protamine dose to reverse enoxaparin

[lalamcg]

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How do institutions reverse low-molecular weight heparin with protamine? Does anyone give bolus doses of Protamine >50 mg for enoxaparin doses >50 mg?

The Chest guidelines state that 1 mg protamine should be given to reverse 1 mg of enoxaparin (if enoxaparin was given within 8 hours). Chest does not list a max dose of protamine but I know the current protocol at my institution calls for a max 50 mg of protamine to be given (even if the patient had just received a dose of 100 mg of enoxaparin). Is this what most institutions are doing since the package insert for protamine gives a max dose of 50 mg within a 10 minute period? Would it be more appropriate to give a larger dose of protamine (e.g. 100 mg protamine for a patient who bled after enoxaparin 100 mg but just extend the amount of time it's infused over)?

It seems like the LMWH agents are tough because only 60% of enoxaparins anti-xa activity is reversed using protamine and I'm having a difficult time assessing the risk vs. benefit of giving a dose >50 mg of protamine uprfront vs. giving a max of 50 mg and waiting to see if the bleed advances before giving another dose of protamine.

Thanks for any insight you can offer!

 

[rxlea]

Don't you do like 0.5mg per 1mg enoxaparin 2-3 hours later?

I'm just a student but I seem to remember this from somewhere and don't have my notes in front of me right now

 

[lalamcg]

You're right. Most protocols I've seen say to give a smaller dose of protamine (0.5 mg per 1 mg enoxaparin) If the aPTT is prolonged after 2-4 hours, or re-bleeding occurs.

But altogether that's only 100 mg protamine and if you have a patient that just received 150 mg of enoxaparin you still haven't given the 1mg protamine per 1mg enoxaparin. I suppose you can keep giving the patient boluses of protamine every 10 minutes as needed if they keep bleeding... I'm just curious if anyone gives the whole calculation upfront in an extended infusion.

 

[rxlea]

You're right. Most protocols I've seen say to give a smaller dose of protamine (0.5 mg per 1 mg enoxaparin) If the aPTT is prolonged after 2-4 hours, or re-bleeding occurs.

But altogether that's only 100 mg protamine and if you have a patient that just received 150 mg of enoxaparin you still haven't given the 1mg protamine per 1mg enoxaparin. I suppose you can keep giving the patient boluses of protamine every 10 minutes as needed if they keep bleeding... I'm just curious if anyone gives the whole calculation upfront in an extended infusion.

I guess the problem is when you overshoot vs. not stopping the bleeding in a timely manner. I'd rather not overshoot and go with the 50, see what happens, and go from there. I haven't done kinetics yet but I guess it depends how long ago the patient received the enoxaparin...just thinking it through. Maybe one of our other regulars will chime in.

You could always stop the piggyback, though, if the aPTT returns to the appropriate range.

We have definitely put 100mg in a piggyback before at our hospital.I've made them.

 

[Busta919]

I am much more student than Rxlea (P1 to your P3/P4ness), but we were told that protamine sulfate was ~70% effective with LMWH. We did not discuss dosage, so I am also interested in the recommendation.

 

[rxlea]

I am much more student than Rxlea (P1 to your P3/P4ness), but we were told that protamine sulfate was ~70% effective with LMWH. We did not discuss dosage, so I am also interested in the recommendation.

We were told 80%.. I think it says 80 in the package insert. Either way, it's patient specific based on when the dose what taken and all that .I looked it up though...says 50 over 10 minutes and the effects persist for 2 hours...if bleeding not controlled or the anticoagulant effect rebounds, you can give repeated doses at 0.5 and give smaller doses if more than eight hours since enoxaparin dose

Edit : my therapeutics book says 60%

 

[pinipig523]

My understanding:

Protamine for Enoxaparin - 60% effective

Max dose for protamine is 50mg.

Dosing is dependent on when the last enox dose was. If < 8h then give 1:1 ratio with max at 50. If >8h then half the dose, max at 50.

Check Antithrombin Xa level - redose as necessary.