In general, all antiplatelet medications work by preventing platelets from clumping or sticking together (aggregating), which results in a prolonged bleeding time and decreased blood clot formation. The extent to which antiplatelet medications prolong bleeding time is a function of the length of time the medication is taken and the dosage.
As the smallest of all blood cells, platelets have a life span of 7 to 14 days (Ignatavicius & Workman, 2013). Most antiplatelet medications affect the ability of the platelet to aggregate for its entire lifespan, and the effects cannot be reversed.
Antiplatelet medications are generally used in preventing arterial or intracardiac thrombosis because these clots tend to be rich in platelets, whereas thrombi (and emboli) that form in the venous system tend to have a relatively low platelet content (Lehne, 2013). Antiplatelet medications are also used concurrently or in a sequence with anticoagulants and thrombolytics. Indications for antiplatelet medications include:
Management of ACS, including prophylaxis of complications after an MI or PCI with stent placement. Combination or dual antiplatelet therapy, using aspirin with a thienopyridine (ADP receptor blocker) such as clopidogrel (Plavix), is currently considered the standard of care (Preventative Cardiovascular Nurses Association, 2010).
To decrease stroke risk in patients with transient ischemic attacks (TIAs).
Patients experiencing intermittent claudication as a result of impaired peripheral arterial blood flow.
Contraindications for the use of antiplatelet medications include allergic or hypersensitivity reactions, ulcer disease, recent surgery, and active bleeding (Deglin et al., 2011). Antiplatelet medications are classified according to their specific mechanism (site) of action, overall potency, and onset of action. An overview of current antiplatelet medications is provided in Table.