Seizure meds and regulating blood thinners

[Geofd]

Hello out there,I'm gonna have surgery to repair/replace my mitral valve the options a have are,Dr says he's going to try to sew broken leaflet cords, to stop leakage, or repair or replace the valve,he explained everything, and need to make a decision as to which surgery I want tissue/mechanical,I'm on anti seizure meds, he mentioned that it can be hard to regulate blood thinners while one theses meds has anyone experienced this is it a big deal thanks to everyone

 

[Chuck C]

Hi Geofd.
Drugs that interfere with warfarin uptake usually interact with the P450 system and are classified as either inhibitors or inducers. Many anti-seizure drugs are inducers, which means that they would speed up the metabolism of warfarin from your system, resulting in needing a higher dose of warfarin to maintain target INR.
I am not on an anti-seizure drug, but I was prescribed amiodarone upon release from the hospital. Amiodarone is a P450 inhibitor and, as such, delays the metabolism of warfarin. It caused a major spike in my INR initially, something the prescribing nurse and pharmacist failed to warn me about. Ultimately my dosage of warfarin was adjusted and reduced by about 40% in order to counter the inhibitory effects of warfarin clearance by the amiodarone. Once I got the dosing right to keep me in the proper INR range, my INR remained very stable.

If the medication that you are on is, in fact, a P450 inducer, your system will metabolize warfarin quicker and more warfarin would be needed to keep INR in range. I would imagine that it would just be a matter of finding the right warfarin dose and would think that stability could be achieved once you get the dosing right. Hopefully someone with experience with warfarin and anti-seizure medication can chime in to share if this is the case, as I am just speculating based on my experience in achieving stability with a drug that was a P450 inhibitor.

Having said that, even if you are able to dose the right amount of warfarin to counter the quicker warfarin clearance, if one is prone to seizures the bigger concern may be the risk of having a seizure which leads to a head injury, which can be very serious or even fatal when on anti-coagulation.

From the Epilepsy Foundation:

"Anticoagulation always carries risks, but the risks are greater for people with epilepsy. Regardless of the antiepileptic drugs (AEDs) taken, the risk of prescribing anticoagulants chronically to epilepsy patients is increased because of the danger of falling during a seizure. A patient who falls and suffers head trauma while taking anticoagulants has a greater likelihood of intracranial bleeding."

https://www.epilepsy.com/living-epi...orders/anticoagulant-and-antiplatelet-therapy

 

[Geofd]

Hi Geofd.
Drugs that interfere with warfarin uptake usually interact with the P450 system and are classified as either inhibitors or inducers. Many anti-seizure drugs are inducers, which means that they would speed up the metabolism of warfarin from your system, resulting in needing a higher dose of warfarin to maintain target INR.
I am not on an anti-seizure drug, but I was prescribed amiodarone upon release from the hospital. Amiodarone is a P450 inhibitor and, as such, delays the metabolism of warfarin. It caused a major spike in my INR initially, something the prescribing nurse and pharmacist failed to warn me about. Ultimately my dosage of warfarin was adjusted and reduced by about 40% in order to counter the inhibitory effects of warfarin clearance by the amiodarone. Once I got the dosing right to keep me in the proper INR range, my INR remained very stable.

If the medication that you are on is, in fact, a P450 inducer, your system will metabolize warfarin quicker and more warfarin would be needed to keep INR in range. I would imagine that it would just be a matter of finding the right warfarin dose and would think that stability could be achieved once you get the dosing right. Hopefully someone with experience with warfarin and anti-seizure medication can chime in to share if this is the case, as I am just speculating based on my experience in achieving stability with a drug that was a P450 inhibitor.

Having said that, even if you are able to dose the right amount of warfarin to counter the quicker warfarin clearance, if one is prone to seizures the bigger concern may be the risk of having a seizure which leads to a head injury, which can be very serious or even fatal when on anti-coagulation.

From the Epilepsy Foundation:

"Anticoagulation always carries risks, but the risks are greater for people with epilepsy. Regardless of the antiepileptic drugs (AEDs) taken, the risk of prescribing anticoagulants chronically to epilepsy patients is increased because of the danger of falling during a seizure. A patient who falls and suffers head trauma while taking anticoagulants has a greater likelihood of intracranial bleeding."

https://www.epilepsy.com/living-epi...orders/anticoagulant-and-antiplatelet-therapy

Thanks for your response,the seizure disorder is due to scare tissue from an old accident ,the Dr aren't sure if I even need I anymore but I would have to stop work and driving for 6 weeks and be off the meds, no seizures since1979-1980 I will check to see if what I'm taking is p450 inhibitor

 

[Juli]

I am on seizure meds now for three years (Keppra) and have a mechanical valve for five. I do not recall any change in my Warfarin dosage and if there was I would be able to measure and adjust.

 

[pellicle]

I want tissue/mechanical,I'm on anti seizure meds, he mentioned that it can be hard to regulate blood thinners while one theses meds has anyone experienced this is it a big deal thanks to everyone

generally speaking most GP's and many surgeons have something barely above zero actual experience in managing anyones INR ... no joke. Like most people they remember the bad news but seldom the plain sailing.

I believe that its entirely possible to regulate your INR with any medications, and even easier if they are taken consistently.

So don't let that put you off a mech valve if you would like to go that way. Please mention the specific drug and I'll have a look into it. Either way reach out if you want assistance in managing INR when the time comes. In the mean time I wrote this some years back as a guide and reference.

http://cjeastwd.blogspot.com/2014/09/managing-my-inr.html
The only thing to strictly avoid is Grapefruit
http://cjeastwd.blogspot.com/2021/05/grapefruit-and-warfarin.html

 

[Geofd]

Thanks , phenobarbital 3 times a day and tegrotal
3 times a day ,do you need the doses????

 

[pellicle]

phenobarbital

ok, so first hit:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2151101/

Phenytoin, carbamazepine and phenobarbital are potent inducers of the cytochrome P450 system, and their interactions with warfarin have been known for decades.​

so that's pretty clear and significant. So it then goes on to say

These drugs can substantially increase the rate at which warfarin is metabolized and thus reduce the effect of a previously adjusted dose. Likewise, sudden withdrawal of any of these drugs may decrease the rate at which warfarin is metabolized​

so what this is saying is that if you are consistent with your doses of phenobarbital (meaning you take the same dose and don't miss them) that INR management is possible.

Are your doses consistent (within a 24 hour time)? If you always take the same dose (in a 24 hour period) of phenobarbital then it is simply a matter of determining dose of warfarin by measuring INR and dosing according to the desired INR. The dose of warfarin is irrelevant, the intention to administer warfarin is only the INR.

 

[Geofd]

Thanks everyone for your responses yes I am good about taking my meds this sounds doable

 

[tom in MO]

Hello out there,I'm gonna have surgery to repair/replace my mitral valve the options a have are,Dr says he's going to try to sew broken leaflet cords, to stop leakage, or repair or replace the valve,he explained everything, and need to make a decision as to which surgery I want tissue/mechanical,I'm on anti seizure meds, he mentioned that it can be hard to regulate blood thinners while one theses meds has anyone experienced this is it a big deal thanks to everyone

I would suggest asking the doctor who prescribes your seizure medications. They may know more about your condition, the specific drug and the problems with warfarin. I asked two of my doctors similar questions before picking a mechanical valve.

 

[Geofd]

I would suggest asking the doctor who prescribes your seizure medications. They may know more about your condition, the specific drug and the problems with warfarin. I asked two of my doctors similar questions before picking a mechanical valve.

Thanks,just had the surgical consult, Dr says there's a 95% chance it can be repaired so at this point I'm leaning toward a mach valve he gets in there and sees that he can't repair it