Pharmacology Heparin is the most widely used antithrombotic agent. It act by activating: (PGI June 2009) A Plasmin B Antithrombin III C Fibrinolysin D Factor X 💡 Explanation Heparin is the most widely used antithrombotic agent. It act by activating: (PGI June 2009) ✓ Correct Answer: B. Antithrombin III