HEPARIN

What it is

Heparin sodium is a preparation containing the sodium salt of a sulfated glucosaminoglycan present in mammalian tissues. It is prepared from the lungs or from the intestinal mucosae of pigs. Heparin Injection is a solution for injection, presented as a clear, colourless to straw coloured, sterile, preservative-free solution. Heparin Injection is available in strengths of 5,000 IU/5 mL or 25,000 IU/5 mL.

Approved indications

— Prophylaxis and treatment of thromboembolic disorders such as thrombophlebitis, pulmonary embolism, coronary or venous thrombosis and occlusive vascular disease. — Prevention of thromboembolic complications arising as a result of cardiac and arterial surgery, as a low-dose regimen. — As an anticoagulant during blood transfusions, extracorporeal circulation, dialysis and other perfusion techniques and in blood samples for laboratory purposes.

Dosing overview

There is a wide variation between individuals in the dose required to control thromboembolism and heparin dose is usually determined empirically by adjustment according to the results of laboratory tests. Heparin may be given by intermittent intravenous injection, intravenous infusion or deep subcutaneous injection. It should not be given intramuscularly due to the risk of haematoma formation at the injection site. For low-dose prophylaxis of postoperative thromboembolism, the usual dose is 5,000 IU by deep subcutaneous injection, repeated every 8–12 hours for seven days following surgery or until the patient is ambulatory, whichever is longer. For continuous intravenous infusion in established venous thrombosis or pulmonary embolism, a bolus dose of 5,000 IU may be given initially followed by an infusion of 20,000–40,000 IU in one litre of 0.9% Sodium Chloride Injection or in any other compatible solution over 24 hours. For intermittent intravenous injection, an initial dose of 10,000 IU either undiluted or in 50–100 mL 0.9% Sodium Chloride Injection is followed by 5,000–10,000 IU every four to six hours.

Key safety warnings

Haemorrhage can occur at virtually any site in patients receiving heparin. An unexplained fall in haematocrit, a fall in blood pressure, or any other unexplained symptom should lead to serious consideration of a haemorrhagic event. Heparin should be used with extreme caution in conditions in which there is an increased risk of haemorrhage, including gastric or duodenal ulcers; subacute bacterial endocarditis; severe hypertension; surgery especially involving the brain, eye or spinal cord; and haematological conditions associated with increased bleeding tendencies. When neuraxial anaesthesia (epidural/spinal anaesthesia) or spinal puncture is employed, patients anticoagulated or scheduled to be anticoagulated with unfractionated heparin are at risk of developing an epidural or spinal haematoma which can result in long-term or permanent paralysis. The risk is increased by the use of indwelling epidural or spinal catheters and by the concomitant use of drugs affecting haemostasis. The risk also appears to be increased by traumatic or repeated epidural or spinal puncture. Heparin-induced Thrombocytopenia (HIT) is a serious antibody-mediated reaction resulting from irreversible aggregation of platelets. HIT may progress to Heparin-induced Thrombocytopenia and Thrombosis (HITT). Serious thromboembolic events associated with HITT include deep vein thrombosis, pulmonary embolism, cerebral vein thrombosis, limb ischaemia, stroke, myocardial infarction, mesenteric thrombosis and gangrene of the extremities that may lead to amputation. Heparin-induced Thrombocytopenia and Heparin-induced Thrombocytopenia and Thrombosis can occur up to several weeks after the discontinuation of heparin therapy. Patients presenting with thrombocytopenia or thrombosis after discontinuation of heparin should be evaluated for HIT and HITT. Heparin can suppress adrenal secretion of aldosterone leading to hyperkalaemia, particularly in patients with raised plasma potassium or at risk of increased potassium levels such as patients with diabetes mellitus, renal insufficiency or taking drugs that may increase plasma potassium levels such as ACE inhibitors. The risk of hyperkalaemia appears to increase with the duration of treatment, but is normally reversible.

Contraindications

Heparin is contraindicated in patients with known hypersensitivity to heparin or pork products, history of heparin-induced thrombocytopenia and heparin-induced thrombocytopenia and thrombosis, severe thrombocytopenia or patients for whom suitable blood coagulation tests cannot be performed at appropriate intervals, and in patients in an uncontrollable active bleeding state except when this condition is the result of disseminated intravascular coagulation.

Regulatory history

Heparin Sodium 5000 IU/5 mL injection ampoule and Heparin Sodium 25000 IU/5 mL injection ampoule were first registered on the ARTG on 22 June 1994.