cardiovascular disease, in patients with or without diabetes, or hypertension?

Answer 2

NO

Long-term use of low-dose aspirin is recommended in patients with established cardiovascular disease (secondary prevention)

Question 3

What needs to be controlled prior to prescribing long-term low-dose aspirin for secondary prevention of cardiovascular disease?

Answer 3

Blood pressure

Question 4

What should be used in addition to aspirin if a patient is at high risk of gastrointestinal bleeding?

Answer 4

Proton pump inhibitor

Question 5

Name 6 cardiovascular indications for the use of aspirin

Answer 5

1. Following coronary bypass surgery
2. Atrial fibrillation
3. Intermittent claudication
4. Stable angina
5. Acute coronary syndrome
6. Ischaemic stroke/TIA

Question 6

What is the dose of low-dose aspirin?

Answer 6

75 mg daily

Question 7

Which antiplatelet drug can be used as monotherapy for prevention of atherothrombotic events instead of in combination with aspirin when aspirin is contraindicated?

Answer 7

Clopidogrel

Question 8

Which antiplatelet can be used in prevention of atherothrombotic and thromboembolic events in patients with atrial fibrillation and at least one risk factor for a vascular event (in combination with aspirin) when warfarin is unsuitable?

Answer 8

Clopidogrel

- 75 mg once daily (oral)

Question 9

Which antiplatelet is used as an adjunct to oral anticoagulation for prophylaxis of thromboembolism associated with prosthetic heart valves?

Answer 9

Dipyridamole

• Oral using immediate-release medicines: 300-600 mg daily in 3-4 divided doses
• Oral using modified release medicines: 200 mg twice daily, to be taken preferably with food

Question 10

What are the two indications of the antiplatelet drug dipyridamole?

Answer 10

1. Adjunct to oral anticoagulation for prophylaxis of thromboembolism associated with prosthetic heart valves
2. Secondary prevention of ischaemic stroke (NOT associated with AF) and TIAs (alone or with aspirin) (modified-release preparations)

Question 11

Which antiplatelet drug can be used before and during PCI in patients whom oral antiplatelets (e.g. clopidogrel, prasugrel or ticagrelor) are unsuitable?

Answer 11

Cangrelor (IV)
- Initially 30 micrograms/kg, to be given as a bolus dose, followed immediately by (by intravenous infusion) 4 micrograms/kg/minute, start treatment before percutaneous coronary intervention and continue infusion for at least 2 hours or for the duration of intervention if longer; maximum duration of infusion 4 hours.

Question 12

Following a PCI in patients with stable angina, how long should clopdogrel (in addition to aspirin) be used after a drug-eluting stent is used?

Answer 12

6 months

Question 13

Why is there an increased risk of stent thrombosis when using drug-eluting stents instead of bare-metal stents in PCI?

Answer 13

Due to slower re-endothelialisation process

Question 14

How do glycoprotein IIb/IIIa inhibitors prevent platelet aggregation?

Answer 14

Blocking the binding of fibrinogen to receptors on platelets

Question 15

Abciximab is a monoclonal antibody which binds to …

Answer 15

glycoprotein IIb/IIIa receptors (and other related sites)

Used as an adjunct to heparin (unfractionated) and aspirin for the prevention of ischaemic complications in high-risk patients undergoing percutaneous transluminal coronary intervention

Question 16

Name three glycoprotein IIb/IIa inhibitors?

Answer 16

1. Abciximab (monoclonal antibody)
2. Eptifibatide
3. Tirofiban

Question 17

What is the mode of action of eptifibatide and tirofiban?

Answer 17

glycoprotein IIb/IIIa inhibitors

Question 18

When is the antiplatelet epoprostenol used?

Answer 18

During renal dialysis when heparins are unsuitable

Question 19

When does the dose of glycoprotein IIb/IIIa inhibitors (eptifibatide, tirofiban) need to be reduced?

Answer 19

If creatinine clearance decreases

Epitifibate: Creatinine clearance < 30-50 mL/minute
Tirofiban: Creatinine clearance < 30 mL/minute

Question 20

What is the mode of administration of the antiplatelet cangrelor?

Answer 20

IV
- Initially 30 micrograms/kg, to be given as a bolus dose, followed immediately by (by intravenous infusion) 4 micrograms/kg/minute, start treatment before percutaneous coronary intervention and continue infusion for at least 2 hours or for the duration of intervention if longer; maximum duration of infusion 4 hours.

Question 21

How many days prior to elective surgery (if antiplatelet effect is not desireable) should clopidogrel be stopped?

Answer 21

7 days before elective surgery

Question 22

What do you need to monitor in patients taking ticagrelor?

Answer 22

Renal function 1 month after initiation in patients with acute coronary syndrome