Heparin

ADMINISTRATION ROUTES:

IV

ALTERNATIVE NAMES:

Heparin, Multiparin

ICU INDICATIONS:

1. Anticoagulation

PRESENTATION AND ADMINISTRATION:

IV:

5000 units/mL in 5 mL vials (25,000 units); other formulations also available

For administration of heparin by infusion, prepare 25,000 units of heparin in 50 mLs of compatible IV fluid.

Administer via a dedicated central line or peripheral line. Discard any solution not used within 24 hours or preparation.

Compatible with the following IV fluids:

5% dextrose, Normal saline, Glucose and sodium chloride, Hartmanns

Store at room temperature

DOSAGE:

IV:

To reduce error, print an individualised ‘Heparin Infusion Calculation’ from the ICU database. This can be found under Reports/Forms -> Drug Calculations -> Heparin or Bivalirudin Infusions

Use this & the following protocol for heparin infusion in ICU only

All doses are in units/kg and should be rounded to the nearest 100 units. APTT is measured 6 hourly for patients on a heparin infusion. Unless otherwise stated, the target aPTT for patients receiving heparin by infusion is in the range of 60-80 seconds.

Note: 100 units of heparin equals 0.2 mL when prepared according to the standard dilution above.

Adapted from Raschke RA, et al: The weight-based heparin dosing nomogram compared with a standard care nomogram. Ann Intern Med 1993;119:874

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

Dose as in normal renal function

DOSAGE IN PAEDIATRICS:

IV:

75 - 200 units/kg stat followed by an infusion commencing at 15 units/kg/hr

Infusion made up as follows: 500 units/kg in 50 mL at 0-2.5 mL/hr (0-25 units/kg/hr) adjusted according to APTT

CLINICAL PHARMACOLOGY:

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.

CONTRAINDICATIONS:

1. Severe thrombocytopaenia
2. Heparin Induced Thrombotic Thrombocytopaenia Syndrome (HITTS)

WARNINGS:

Hypersensitivity:

Patients with documented hypersensitivity to heparin should be given the drug only in clearly life-threatening situations.

Haemorrhage:

Haemorrhage can occur at virtually any site in patients receiving heparin. An unexplained fall in haematocrit, fall in blood pressure, or any other unexplained symptom should lead to serious consideration of a haemorrhagic event.

Heparin sodium should be used with extreme caution in disease states in which there is increased danger of haemorrhage.

Thrombocytopaenia:

Thrombocytopaenia has been described in patients receiving heparin with a reported incidence of up to 30%. Mild thrombocytopaenia (count greater than 100,000/ mm³) may remain stable or reverse even if heparin is continued. However, reduction in platelet count of any degree should be monitored closely. If the count falls below 100,000/mm³ or if recurrent thrombosis develops, the heparin product should be discontinued.

PRECAUTIONS:

General:

Heparin Induced Thrombotic Thrombocytopaenia Syndrome (HITTS):

It has been reported that patients on heparin may develop new thrombus formation in association with thrombocytopaenia resulting from irreversible aggregation of platelets induced by heparin, also known as 'white clot syndrome'. The process may lead to severe thromboembolic complications like skin necrosis, gangrene of the extremities that may lead to amputation, myocardial infarction, pulmonary embolism, stroke, and possibly death. Therefore, heparin administration should be promptly discontinued if a patient develops new thrombosis in association with a reduction in platelet count.

Heparin Resistance:

Increased resistance to heparin is frequently encountered in fever, thrombosis, thrombophlebitis, infections with thrombosing tendencies, myocardial infarction, cancer, in post-surgical patients, and patients with antithrombin III deficiency.

Laboratory Tests:

Patients in ICU on a heparin infusion should have their aPTT measured 6 hourly.

Drug/Laboratory Test Interactions:

None noted

Pregnancy:

Animal reproduction studies have not been conducted with heparin sodium. It is also not known whether heparin sodium can cause foetal harm when administered to a pregnant woman or can affect reproduction capacity. Heparin sodium should be given to a pregnant woman only if clearly needed.

Nursing Mothers:

Heparin is not excreted in human milk.

Paediatric Use:

See DOSAGE IN PAEDIATRICS

IMPORTANT DRUG INTERACTIONS IN ICU:

Concomitant administration with warfarin, aspirin, activated protein C and enoxaparin increases the risk of bleeding.

Digitalis, tetracyclines, nicotine, or antihistamines may partially counteract the anticoagulant action of heparin sodium.

ADVERSE REACTIONS:

Body as a Whole:

Haemorrhage, anaphylactic reactions

Gastrointestinal System:

Nausea, vomiting

Respiratory System:

Angioedema, asthma-like symptoms

Haematological System:

Thrombocytopaenia, HITTS (see PRECAUTIONS)