Flolan is mainly used in a condition referred to as pulmonary arterial hypertension (PAH). Flolan infusion contains epoprostenol sodium, which is an active ingredient. The ingredient, which is a type of medicine acts as an anticoagulant (anti-clotting agent) that dilates the blood vessels. In PAH, pulmonary arteries responsible for transporting blood from the heart to lungs become thickened and stiff. The condition increases blood pressure in these arteries making it extremely difficult for the heart to pump blood to the lungs. Flolan works by widening the pulmonary arteries hence lowering the pressure to make it easier for the heart to pump blood.