Choosing anticoagulants

[Apoplexy__]

A couple questions here:
-If LMWH is basically a better version of heparin in every way (except risk in kidney disease), why do we ever use heparin?
-When do we use Factor Xa inhibitors over other anticoagulants?
-Why can't we formulate injectable non-monitored anticoagulants for outpatient use the way we do with insulin?

Any elaboration and related info is also appreciated.

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[Cytarabine]

A couple questions here:
-If LMWH is basically a better version of heparin in every way (except risk in kidney disease), why do we ever use heparin?
-When do we use Factor Xa inhibitors over other anticoagulants?
-Why can't we formulate injectable non-monitored anticoagulants for outpatient use the way we do with insulin?

Any elaboration and related info is also appreciated.

The below may not be entirely correct, but is what I've kind of picked up. With that said, I've yet to see unfractionated heparin used - pretty much every patient I've taken care of gets Lovenox.

Unfractionated heparin is more easily titrated and reversed. It's also indicated (for reasons I'm not aware of) over LMWH for things like anticoaguation prior to rhythm control in afib w/clot.

Xa inhibitors are an option for treatment of / continuation of anticoagulation s/p HIT.

I think Lovenox is occasionally given to pts for use outside of the inpatient setting.

 

[SouthernSurgeon]

Do you mean for prophylaxis or treatment or both?

There are a number of reasons, with varying levels of legitimacy.

The first is simply practice inertia.

The second is cost - both relative cost of the drugs and the relative costs of the monitoring.

There is a general fear of LMWH when someone is potentially going to need a procedure since it is longer acting and often not directly monitored.

For treatment some hospitals don't regularly run anti- Xa levels - our like our VA only run them M-F (wtf). Although the data doesn't support this, some people get concerned about getting to a therapeutic level quickly enough with lovenox.

Those are a few of the reasons. As to your other questions:
- we do send people home on lovenox injections without routine monitoring both for treatment of DVT and for prophylaxis in high risk populations. But for someone who will need longer term anticoagulation it is more convenient for the patient to use an oral agent.
-the Xa inhibitors have a rapidly growing role - Xarelto and pradaxa especially. They are very new agents (were not in use at all when I graduated med school). They are acceptable for treatment of DVT and for afib. Cardiologists seem to be in love with them as they are oral agents that don't require monitoring. They are not just for use in patients with HIT as the above poster said (fondaparinox is used for HIT and argatroban - a direct thrombin inhibiyor). The major concern with Xarelto and pradaxa is the lack of an effective reversal agent. There have been some reports out of Europe of increased rates of intra cerebral hemorrhage with these agents. There is currently a brewing controversy that one of the drug's manufacturers may have withheld knowingly that monitoring the drug levels could lead to more effective therapy and reduced risk of bleeding, so there is also that.

 

[Apoplexy__]

Thanks @Cytarabine and @southernIM!

An underlying curiosity to my questions was essentially how much of the choice of anticoagulants was practice inertia -- so you very nicely answered that. I was referring to both treatment and prophylaxis in my confusion, but honestly I think that pretty much clears things up for me.