Using low molecular weight heparin-Enoxaparin

Contraindications (Enoxaparin (Clexane^Ò))

Hypersensitivity to enoxaparin, heparin or its derivatives

Active major bleeding

Previous heparin-induced thrombocytopenia

Precautions (Enoxaparin (Clexane^Ò)

As with any other anticoagulant therapy, LMWH should be used with caution in patients who have comorbid conditions which increase their risk of bleeding.  See Risk Factors for Haemorrhage in Anti Coagulated Patients. 

WORKING OUT THE DOSE of ENOXAPARIN

Indication	Creatinine clearance
	>80mL/min	30-80mL/min*	<30mL/min^†
DVT/PE Acute coronary syndrome Other indication for full anticoagulation	1mg/kg bd	1mg/kg bd	1mg/kg daily
DVT/PE – alternative, single-daily dosage Once a day dosing NOT suitable for treating: · acute coronary syndrome · large clot burden (eg extensive DVT) · Obese patients (maximum dose 120mg per single dose)	1.5mg/kg od	1.5mg/kg od	1mg/kg daily
DVT prophylaxis in most medical and surgical patients	40mg od	40mg od	20mg od
DVT prophylaxis in medical and surgical patients with higher bleeding risk	20mg od	20mg od	20mg od
*Although no dose adjustment is recommended in patient with a creatinine clearance of 30 – 80mL / min, careful clinical monitoring is advised. † If creatinine clearance <30mL/min, anti-Xa laboratory monitoring is indicated (see below) Dose should be rounded either up or down to the closest pre-filled syringe: 60mg/0.6ml, 80mg/0.8ml, 100mg/1ml, 120mg/0.8ml, and 150mg/1ml syringes are available. Use this table for elderly patients once the creatinine clearance is worked out. Creatinine clearance reduces with age.

Laboratory Monitoring of LMWH

In contrast to UFH, laboratory monitoring is generally not required for patients receiving LMWH.

Situations where laboratory monitoring is indicated in patients on LMWH

Renal insufficiency, creatinine clearance < 30mL/min. Even at low dose enoxaparin can accumulate in renally impaired patients

Pregnancy

Significant haemorrhage complicating LMWH therapy

Extremes of body weight

· Discuss with a haematologist If you are considering anti-Xa tests to monitor LMWH therapy. They will advise about adjusting the dose of LMWH according to anti-Xa levels.

· The timing of anti Xa tests is critical. Usually, the anti-Xa levels are measured both pre dose and 4 hours post dose.

Therapeutic range

Anti-Xa therapeutic levels vary between brands of LMWH, eg enoxaparin (Clexane) Vs dalteparin (fragmin). Specify on the lab form which product is used for your patient.

Indication	Anti Xa level for enoxaparin
Therapeutic range (aiming for full anticoagulation)	0.3 ~ 0.7
Prophylactic range (aiming for DVT prophylaxis)	0.2 ~ 0.4

Comparing Heparin and LMWH-Pharmacodynamics

Unfractionated Heparin (UFH)	Low Molecular Weight Heparin (e.g. enoxaparin, dalteparin (Fragmin))
heterogeneous mixture of polysaccharide chains ranging in molecular weight from 3,000 to 30,000 Daltons.	a mean molecular weight of 5,000 daltons
Predominantly anti-thrombin activity	increased anti-Xa activity and less activity against thrombin. Peak anti-Xa activity 3 to 5 hours after sc injection.
Erratic bioavailability sub cutaneously	better bio-availability subcutaneously
Half life short and variable (2 - 4 hrs sub cut, 15-30 minutes IV)	The plasma half life of LMWH more predictable after sub cut injection; half-life 3-6 hours, 7 hours after repeat injections

For more information go to www.medsafe.govt.nz for data sheets

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