INTRAVENOUS Unstable angina; Venous.
Heparin inhibits reactions that lead to the clotting of blood and the formation of fibrin clots both in vitro and in vivo. Heparin acts at multiple sites in the normal coagulation system. Small amounts of heparin in combination with antithrombin III (heparin cofactor) can inhibit thrombosis by inactivating activated Factor X and inhibiting the conversion of prothrombin to thrombin. Once active thrombosis has developed, larger amounts of heparin can inhibit further coagulation by inactivating thrombin and preventing the conversion of fibrinogen to fibrin. Heparin also prevents the formation of a stable fibrin clot in inhibiting the activation of the fibrin stabilizing factor.
Bleeding time is usually unaffected by heparin. Clotting time is prolonged by full therapeutic doses of heparin; in most cases, it is not measurably affected by low doses of heparin.
thromboembolism; Peripheral arterial embolism: Adult: 5000 u (10,000 u/ in severe pulmonary embolism) IV loading dose followed by 1000-2000 u/ hr continuous infusion. Alternatively, intermittent inj of 5000-10,000 u every 4-6 hr. Child: Administer a lower loading dose. Maintenance: 15-25 u/kg/hr continuous infusion. Prophylaxis of re-occlusion of the coronary arteries following thrombolytic therapy in myocardial infarction: Adult: 5000 u IV followed by 1000 u/hr IV w/ alteplase. SUBCUTANEOUS Venous thromboembolism: Adult: 15,000 u injected every 12 hr. Child: 250 u/kg every 12 hr. Prophylaxis of postoperative venous thromboembolism: Adult: 5000 u given 2 hr before surgery then every 8-12 hr for 7 days or until the patient is ambulant, may increase to 10,000 u every 12 hr during the 3rdtrimester of pregnancy. Prophylaxis of mural thrombosis:Adult: 12,500 u every 12 hr for at least 10 days.
Enhanced anticoagulant effect with other drugs affecting platelet function or the coagulation system (e.g. platelet aggregation inhibitors, thrombolytic agents, salicylates, NSAIDs, vit K antagonists, dextrans, activated protein C). Decreased anticoagulant effect with gyceryl trinitrate infusion. Increased risk of hyperkalaemia with ACE inhibitors or angiotensin II antagonists.
Patients predisposed to active bleeding including thrombocytopenia, peptic ulcer disease, cerebrovascular disorders, haemorrhagic blood disorders, bacterial endocarditis, severe hypertension, oesophageal varices. Recent surgery at sites where haemorrhage would be an especial risk. Severe renal & hepatic impairment. Cerebral or subarachnoid haemorrhage, abdominal or thoracic bleeding into closed space, severe traumatic bleed, hepatic, renal, splenic or arterial injury, severe haemostatic defect, arterial thrombosis w/ heparin-associated thrombocytopenia. IM admin. Monitor platelet counts. Discontinue treatment if thrombocytopenia occurs. Hypersensitivity, elderly, pregnancy.
Slight fever, headache, chills, nausea, vomiting, constipation, epistaxis, bruising, slight haematuria, skin necrosis (SC inj), osteoporosis, alopecia. Hypersensitivity reactions include urticaria, conjunctivitis, rhinitis, asthma, angioedema & anaphylactic shock. Priapism. Heparin-induced thrombocytopenia w/ or w/o thrombosis; bleeding.
Heparin does not cross the placental barrier. Studies have been completed on Heparin use during pregnancy. Early studies suggested Heparin, compared with other anticoagulants, offered no clear benefits over other drugs. However, later studies proved when other medical conditions were taken into consideration, Heparin was more effective. There were no increased risks of pregnancy complications or birth defects associated with Heparin use during pregnancy. Heparin does not pass to baby in milk, so there are no possible side effects associated with breastfeeding while taking Heparin. However, it is important to talk with your doctor about the fact that you’re breastfeeding before starting treatment.
Symptoms: Bleeding (nose bleeds, blood in urine or tarry stools may be noted as the 1st sign of bleeding).
Management: May give protamine sulfate by slow IV infusion over 10 min to treat severe bleeding (1 mg of protamine sulfate neutralises approx 100 U of heparin). Max: 50 mg as a single dose.
Store between 20-25° C. Protect from freezing.
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