Enoxaparin

Enoxaparin

[40mg pre-mixed syringe $6.22]

ADMINISTRATION ROUTES:

  • SC

ALTERNATIVE NAMES:

  • Clexane

ICU INDICATIONS:

  1. therapeutic anticoagulation
  2. DVT prophylaxis

PRESENTATION AND ADMINISTRATION:

  • SC:
    Pre-mixed syringes 20mg/0.2ml, 40mg/0.4ml, 100mg/ml
    Do not remove air bubble from pre-mixed syringe prior to injection Inject at 90 degrees to the skin on the lower abdomen. Alternate between the left and right anterolateral abdominal wall
    Do not rub injection site after injection

DOSAGE:

  • SC:
    DVT prophylaxis:

    40mg sc daily (ALWAYS chart this at night. As most procedures happen during daylight hours, prescribing enoxaparin at night reduces the risk of procedural bleeding secondary to enoxaparin)
    Therapeutic enoxaparin:

    The standard treatment doses of enoxaparin (weight adjusted) are either 1mg/kg twice daily or 1.5mg/kg once daily
    Enoxaparin dosing in extremes of bodyweight:
    The dose of enoxaparin does not need to be adjusted in the morbidly obese (BMI >35, or greater than 150kg), or those with a BMI <20 (underweight). These patients should be dosed on a mg/kg basis in the same way as patients of normal bodyweight, with adjustment for renal impairment if needed. There is evidence that twice daily dosing is safer for patients with BMI >35 or weight >150kg.
    People at extremes of bodyweight (BMI <20 or >35) should have their Anti Xa level checked after 48 hours of dosing of enoxaparin, and the dose of enoxaparin adjusted as above.

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

  • Dose in renal impairment [GFR (ml/min)]
    <30: 0.66mg/kg 12 hourly
    30-59: 0.8mg/kg 12 hourly

    Note: the above doses are for therapeutic clexane; the recommended dose for DVT prophylaxis in patients with a GFR of <30 is 20mg daily

  • Dose in renal replacement therapy
    Use systemic heparinisation in ICU in these patients

DOSAGE IN PAEDIATRICS:

  • Therapeutic Enoxaparin:
    1mg/kg 12 hourly sc
  • Prophylactic Enoxaparin:
    <2 months: 0.75mg/kg 12 hourly
    2 months – 18 years: 0.5mg/kg 12 hourly

CLINICAL PHARMACOLOGY:

  • Low molecular weight heparin

CONTRAINDICATIONS

  1. hypersensitivity to enoxaparin
  2. active bleeding
  3. presence of an external ventricular drain

WARNINGS

  • Bleeding Risk:
    Every patient being considered for enoxaparin therapy should be assessed for their risk of bleeding. This assessment should be documented in the patient’s notes. There is an increased risk of any bleeding with enoxaparin use in patients who: are elderly (>65yo), have a BMI <20, have renal impairment, require a prolonged period of treatment, take concomitant clopidogrel (an 8-fold increased risk of major bleeding), aspirin or NSAID (3-4 fold increased risk), have had a previous upper GI bleed, have moderate hypertension (BP 140-180 systolic, 90-110 diastolic, even if on treatment), have multiple medical co- morbidities (especially diabetes, previous CVA or heart failure), have undiagnosed iron deficiency anaemia (in non-menstruating woman).

PRECAUTIONS

  • General:
    Many ICU procedures require reversal of anticoagulation. As enoxaparin is a not readily reversed, therapeutic systemic heparinisation may be a more appropriate choice in the many ICU patients
  • Laboratory Tests:
    Routine Anti Xa monitoring is not recommended.

    Patients requiring Anti Xa monitoring

    Measuring peak Anti Xa activity is recommended for patients on therapeutic doses of clexane in the following situations:
    - patients with moderate renal impairment (CrCl <60ml/min) patients who weigh <50kg patients who are morbidly obese (BMI >35) pregnant patients
    - patients receiving treatment dose enoxaparin for longer than 14 days patients with changing renal function have increased risk of bleeding (see above)

    When to monitor Anti Xa
    Peak Anti-Xa concentration yields the best correlation with clinical effect, and risk of bleeding.
    Anti Xa monitoring should only occur when enoxaparin is at steady state, which occurs after about 48 hours (5 half lives). It is not recommended that Xa levels are taken prior to this, as they are unable to be interpreted. Patients receiving enoxaparin for less than 48 hours do not need Anti Xa monitoring.
    Peak Anti Xa should be taken 4 hours after the dose of enoxaparin is given.

    Trough measurements
    Measuring trough Anti Xa activity routinely is not recommended as the correlation between bleeding risk and trough Anti Xa has not been clearly established. Trough Anti Xa concentrations should however be monitored at the end of the dosing interval for patients with severe renal impairment (GFR <30ml/min) if the decision to use enoxaparin has been made. These patients should also have peak Anti-Xa levels taken. For twice daily dosing, the sample should be taken 12 hours after a dose, immediately preceding the next dose, and should be ≤ 0.5IU/ ml. If the trough level is > 0.5 IU/ml, the patient should be changed to once daily dosing of enoxaparin, using the above nomogram. For once daily dosing, the sample should be taken 20 hours after a dose, and should be ≤ 0.4 IU/ml.

    Therapeutic range
    The therapeutic peak Anti Xa range for treatment dose enoxaparin is 0.5−1.2 IU/ ml for twice daily dosing, or 1−2 IU/ml for once daily dosing. The dose should be adjusted using the following nomogram.

NB: These nomograms are only valid if the patient is not bleeding and the renal function is stable.

  • Drug/Laboratory Test Interactions
    None noted.

IMPORTANT DRUG INTERACTIONS FOR THE ICU

  • Increased risk of bleeding when combined with other anti-platelet and anticoagulant agents

ADVERSE REACTIONS

  • Body as a Whole:
    Bleeding, anaphylaxis, fever
  • Cardiovascular System:
    Peripheral oedema
  • Haematological System:
    Anaemia, thrombocytopaenia, HITTS
  • Gastrointestinal System:
    GI upset, elevated LFTs
  • Local:
    haematoma (at injection site), skin necrosis

Critical Care Drug Manual

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