Charles V. Pollack, MD is a clinician scientist and senior physician who has spent nearly four decades advancing patient care and drug development in thrombosis and hemostasis. As head of CGP Consulting, PC, he collaborates with pharmaceutical and biotech teams on protocol design, trial oversight, and medical authorship.
He also serves as a clinician scientist at the University of Mississippi Medical Center, where he has been on the faculty since 2019 and twice led the University of Mississippi Medical Research Foundation. With more than 500 publications, Charles V Pollack MD has helped clarify the benefits and risks of antithrombotic therapy and strategies for reversal. His background includes leadership roles across academic and hospital settings and recognition from the American College of Emergency Physicians. The following article summarizes core concepts in antithrombotic therapies for prevention and treatment of thrombosis.
Antithrombotic Therapies
Thrombosis is the cpathologic clotting of blood in a blood vessel, blocking blood flow and resulting in life-threatening health conditions such as stroke and heart attack, among others. This is separate and distinct from hemostasis, , which is a normal and restorative physiological response to injury. Antithrombotic therapy helps prevent and treat thrombosis. Since thrombosis and hemostasis are closely related, the challenge is producing antithrombotic therapies that do not expose patients to excessive blood loss.
Anticoagulants slow down the clotting process. They keep fibrin, the blood protein responsible for healing wounds, and platelets, white blood cells, and red blood cells from coming together to form a clot. Examples of anticoagulants are heparin, apixaban (Xarelto), and rivaroxaban (Xarelto).
Antiplatelet agents help prevent blood clotting in arteries by impairing platelets. Platelets are cells that move to a site of injury and band together into a clot, thus preventing excessive bleeding. Antiplatelets prevent them from merging. Examples of antiplatelets are aspirin, ticagrelor (Brilinta), and clopidogrel (Plavix).
Anticoagulants and antiplatelets are blood thinners. They only prevent blood clots and help prevent existing clots from getting bigger. They don’t break up existing clots. This is where thrombolytics come in.
Also called fibrinolytics, thrombolytics break up existing clots by activating a protein that dissolves the fibrin in a clot. Their use is reserved for when a clot is life threatening, unlike blood thinners, which can be taken every day. Alteplase, (Aactivase),, and tenecteplase (TNKase) are examples of thrombolytics. Thrombolytics treat ischemic stroke, heart attack, DVT (deep vein thrombosis), and arterial thrombosis.
Adverse effects of thrombolytics may include severe bleeding if clots elsewhere in the body are affected.
The major challenge facing antithrombotic therapies has been preventing blood clots in the wrong places while preserving normal hemostasis, thus limiting the risk of excessive bleeding due to thinned blood. Hemostasis is the process of stopping excessive bleeding and repairing damage. Studies are focusing on identifying safer targets, making existing targets safer, and reversal measures.
The most promising new targets in the blood clotting process are inhibitors of coagulation Factor XI and XIa. These are largely non-essential for hemostasis but contribute importantly to thrombosis.
On the reversal front, protamine has proved effective for reversing heparins and 4-factor PCC for reversing warfarin. Andexanet alfa can specifically reverse the anticoagulant effects of apixaban and rivaroxaban. A monoclonal antibody, idarucizumab (the Phase 3 trial of which was led by Dr Pollack), acts as a specific reversal agent for. dabigatran action within minutes.
Given the potential adverse effects of antithrombotic therapy, behavioral modifications are key to reducing the risk of developing thrombosis. They include maintaining an active lifestyle, avoiding smoking, and managing other health conditions like heart failure and COPD.
Despite improvement in antithrombotic therapy, the risk of excessive bleeding continues to hamper appropriate use. It is hoped that the development of anticoagulants that specifically target FXI or FXIa may address these safety concerns while still providing adequate anticoagulation.
About Charles V Pollack MD
Charles V. Pollack, MD is a veteran emergency physician and drug developer with extensive expertise in thrombosis and antithrombotic therapy. He leads CGP Consulting, PC, partnering with life science companies on clinical development, monitoring, and authorship. At the University of Mississippi Medical Center, he holds an appointment as a clinician scientist and has served as president of the University of Mississippi Medical Research Foundation. Charles V Pollack MD has authored more than 500 publications and serves on editorial boards and as a peer reviewer.
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