Question about Heparin

[Je062787]

Hello:

I'm taking pharmacology and am very confused with Heparin. Our teacher (who is a pharmacist) lectured in class, stating that Heparin (unfractionated) is used for prevention of blood clots. There is also another class of Heparin which consists of LMWH (ex: Lovenox). She said this can be used for prevention AND activity (with more emphasis on Factor Xa, which is a clotting factor), for example, surgical prophylaxis and active DVT. But I'm not sure what "activity" she is referring to, because she said that it is not a thrombolytic, which lyses blood clots. To me, "activity" means that it lyses the clot. My questions are:

1.) If LMWH is used for "activity", and for active PE, what exactly does it do, if it doesn't lyse the clot?

2.) IV heparin is used for clots. Does this mean Lovenox can be used in the IV?

Thank you!

[NICUismylife, ADN, BSN, RN]

I'm guessing you are 1st semester. I know it's hard to recognize the tone of a post at times, so I will preface this with saying that I say this in a kind way: You need to learn to utilize your resources. The answers to your questions can be found in your drug book in less time than it probably took to write your post. Both heparin and enoxaparin are anticoagulants, both can be used for DVT prophylaxis, both can be used when a clot is present, neither will lyse the clot (TPA is needed for clot lysis). I've never seen enoxaparin given IV, however the drug book states that it can be given via IV bolus in the case of acute MI. A patient cannot go home on heparin, they can go home on enoxaparin, or they can be switched over to warfarin (most common), but since it takes 72 hours for warfarin to take effect, they continue on enoxaparin until the warfarin reaches a therapeutic level based on INR.

As far as your instructor referring to enoxaparin being more "active" she is probably referring to the mechanism of action. Which in the drug book states "drug has a higher antifactor-Xa-to-antifactor-IIa activity ratio than heparin." -Nursing 2015 Drug Handbook

You could also ask your instructor for clarification, but I guarantee you, she'll want to hear that you checked your references on your own before you approach her.

[Lev, MSN, RN, NP]

I have only ever seen lovenox given subcutaneously. It is much longer acting than Heparin. Lovenox is frequently used prophylactically after orthopedic surgery to prevent clots. Patients go home on lovenox or aspirin. Heparin is more frequently used for existing pulmonary emboli and deep vein thrombosis. Lovenox can be used to bridge to coumadin which takes a couple days to be therapeutic - give lovenox (shorter acting) until coumadin is in full force. At low doses, heparin inactivates factor 10a and prevents conversion of prothrombin to thrombin, however at higher doses it inactivates factors 9-12 +thrombin and inhibits conversion of fibrinogen to fibrin. Lovenox works by inhibiting factor 10a.