Heparin

Heparin

[25000IU in 5ml $2.73]

ADMINISTRATION ROUTES:

  • IV

ALTERNATIVE NAMES:

  • Heparin, Multiparin

ICU INDICATIONS:

  1. anticoagulation

PRESENTATION AND ADMINISTRATION:

  • IV:
    5000 units/ml in 5ml vials (25000 units); other formulations also available
    For administration of heparin by infusion, prepare 25000 units of heparin in 50mls 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:
    Use the following protocol for heparin infusion in the ICU ONLY (print an individualised heparin infusion protocol from the database).
    All doses are in units/kg and should be rounded to the nearest 100 units (note: 100 units equals 0.2ml when heparin is prepared according to the standard dilution above).
    APTT should be measured 6 hourly.

Adapted from Raschke RA, Reilly BM, Guidry JR, 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 infusion commencing at 15 units/kg/hr
    Infusion made up as follows:
    500 units / kg in 50ml 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 thrombocytopenia

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 hematocrit, fall in blood pressure, or any other unexplained symptom should lead to serious consideration of a hemorrhagic event.
    Heparin sodium should be used with extreme caution in disease states in which there is increased danger of haemorrhage
  • Thrombocytopenia
    Thrombocytopenia has been reported to occur in patients receiving heparin with a reported incidence of 0% to 30%. Mild thrombocytopenia (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 thrombocytopaenia thrombosis syndrome (HITTS)

    It has been reported that patients on heparin may develop new thrombus formation in association with thrombocytopenia resulting from irreversible aggregation of platelets induced by heparin, the so-called “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 postsurgical 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 FOR THE 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)

Critical Care Drug Manual

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