Нeparin (or Unfractionated heparin ) is an anticoagulant indicated for both the prevention and treatment of thrombotic events such as deep vein thrombosis (DVT) and pulmonary embolism (PE) as well as atrial fibrillation (AF). Heparin can also be used to prevent excess coagulation during procedures such as cardiac surgery, extracorporeal circulation or dialysis, including continuous renal replacement therapy. Heparin administration can be by intravenous (or subcutaneous route. Intravenous heparin is continuously administered for therapeutic anticoagulation, while intermittent subcutaneous administration is used to prevent thromboembolism. Once administered, heparin binds reversibly to antithrombin III (ATIII) and greatly accelerates the rate at which ATIII inactivates coagulation enzymes thrombin (factor IIa) and factor Xa. The heparin-ATIII complex can also inactivate factors IX, XI, XII, and plasmin, but the antithrombotic effect of heparin is well correlated to the inhibition of factor Xa. Typical adverse effects from heparin use include bleeding, thrombocytopenia, injection site reactions, and other adverse effects only seen with chronic heparin administration. Bleeding is a major complication associated with heparin use. Patients should undergo monitoring for new bleeding that may present in the urine or stool. Bleeding may also present as bruising, petechial rash and nosebleeds.