The Hemophilia and Thrombosis Center of Nevada

2020 W. Palomino Lane Suite 110

Las Vegas, Nevada 89106

702-385-2702

since July 3, 2010

Last updated July 3, 2010

webmaster RIS

Low Molecular Weight Heparin

Low Molecular Weight Heparins are shorter chains of unfractionated heparin.  Because these are shorter compounds, they have several benefits over unfractionated heparin.  First, they may be administered via injection under the skin either once or twice daily for full effect equivalent to the intravenous administration of unfractionated heparin.  Second, because of its mechanism of action, it requires no monitoring of clotting parameters.  Because of these two important characteristics, it may administered by the patient at home without the need for hospitalization or monitoring of the clotting times.  While the medication is more expensive than unfractionated heparin, because a prolonged hospital stay is not required, overall it is much less costly than previous conventional therapy.

All heparin compounds may cause a low platelet count in some persons (See Heparin Induced Thrombocytopenia).  Low molecular weight heparins have less of an incidence of the development of this condition.  However, it may occur and should be monitored regularly by a complete blood count.  If the platelet count declines, immediate intervention may be required .

Heparin may cause osteoporosis with prolonged administration.  Low molecular weight heparin also may cause this, however it is suspected that the risk of this is much less than with unfractionated heparin.

Once low molecular weight heparin has been administered, it cannot be reversed.  Unfractionated heparin lasts in the body a much shorter period of time and there are medications that can reverse its effects.

The biggest risk with any heparin compound is that of hemorrhage.  Even though low molecular weight heparin is administered at home by injection instead of in the hospital by vein, the effect on clotting elements is similar and the risk of bleeding persists.  Therefore, it must be monitored closely by trained personnel, and if there is any trauma or surgery planned, it must be stopped in advance to decrease the risk of adverse bleeding.

There are several different low molecular weight heparins available in the United States.  Each differs and therefore, the dosage schedule also differs.  They may not be interchangeable depending on the indication that the drug is prescribed.

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Last modified: May 17, 2010