What amount of alcohol do people notice a change in their INR

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C

ckeogh

Member
Joined
Jan 7, 2023
Messages
13
Location
Ireland
Hi,

I'm just wondering at what stage if any do people notice alcohol affects their INR.

I've been on Warfarin a year now and have been hesitant to drink. I've only drank 3 times since and have noticed no change to my INR.

First two times were only maybe 2 or 3 pints but last week I was at a family wedding and had about 6 or 7 and expected to see a change but nothing.

Am I one of the lucky ones 😂?

Have people found that there is an amount that affects their readings or maybe sometimes it does and sometimes it doesn't?
 
AFAIK alcohol doesn't change my INR.

The warfarin/INR training I received in the hospital indicated the biggest risk to your INR when drinking with warfarin was getting drunk and throwing up your daily dose. That will change your INR.
 
Drinking alcohol changes my INR very little. Kind of a myth, except that there is a very rare genetic condition in which people don't clear alcohol well and for them it does affect their INR more than others. Perhaps using anecdotes from one or two of those individuals is where the myth started.

I'll share a story of how little alcohol affects my INR. Recently went to Hawaii with my wife to celebrate our 30th anniversary. As it was only 8 days, I decided not to bring my meter. Checked INR the day before we left- 2.8. My range is 2.0 to 3.0 and so I made no changes to my warfarin dose.

In Hawaii, I had at least 3 or 4 drinks in the evening daily. Much more than I normally drink. Hey, it's vacation and it's Hawaii. I tested my INR when we came back home and it was 2.2.

But why did my INR drop? I believe it was due to increasing my exercise level during the trip. My wife and I are pretty active and we exercise daily. Every day, we either did a long hike or, if no hike was planned for the day, did an hour of cardio running on the treadmill. Doing a daily treadmill is normal for me, but the hikes were long and grueling- they ranged from 2 hours to 6.5 hours. The final hike of 6.5 hours involved some significant challenges, due to elevation changes and difficult trail conditions. That was the day before we left for home. From previous experience, alcohol does increase my INR, but very little. However, my experience is that when I increase my exercise load it will affect my INR- causing it to drop. This is actually well documented in the medical literature.

This is the really cool thing about self testing. You don't have to wonder whether drinking alcohol affects your INR. You can find out by testing your level after a vacation or wedding, on which occasions people often drink more than usual, or so I've heard ;). And, you certainly don't need to stop exercising- just know that if you significantly increase your exercise level, it would be a good idea to check your INR and make any adjustments to warfarin that are needed.

But, as has been said, don't drink so much that you throw up your warfarin dose or fall down and hit your head. We could add to that list- don't drink so much that you jump off your roof, thinking that you are Superman, decide that it would be fun to drive your car down the road like a video game or get into a fight with John Jones, heavyweight world MMA champ ect ect. You get the idea.
 
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The times when I have a reasonable change to the amount of alcohol I consume are usually holidays, but there are other factors such as diet changes that make it difficult to work out how much of the increased INR I get is down to the booze.

But as @Superman says: why worry? Test and get the next round in once you have adjusted your Warfarin dose!
 
Thanks for the replys.

No worry at all just more curious to see if many people notice the inr change. They make out like you can never touch a drink again.

From what I'm gathering it's just a case of not going to heavy anymore, but it's nice to know a few drinks is no problem.

It was getting very hard going out with friends and listening to them after pint 3 or 4 and I'm having a 0.0's 😂🍻
 
I did an analysis on this including the mechanism on how alcohol might affect INR a few years ago. Whereas warfarin works slowly with a half-life of about 40 hours if I'm remembering correctly; alcohol is metabolized in a linear process in a matter of a few hours, then it's effects on warfarin are gone, unless of course you keep drinking. But if you limit yourself to only a couple of drinks the effects quickly wear off. So I concluded it was negligible at that level of imbibing.
 
Hi

delucadana said:
I did an analysis on this including the mechanism on how alcohol might affect INR a few years ago. Whereas warfarin works slowly with a half-life of about 40 hours if I'm remembering correctly; alcohol is metabolized in a linear process in a matter of a few hours, then it's effects on warfarin are gone, unless of course you keep drinking. But if you limit yourself to only a couple of drinks the effects quickly wear off. So I concluded it was negligible at that level of imbibing.
Click to expand...
not a bad idea, and I applaud your approach. But did you look at things like how alcohol effects P450 (which is the metabolism for warfarin) and look at the various ways that metabolism of alcohol occurs?

A good starter on that is here for the interested (underline mine)

The Chemical Breakdown of Alcohol​

Alcohol is metabolized by several processes or pathways. The most common of these pathways involves two enzymes—alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). These enzymes help break apart the alcohol molecule, making it possible to eliminate it from the body. First, ADH metabolizes alcohol to acetaldehyde, a highly toxic substance and known carcinogen.1 Then, acetaldehyde is further metabolized down to another, less active byproduct called acetate,1 which then is broken down into water and carbon dioxide for easy elimination.2​
​

Other enzymes​

The enzymes cytochrome P450 2E1 (CYP2E1) and catalase also break down alcohol to acetaldehyde. However, CYP2E1 only is active after a person has consumed large amounts of alcohol, and catalase metabolizes only a small fraction of alcohol in the body.1 Small amounts of alcohol also are removed by interacting with fatty acids to form compounds called fatty acid ethyl esters (FAEEs). These compounds have been shown to contribute to damage to the liver and pancreas.3​


Ultimately I agree with your conclusion which is IMO why we see such trends. There was a good post on this some years back, but sSadly this was mostly lost in the management of this site all that remains is a reference to it:
https://www.valvereplacement.org/threads/thanksgiving-meals-and-inr.43315/post-789736
however you can find the public accounting of that here:


Best Wishes
 
ckeogh said:
Hi,

I'm just wondering at what stage if any do people notice alcohol affects their INR.

I've been on Warfarin a year now and have been hesitant to drink. I've only drank 3 times since and have noticed no change to my INR.

First two times were only maybe 2 or 3 pints but last week I was at a family wedding and had about 6 or 7 and expected to see a change but nothing.

Am I one of the lucky ones 😂?

Have people found that there is an amount that affects their readings or maybe sometimes it does and sometimes it doesn't?
Click to expand...

Hi There,

I love a beer. To be honest, my drinking habits haven't really changed since being on Wafarin. I drink less post my OHS last year though.

I found having 2-3 beers doesn't increase INR.

During the Xmas period though, I discovered INR was a bit more challenging. I had to monitor my INR more closely as I was drinking more than I normally would with Xmas parties etc. During this period I did have a reading of about 4.5 (my highest ever reading) but with help from a member I managed to get it within range pretty quickly.

But outside of that, booze doesn't really change my INR. WIN WIN :)
 
pellicle said:
But did you look at things like how alcohol effects P450 (which is the metabolism for warfarin) and look at the various ways that metabolism of alcohol occurs?
Click to expand...
Yes, I looked at that and found that the CYP 2E1 gene family (ref: page 29 of http://www.columbia.edu/itc/gsas/g9600/2004/GrazianoReadings/Drugabs.pdf) is one of the players in metabolizing ethanol. There is also a table on page 44 of ref that puts warfarin half-life at 37 +/- 15 hours. But what happens* is that the alcohol unbinds some of the 99% of warfarin that is bound to blood proteins, thereby creating more of the free and active warfarin. What counts is how long this extra free warfarin is left unbound and that depends on the blood-alcohol concentration which diminishes rapidly over time as alcohol is metabolized.

* I don't remember my sources for this statement, and looking at the analysis it's not documented in there unfortunately, but the analysis includes numbers representing the increase in free warfarin concentration over time. For example with one standard drink (17.7 ml ethanol per drink) after one half hour free warfarin concentration increases by 346% relative to what it was before the drink (100%) and after 1 hour it's 204%, then back to 100% after 1.5 hours.
From my analysis for one drink:
1694707521776.png

If one drinks 4 beers in two hours, the warfarin increase is gone in 5.5 hours. (Your mileage may vary.) This is what lead me to conclude that alcohol effect is for the most part, negligible.
How should one think about the boost in warfarin that alcohol causes? Probably not like another dose of warfarin because 1) it is more like an IV injection than an oral dose, and 2) it is not dependent on metabolism to dissipate, rather it gets re-bound by proteins to its inactive state as soon as the alcohol is gone.

Okay, I just found the formula I used to calculate the change in Kd that alcohol induces. Kd is dissociation coefficient; it's a measure of the warfarin-protein binding affinity. Alcohol reduces the binding affinity so some warfarin becomes unbound. It should be noted that this is not the only effect alcohol has. For example alcohol diminishes the effect of vitamin K. Other things like garlic, CoQQ10, exercise, etc. moderate INR and alcohol may have an effect on one or more of those so it's too complicated to accurately predict. Furthermore, everybody's metabolism is different so we each metabolize alcohol slightly differently (depending on sex, body size, weight, blood volume) and warfarin differently etc. and if one has impaired kidneys or liver, his or her metabolism can be much different than people for whom those organs are healthy.
 
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pellicle said:
Hi


not a bad idea, and I applaud your approach. But did you look at things like how alcohol effects P450 (which is the metabolism for warfarin) and look at the various ways that metabolism of alcohol occurs?

A good starter on that is here for the interested (underline mine)

The Chemical Breakdown of Alcohol​

Alcohol is metabolized by several processes or pathways. The most common of these pathways involves two enzymes—alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). These enzymes help break apart the alcohol molecule, making it possible to eliminate it from the body. First, ADH metabolizes alcohol to acetaldehyde, a highly toxic substance and known carcinogen.1 Then, acetaldehyde is further metabolized down to another, less active byproduct called acetate,1 which then is broken down into water and carbon dioxide for easy elimination.2​
​

Other enzymes​

The enzymes cytochrome P450 2E1 (CYP2E1) and catalase also break down alcohol to acetaldehyde. However, CYP2E1 only is active after a person has consumed large amounts of alcohol, and catalase metabolizes only a small fraction of alcohol in the body.1 Small amounts of alcohol also are removed by interacting with fatty acids to form compounds called fatty acid ethyl esters (FAEEs). These compounds have been shown to contribute to damage to the liver and pancreas.3​


Ultimately I agree with your conclusion which is IMO why we see such trends. There was a good post on this some years back, but sSadly this was mostly lost in the management of this site all that remains is a reference to it:
https://www.valvereplacement.org/threads/thanksgiving-meals-and-inr.43315/post-789736
however you can find the public accounting of that here:


Best Wishes
Click to expand...

11/17/13 -- Stew with moose?
 
Hi Dana

a great post with good detail and data
Dana said:
. There is also a table on page 44 of ref that puts warfarin half-life at 37 +/- 15 hours.
Click to expand...
The half life of warfarin is indeed documented well in the literature. Personally I would have quoted MIMS on this:

Excretion. The terminal half-life of warfarin after a single dose is approximately one week; however, the effective half-life ranges from 20 to 60 hours with a mean of about 40 hours.​

Personally I go with making an "average" half life of 48 hours because the calculation is simpler (if not perfect, but then what is actually perfect). Then there is other factors (like S and R half lives and their respective strength of effect).

Dana said:
But what happens* is that the alcohol unbinds some of the 99% of warfarin that is bound to blood proteins, thereby creating more of the free and active warfarin.
Click to expand...

that's very interesting, and first time to read this. I've not thought it through past:

Pharmacokinetic mechanisms for drug interactions with Warfarin are mainly enzyme induction, enzyme inhibition and reduced plasma protein binding. It is important to note that some drugs may interact by more than one mechanism.​


Dana said:
What counts is how long this extra free warfarin is left unbound and that depends on the blood-alcohol concentration which diminishes rapidly over time as alcohol is metabolized.
Click to expand...

exactly

Its really good to be reading things like this here as I'm feeling less and less like the lone voice on this.

Thanks
 
I have been on warfarin since my aortic valve replacement (On-X) and aneurysm repair in December 2019. I have found alcohol to have no effect on my INR and drink the same as I did pre-surgery. I only drink beer. Generally, I have 2 beers a night Monday-Thursday. Friday I will usually drink 7-8 beers. 5 or so on Saturday and 4 on Sunday. Granted, I only test once a week on Wednesday mornings. But my numbers are almost always between 2-3. The only thing I find that can drastically change my INR is 1) hot weather; 2) heavy exercise. When I train for cross-county ski races, the INR drops. Hot weather pushes it up. I spiked during a trip to Mexico last spring. I was drinking more than usual but I suspect sitting in the 90 degree sun was the real driver. Cheers and good luck.
 
Pellicle:

You're definitely not the lone voice, but I suspect that a lot of the references and links to research are too daunting or flying over the heads (not to offend anyone) of many of those on the forum.
 
Protimenow said:
but I suspect that a lot of the references and links to research are too daunting or flying over the heads (not to offend anyone) of many of those on the forum.
Click to expand...
agreed ... but there are few that argue based on data, evidence and the underlying science. I'm glad there is at least one more now (than there may have been before).

:)

ps: typing the @ then without any space starting with pell of pellicle will produce a popup menu (wherefrom you can select my name) to ensure I get a "mention" (that's a "mention" not just a mention) and a notification
 
I've been on warfarin since I was 27yo... I'm now 46yo. When I was younger I used to go to music festivals with my friends, drink all weekend, then front up for an INR on Monday morning. It was always normal.
 
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