warfarin and digoxin interaction
Started by mmlau
What is an indication that warfarin and digoxin share? If they are used in combination to treat that condition, do you think there's a drug interaction? How about metabolism, are they metabolized via the same pathway?
They may both be used to treat atrial fibrillation. They are both substrates of CYP 3A4, however warfarin is a weak substrate of CYP 3A4, so there is probably not a major interaction, but that is just my opinion with my limited knowledge.
Anyone can feel free to correct me if I am wrong.
From what I know, there are no major drug interactions to be aware.
Well, technically, warfarin doesn't treat A-fib. But it prevents formation of blood clot which can occur with A-fib.
Regardless of possible interactions where one drug prevents metabolism of the other thereby increasing serum concentration of the drug, once doses are titrated and dig level and INR stablized, drug interactions shouldn't pose much problem.
Plugging both drugs into the 'Interactions' tab in Micromedex comes up with zero drug-drug interactions.
How sophisticated...
You've got a life-time subscription to Micromedex/Lexi/Epocrates and you know it! 😛
I want a life time subscription to that. How much does it cause for lifetime, and uptodate also?
Heh...well, I'm not aware such a thing exists. They probably made an exception for Priapism though 😉
One interaction is that both digoxin and warfrin are highly protein bound drugs so they compete for proteins. If digoxin outcompetes warfaring for the proteins then there is a higher level of free warfarin in the blood and this can increase digoxin's concentrations. This can lead to an increased bleeding time.
Sorry meant to say that increased free warfarin in the blood can increase warfarin's concentration not digoxin's.
Warfarin is highly protein bound, but I don't think digoxin is. The package insert says 25% protein bound. To be classified as "highly", I think you need to be 90-95% protein bound...
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