Antiplatelets Flashcards
To create drug profiles for aspirin, clopidogrel and ticagrelor
Aspirin
Mechanism of Action
Irreversibly inhibits cyclooxygenase (COX) to prevent conversion of arachidonic acid to thromboxane (pro-aggregation factor) so that platelet aggregation and risk of arterial occlusion is reduced. Antiplatelet effect occurs at low dose (75mg) and lasts for the lifetime of the platelet.
Aspirin
Common Indications
- Reduce risk of stroke after AF when warfarin and DOACs are contraindicated.
- Secondary prevention of arterial disease
- Treatment of ACS and acute ischaemic stroke
Aspirin
Adverse effects
Gastrointestinal irritation- GI ulceration
Bronchospasm
Aspirin
Contraindications
- Avoid in under 16yo (risk of Reye’s syndrome) except in Kawasaki disease.
- NSAID hypersensitivity
- Bleeding disorders
- Caution during third trimester of pregnancy
- Avoid in breastfeeding
- Avoid in severe renal impairments
Aspirin
Law
max. 100 capsules or tablets sold OTC (no restriction on effervescent tablets.
Clopidogrel
Mechanism
Binds irreversibly to ADP receptors (P2Y12) on the surface of platelets to prevent platelet aggregation. As this process is independent of the cyclooxygenase pathway, clopidogrel can work synergistically with aspirin.
Clopidogrel
Common indications
- Treatment of ACS to reduce subsequent mortality (75mg for 1-12 months)
- To prevent occlusion of coronary artery stents
- To reduce risk of stroke after AF when warfarin and NOACs are contraindicated. (75mg for life)
Clopidogrel
Adverse reactions
GI discomfort, haemorrhage, diarrhoea
Clopidogrel
Contraindications
Active bleeding
Clopidogrel selection
If CRUSADE score is low it means the patient has a lower risk of bleeding so clopidogrel will be more appropriate than ticagrelor.
GRACE score of >1.5 Clopidogrel 300mg loading dose
Ticagrelor
Has a high bleeding risk than clopidogrel
