1) Antithrombotic agent 
An antithrombotic agent is a drug that reduces the formation of blood clots (thrombi). Antirhombotics can be used therapeutically for prevention (primary prevention, secondary prevention) or treatment of a dangerous blood clot (acute thrombus). In the U.S., the American College of Chest Physicians publish clinical guidelines for clinicians for the...
preventing or interfering with the formation of thrombi; an agent that so acts.
<pharmacology> An agent that prevents or interfers with the formation of thrombi. ... (13 Jan 1998) ... 
(an″te-) (an″ti-throm-bot´ik) preventing or interfering with the formation of thrombi. an agent that has this effect, such as heparin or coumarin. See also anticoagulant and thrombolytic.