Pharmacotherapy Newsletter

Volume 1, Issue 17, 05/11/2009

Question

Why is the low molecular weight heparin, enoxaparin (Lovenox®) dosed in mg while the other LMWH's (dalteparin (Fragmin®) and tinzaparin (Innohep®)) are dosed in IU/kg and is this difference clinically relevant?

Answer

Low molecular weight heparins (LMWH) are used for a variety of cardiovascular conditions and offer many advantages over traditional unfractionated heparin (UFH).  The three most commonly prescribed LMWH are enoxaparin (Lovenox®), dalteparin (Fragmin®) and tinzaparin (Innohep®) of which enoxaparin is most commonly used in clinical practice.^1-3  While the ultimate choice of which LMWH to use may be influenced by the approved indication, the ease of use and dosing are also important factors in clinician acceptance.  As such, if a medication is complicated to prescribe, dispense and/or administer, then healthcare systems and clinicians are likely to perceive an increase in risk for human error.  This is especially true if a medication's dose falls outside of the normal medical nomenclature recognized by most healthcare providers and if the drug requires more than one mathematical calculation to be performed prior to dispensing and/or administration.  While LMWH do offer many benefits over UFH, their dosing can appear complicated or confusing to many clinicians.