Morning vs. evening anti-coagulation dose

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Ladybug

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Jul 30, 2019
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Mornings for me.

An anti-coag clinic I went to for a couple years had a sign on the wall stating to tell patients to take it in the evening. However, my Cleveland Clinic anti-coag clinic regularly asks if I have taken it yet when I get tested at 7:30AM
Are you glad you’re at the Cleveland Clinic.
 

Thomas

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I can't imagine the pain the family or any family that survives a relatives suicide goes through, for that matter.

I'm no scientist by any means but I've been wondering about splitting my dosage to morning and evening. The reason being (and here's the question) wouldn't it be better for your body to have a relatively consistent amount of warfarin in the system all the time as opposed to spiking the amount once per day and the body having to react? Or is this over micro managing?
 

LondonAndy

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Hi Thomas. I suspect that an excellent graph will be posted here shortly by Pellicle showing how Warfarin typically takes about 3 days to reach full effect and then start to decay in the blood stream, and so each day's dose will overlap and achieve the comparatively smooth level of anticoagulation you seek. In principle I think you would be right to say that splitting the dose into half in the morning and half in the evening, ie 12 hour intervals, would achieve an even more consistent level, so my amateur view is that there would be no harm in doing so but it would be a bit more of a faff.
 

Protimenow

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There's no harm in splitting the dose, but there's no reason to, either. It's not like an aspirin with a four hour half-life. Warfarin doesn't 'spike,' then taper off.

There MAY be some minor problems with splitting the dose between AM and PM. First, it's easier to forget one of the two doses during the day (unless you use a pill box - one for AM and one for PM. It's also probably more difficult to split your dose in half. For example, if your daily dose is 9 mg, do you get to this number by taking one 4 mg plus a 1 mg broken in half? And if you decide that it may make no difference if you take 5 mg in the morning and 4 mg at night, your INR may vary, based on the time of day that you test it.

Personally, I take my warfarin at night, near bedtime. Instead, I can take it at noon, or at 4 AM, or when I wake up - or any time, as long as I'm able to take the daily dose (without forgetting it), and it's best if the doses are about 24 hours apart (for once daily dosing).

Again, there's really no advantage to taking warfarin in split doses, twice a day.
 

tom in MO

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If you split the dose you have 2x as many chances to miss a dose :)

Really though, warfarin therapy is not an exact science and doesn't have to be. The INR is not a measurement of a physical property, like iron in your blood, but a ratio of coagulation rates. You have a target range not a target INR. If you are 0.1-0.2 out of your range, often no dose adjustment is needed, life will take care of it, but test in a week to make sure it did.
 

Protimenow

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INR is actually a ratio between the prothrombin time (the time that it takes for the blood to clot, using a standardized reagent), divided by a value for the specific reagent used. As long as the reagent value is accurate, INRs can be used as a standardized measure for coagulation rates. (An INR of 1.0 is 'normal' - a 2.0 means that it takes blood 2.0 as long to clot than a blood sample with an INR of 1.0. The numbers all relate to the 'normal' INR of 1.0.
 

Keithl

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This article shows the dose hits about 48 hours later and lingers for days. Although I will say I missed a day last week and my INR was down to 1.8 the next day then 2.0 for next 2 days before getting back up to 2.6. I usually bounce between 2.4 and 3.0 so was trying to figure out if I ate something that sent it down that far. Having an On-X and taking daily low dose aspirin I did not worry too much and took a low dose aspirin morning and night until I got back up to 2.6.
 

Bina

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Coumadin / warfarin has a very long half life in your body, most changes in dosing take 48 hours to show up in your INR readings.
Take it whenever is best for you to remember it.
I use a daily pill box and take my Coumadin with my dinner. If for some reason I forget to take it, then when I take my late night beta blocker I would see the missed Coumadin still in the pill box and take it right away. This has worked for 14 years.
 

pellicle

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I'm no scientist by any means but I've been wondering about splitting my dosage to morning and evening. The reason being (and here's the question) wouldn't it be better for your body to have a relatively consistent amount of warfarin in the system all the time as opposed to spiking the amount once per day and the body having to react? Or is this over micro managing?
to expand on Dicks answer:
yes, its over thinking it and applying an incorrect logic. The half life of warfarin is approximately 2 days, so what you took yesterday is still mostly there, as well as a good portion of the day before that and some of the day before that too, this is the actual reason why people "muse" that changes of INR response to dose do not become clear for a few days ... Compounding this is if you forget to take your morning dose would you take it with your evening dose?

So take it when you feel like however you feel like it, but just make sure you take it.
 

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