Cardiovascular Drugs Our Patients Take
Course Number: 581
Course Contents
Drugs that Affect Hemostasis
A well-regulated hemodynamic system keeps blood fluid and clot-free in normal vessels and forms a localized clot rapidly in response to vessel injury.9 The first step in the formation of a localized clot at the site of vessel injury is vasoconstriction. This is followed by platelet aggregation and the formation of a primary hemostatic plug. Secondary hemostasis, also known as the coagulation cascade, leads to the formation of a stable, durable clot. An abnormal extension of hemostasis is thrombosis.9
Thrombosis is characterized by the uncontrolled enlargement of clots that occlude blood vessels as a result of (1) injury of the endothelium associated with hyperlipidemia and hypertension; (2) abnormal blood flow, i.e. turbulence or stasis associated with atherosclerosis, arrhythmias, valvular problems, and heart failure, and (3) genetic or acquired hypercoagulability.9 Drugs in the top 300 that affect hemostasis (Table 5) fall into two major categories: antiplatelet agents and anticoagulants.2,9,10
Table 5. Drugs that Affect Hemostasis and Thrombosis.2,9,10
| Drugs (Rank/300) | Mechanisms of Action | Common Indications |
|---|---|---|
| Cyclooxygenase inhibitors • Aspirin (36) | Inhibit platelet cyclooxygenase, thereby blocking thromboxane A2-dependent platelet aggregation | • Prophylaxis against o Transient ischemic attacks o Myocardial infarction o Thromboembolic disorders o Reocclusion in coronary revascularization procedures and stent implantation |
| ADP receptor pathway inhibitors • Clopidogrel (29) • Ticagrelor (247) | Block platelet ADP receptors thereby inhibiting ADP-dependent platelet activation • Clopidogrel irreversibly blocks ADP receptors • Ticagrelor reversibly blocks ADP receptors |
• Acute coronary syndromes • Prevention of stent thrombosis in combination with aspirin • Secondary prevention of atherosclerotic events in patients with recent MI, stroke, or peripheral vascular disease |
| Traditional anticoagulants • Warfarin (58) | Inhibit hepatic peroxide reductase that catalyzes the regeneration of reduced vitamin K, which is required for the synthesis of biologically active coagulation factors II, VII, IX, and X | Prophylaxis and treatment • Pulmonary embolism • Deep vein thrombosis • Systemic embolism o Post-MI o Atrial fibrillation o Prosthetic heart valve |
| Selective Factor Xa inhibitors • Apixaban (48) • Rivaroxaban (86) | Competitively inhibit factor Xa by binding to the active side on the enzyme | • Prophylaxis against o Systemic embolism with atrial fibrillation o Deep vein thrombosis and pulmonary embolism associated with hip or knee replacement surgery • Prophylaxis and treatment o Deep vein thrombosis and pulmonary embolism |