Fondared 2.5 mg Injection 0.5 ml belongs to a class of drugs known as anticoagulants or blood thinners. Fondared 2.5 mg Injection 0.5 ml contains ‘Fondaparinux sodium’ used to prevent deep vein thrombosis (blood clot in the blood vessels of legs) and pulmonary embolism (blood clot in the blood vessels lungs). It also reduces the risk of blood clots during orthopedic (such as hip or knee surgery), abdominal surgery, or restricted movement because of an acute illness. Fondared 2.5 mg Injection 0.5 ml works by stopping the action of clotting factor Xa (a natural substance in the blood that causes clotting). This inhibits fibrin production (a protein that binds platelets together and forms a clot), preventing blood clot formation. Fondared 2.5 mg Injection 0.5 ml is also used to treat certain types of heart attack and chest pain called unstable angina.