Coumarins (such as warfarin) and Indandiones are oral anticoagulants that inhibit vitamin K-dependent clotting factors, helping to prevent and treat blood clots. These medications work by interfering with the synthesis of clotting factors II, VII, IX, and X in the liver. While Coumarins like warfarin are widely used in clinical practice, Indandiones (like phenindione) are now rarely used due to higher toxicity. Coumarins are essential in managing long-term clot prevention in conditions like atrial fibrillation, deep vein thrombosis (DVT), and mechanical heart valves.