ANTITHROMBOTIC – INTRODUCTION
Antithrombotic drugs, which include antiplatelet and anticoagulant therapies, prevent and treat many cardiovascular disorders and, as such, are some of the most commonly prescribed drugs worldwide.
ANTITHROMBOTIC – INDICATION
An antithrombotic agent is a drug that reduces the formation of blood clots (thrombi). Antithrombotics can be used therapeutically for prevention (primary prevention, secondary prevention) or treatment of a dangerous blood clot (acute thrombus).
ANTITHROMBOTIC – INFORMATION
The mechanisms by which the body controls blood fluidity are very complex, as blood must flow freely yet be able to clot quickly when endothelium is injured. A critical homeostatic balance exists between procoagulant and anticoagulant reactions, preventing both hemorrhage and thrombosis during normal daily activities. The medications discussed in this article have very different mechanisms of action, but all were designed with one primary goal: to alter the balance between procoagulant and anticoagulant properties of blood. The benefits, as well as the toxicities of these medications, are related to their mechanisms of action. For instance, an anticoagulant given to increase clotting time can cause bleeding when taken in excessive doses. This article focuses on the major steps involved in blood coagulation and will identify specific pathway alterations caused by various medications given to maintain blood fluidity. The Table provides a summary of the various antithrombotic drug classes, representative agents, mechanisms of action, and approved indications.
Antithrombotic drugs, which include antiplatelet and anticoagulant therapies, prevent and treat many cardiovascular disorders and, as such, are some of the most commonly prescribed drugs worldwide. The first drugs designed to inhibit platelets or coagulation factors, such as the antiplatelet clopidogrel and the anticoagulant warfarin, significantly reduced the risk of thrombotic events at the cost of increased bleeding in patients. However, both clopidogrel and warfarin have some pharmacological limitations including interpatient variability in antithrombotic effects in part due to the metabolism, interactions (eg, drug, environment, and genetic), or targets of the drugs. Increased knowledge of the pharmacology of antithrombotic drugs and the mechanisms underlying thrombosis has led to the development of newer drugs with faster onset of action, fewer interactions, and less interpatient variability in their antithrombotic effects than previous antithrombotic drugs. Treatment options now include the next-generation antiplatelet drugs prasugrel and ticagrelor, and, in terms of anticoagulants, inhibitors that directly target factor IIa (dabigatran) or Xa (rivaroxaban, apixaban, edoxaban) are available. In this Series paper we review the pharmacological properties of these most commonly used oral antithrombotic drugs, and explore the development of antiplatelet and anticoagulant therapies.