Help needed with warfarin dosing in naive patients

[beachsaki101]

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Hi everyone,

I have a couple quick questions. If you hold a dose of warfarin, how much of the INR drop will you see? If you hold another dose of warfarin (2nd dose), how much will the INR drop?

Also, in initiating warfarin, after the first 3 days of warfarin and you get your first INR, how much of a rise in INR is appropriate in naive patients? What formula do you use during this time to give your next dose when you don't have a trend yet?

Thanks.

Beach

 

[WVUPharm2007]

We use a nomogram at work...kinda like the one in this guideline. There is a lot of subjectivity at work out in the field...I've never noticed a rhyme or reason to what half of the physicians prescribe half of the time when initiating warfarin. I dunno. And you will see a TON of variation from patient to patient. We had to give one guy 18mg of warfarin to get his INR to 2 a few weeks ago.

 

[VCU2011]

Hi everyone,

I have a couple quick questions. If you hold a dose of warfarin, how much of the INR drop will you see? If you hold another dose of warfarin (2nd dose), how much will the INR drop?

Also, in initiating warfarin, after the first 3 days of warfarin and you get your first INR, how much of a rise in INR is appropriate in naive patients? What formula do you use during this time to give your next dose when you don't have a trend yet?

Thanks.

Beach

I wouldn't use it clinically obviously because of the immense variation, but prof told us a good guess is INR would drop roughly a point a day if warfarin is skipped for a day.

As for your 2nd question, see WVU's answer

 

[ItsOverZyvox]

It's been over 10 years since I ran a coumadin clinic so I know I'm rusty. But I never used a nomogram or a formula to dose coumadin...rather I used to dose coumadin based on weekly dose then divided it by either 4,5,6, or 7 days and make the regimen work.

But there is so much patient variation on warfain PK, I don't know anyone of us can accurately predict the INR after a day or 2 of dose omission.