There are several types of antiplatelet therapies, each with a specific mechanism of action:
1. Aspirin:
- Mechanism: Irreversibly inhibits cyclooxygenase-1 (COX-1), which reduces the production of thromboxane A2, a potent platelet activator.
- Effects: Inhibits platelet aggregation and adherence, slightly prolongs bleeding time.
- Uses: Prevention of myocardial infarction, stroke, peripheral arterial disease.
2. Adenosine Diphosphate (ADP) Receptor Inhibitors:
- Mechanism: Block P2Y12 receptors on platelets, preventing ADP from activating them and inducing aggregation.
- Types:
- Thienopyridines: Clopidogrel, prasugrel, ticagrelor (reversible, irreversible, reversible).
- Non-thienopyridines: Cangrelor (direct-acting, short-acting).
- Effects: Inhibits platelet aggregation and activation, moderate prolongation of bleeding time.
- Uses: Prevention of myocardial infarction, stroke, stent thrombosis, acute coronary syndromes.
3. Glycoprotein IIb/IIIa Inhibitors:
- Mechanism: Bind to GP IIb/IIIa receptors on platelets, preventing them from aggregating and forming clots.
- Types: Abciximab, eptifibatide, tirofiban (all parenteral agents).
- Effects: Strong inhibition of platelet aggregation, significant prolongation of bleeding time.
- Uses: Acute coronary syndromes, percutaneous coronary intervention (PCI), high-risk coronary artery disease.
4. Phosphodiesterase (PDE) Inhibitors:
- Mechanism: Inhibit PDE3, leading to increased cyclic AMP levels and decreased platelet activation.
- Types: Cilostazol.
- Effects: Inhibits platelet aggregation and activation, promotes vasodilation, improves blood flow.
- Uses: Peripheral arterial disease, intermittent claudication.
5. Protease-Activated Receptor (PAR) Antagonists:
- Mechanism: Block PAR-1 receptors on platelets, preventing thrombin from activating them and inducing aggregation.
- Types: Vorapaxar.
- Effects: Inhibits platelet activation and aggregation, slightly prolongs bleeding time.
- Uses: Prevention of recurrent strokes and cardiovascular events in high-risk patients.
6. Miscellaneous:
- Dipyridamole: Blocks adenosine reuptake, enhancing its antiplatelet effect.
- Nitrates: Promote vasodilation and can indirectly inhibit platelet aggregation.
It's important to note that this article compares the mechanisms and uses of these drugs generally. This article is not a medical advice. Always consult a doctor before starting any antiplatelet therapy.
