Fast vs. slow metabolism of warfarin

[catwoman]

This is probably best answered by Al Lodwick:

We read that activity speeds up metabolism of warfarin and that you will need more warfarin if you exercise a lot, bicycle regularly, swim competitively, etc.

But ... WHY?

What biochemical/whatever explanation is there for the dynamics of metabolism that increases utilization of a substance with an increase in activity? Is less warfarin actually absorbed by the liver?

I have always been interested in the WHY of anything. Also, the WHO, WHAT, WHEN & WHERE... which is why I became a journalist.

 

[KristyW]

Here's a very basic explanation about activity/exercise & the metabolism of warfarin.

The liver is a filter for our blood supply. Warfarin is a medication that is carried in the bloodstream and is filtered out (over time) by the liver. The way to increase the number of "trips" through the liver is to increase the heart rate. Exercise/activity increases the heart rate. Therefore the warfarin is "filtered" out more quickly with exercise.

Hope this makes sense.

 

[Guest]

Hey Kristy,

Do you want a job in a Coumadin Clinic in Pueblo?

 

[catwoman]

Here's a very basic explanation about activity/exercise & the metabolism of warfarin.

The liver is a filter for our blood supply. Warfarin is a medication that is carried in the bloodstream and is filtered out (over time) by the liver. The way to increase the number of "trips" through the liver is to increase the heart rate. Exercise/activity increases the heart rate. Therefore the warfarin is "filtered" out more quickly with exercise.

Hope this makes sense.

Kristy:

That's what I've always read. And I understand that explanation.

Am interested in seeing an explanation by a pharmacist or college professor or some sort of high-falutin' person.

 

[Guest]

I have forgotten Kristy's exact title but I know that she works in a dental office. That is high falutin enough for this answer.

 

[catwoman]

Al:
OK. I'll buy that.

I'm the kid who always asked, "Why?" when the teacher or my mother said something. I had to UNDERSTAND the request or statement, more than just at face value.
Still do.

 

[Guest]

I believe that the more people understand their medications, the more likely they are to take them correctly.

 

[Bill B]

Here's a very basic explanation about activity/exercise & the metabolism of warfarin.

The liver is a filter for our blood supply. Warfarin is a medication that is carried in the bloodstream and is filtered out (over time) by the liver. The way to increase the number of "trips" through the liver is to increase the heart rate. Exercise/activity increases the heart rate. Therefore the warfarin is "filtered" out more quickly with exercise.

Hope this makes sense.

Although it has been years since this thread was posted, I need to correct this. Liver blood flow does not affect warfarin metabolism. There are some drugs for which this is true. These are called "high clearance" drugs; ones for which the liver is very efficient at removing, so that the more the liver sees, the greater the removal rate. Warfarin is not one of them. Also, even if it were, exercising you skeletal muscles does not increase liver blood flow. Instead more blood is shunted to the muscles and away from the liver.

 

[Protimenow]

Blood flow through the muscles, instead of through the liver, might be worth considering when evaluating any effects that exercise has on INR, but I think we may be missing the point.

Excessive activity can result in dehydration - it can result in increases in lactic acid and other byproducts of exercise, and it may even influence the microflora in our gut that break down warfarin before the liver even gets to it.

Going through my INR Diary, I actually didn't find anything that strongly suggested a direct cause and effect relationship between my own excessive activity and changes in INR -- but I had the sense that there WAS a relationship between dehydration and INR.

I'm personally not quite comfortable making a statement that exercise has NO relevance to INR changes.

 

[H.E.pumper]

"Excessive ativity" ??? I didn't think there was any such thing as 'excessive' activity. For those of us who participate in activities that produce lactic acid episodes, well, that's a good thing in my opinion because our 'excessive' activity is making us stronger. "microflora in our gut" ??? Geez!


Sorry for the sarcasm...and, seriously, Thank You Protimenow for showing me that your excessive exercising :smile2: has not affected your INR regiment. I'm presently in the deciding Mechanical vs Biological stage for my upcoming AVR job in June and your post was very valuable to me.

Tom

 

[Protimenow]

Regiment? No, I don't have a regiment doing my exercise for me - I just do it myself.

As far as excessive -- that's simply in relation to my normal state of relative inactivity.

This thread, started an eon ago, was trying to answer why (or if) exercise will influence INR. And, yes, if antibiotics can do tihing to our gut that cause warfarin breakdown rates to change, why can't dehydration?

In any case -- your decision about mechanical versus tissue is often one related to your current age and how long you want to live. I opted for a mechanical when I was in my early 40s -- if I was 20 or 30 years older, my decision may have been different. There are probably a lot here who can give you advice - or personal opinions about what's best for you - and technologies for both mechanical and tissue valves have improved since my surgery -- and there may even be less invasive fixes for your valve.

It'll be good to hear what you decide and perhaps even why.

 

[H.E.pumper]

Thanks for the quick replay Protimenow; I've beem lurking here for about a week or so and so far every aspect of my decision making process has been covered every which way on this forum, not suprisingly though. I'm a very sports active, retired 63 year old with severe aortic stenosis and I'm leaning toward the mechanical primarily because I don't want to have a second OHS to replace the biological valve when I'm really old. I have an appointment with my surgeon at the Cleveland Clinic this coming Friday.

Tom

 

[Protimenow]

The Cleveland Clinic is certainly one of the best, from what I'm reading.

The mechanicals are supposed to have a lifetime guarantee -- certainly 50 or more years (supposedly). The tissue valves are supposed to be getting much better than they used to be, with some lasting as long as 15-20 years -- and with repairs down the road (perhaps) that won't require OHS.

Of course, if it was my choice, I'd listen to my specialists, discuss it with family (if they care), and be comfortable with whatever I choose.

(And I'm seeing a cardiologist - for the first time in at least six years - on Tuesday)