Anticoagulant drugs, sometimes called anticlotting drugs or blood thinners, are prescribed to keep blood flowing at the correct rate by decreasing the amount of clotting proteins in your blood—and the right rate is a fine line. The blood must be able to clot, since this is what prevents serious blood loss if you have even the simplest cut. However, if your blood clots too quickly and easily, a clot may form inside a blood vessel, which can block blood flow to major organs and increase risk for heart attack and stroke. For this reason, a physician or trained pharmacist must carefully monitor patients taking any anticoagulant.
The most common anticoagulant in the U.S. is warfarin, with brand names such as Coumadin® and Jantoven®. Routine blood tests measure how warfarin affects a patient’s bleeding time, with the goal to achieve a dosage that keeps clotting time within a safe target range. Because diet, certain medications and alcohol consumption affect how an anticoagulant works, dosages will be adjusted from time to time.