What are they
Antiplatelet drugs are all drugs that interfere with the functioning of platelets (corpuscles present in the blood that intervene in the phenomena of hemostasis, or in the arrest of a hemorrhage) obtaining, as a final result, the blocking of their aggregation.
The aggregation of platelets, which represents the first event of hemostasis is actually only the latest in a series of reactions that together constitute the process of “platelet activation”.
Since many of these drugs do not intervene directly on the actual aggregation of platelets, but in the previous stages of their activation, they are more correctly called “antiplatelets”.
Hemostasis itself is a protective phenomenon, which serves to stop blood loss in the event of injury to a blood vessel.
However, it can also be triggered improperly – in the absence of bleeding – in some pathological conditions (blood hypercoagulability, thrombocytosis, slowing of circulation, atherosclerosis) and cause the formation of thrombi (which are agglomerates of platelets and coagulated blood).
For this reason, antiplatelet drugs are part, together with anticoagulants and fibrinolytics, of the broader category of “antithrombotics”.
What are they?
The most well-known molecule of greater clinical importance in the category of antiplatelets is acetylsalicylic acid, which blocks the activation of platelets in one of its early stages.
The other antiplatelets that have clinical application are: sulfinpyrazone, dipyridamole, indobufene, ticlopidine, clopidogrel, abciximab, tirofiban, eptifibatide, epoprostenol.
Antiplatelets can be classified according to their mechanism of action:
| Mechanism of action | Active ingredients |
|---|---|
| Modulation of arachidonic acid (AA) metabolism | Acetylsalicylic acid, indobufene, triflusal, picotamide |
| Inhibition of adenosine diphosphate (ADP) platelet receptor P2Y12 | Ticlopidine, clopidogrel, prasugrel, ticagrelor, cangrelor, elinogrel |
| Increased levels of cyclic adenosine monophosphate (cAMP) | Dipyridamole, cilostazol |
| Inhibition of platelet glycoprotein GpIIb/IIIa | Abciximab, eptifibatide, tirofiban |
| Inhibition of the Proteinase activated Receptor (PAR)-1 |
Vorapaxar |
When using
The main application of antiplatelets is the prevention of arterial thrombosis, both in people at risk and in those who have had previous thrombotic episodes.
These drugs are then prescribed in case of:
- previous myocardial infarction;
- high risk of myocardial infarction (coronary syndrome, peripheral arterial diseases on an atherosclerotic basis);
- atrial fibrillation (when anticoagulants are contraindicated);
- after coronary surgery (by-pass, stenting, angioplasty);
- previous transient cerebral ischemic attack or thrombotic cerebral stroke.
How to use them
The most widely used drug for prolonged oral therapy is acetylsalicylic acid at doses lower than those necessary for the inflammatory effect.
Dipyridamole and clopidogrel are also commonly used, alone (for example in patients intolerant to acetylsalicylic acid) or in combination treatment with acetylsalicylic acid to achieve a greater protective effect in patients at high risk of arterial thrombosis.
Some of the drugs mentioned above are instead reserved for specific clinical applications, for hospital use and intravenous administration: abciximab during coronary surgery; tirofiban and eptifibatide in the acute phase of coronary syndrome (unstable angina and heart attack); epoprostenol during hemodialysis and hemofiltration procedures or in case of severe pulmonary hypertension.
Joycelyn Elders is the author and creator of EmpowerEssence, a health and wellness blog. Elders is a respected public health advocate and pediatrician dedicated to promoting general health and well-being.
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