anti-coagulant question

Never2late1 · Jun 17, 2008

here is what i found from wiki "warfarin and related coumarins decrease blood coagulation by inhibiting vitamin k epoxide reductase, an enzyme that recycles oxidated vitamin k to its reduced form after it has participated in the carboxylation of several blood coagulation proteins, mainly prothrombin and factor vii. for this reason, drugs in this class are also referred to as "vitamin k antagonists".

basically vitamin k is antidote of warfarin, aspirin and dipyridamole are antiplatelet

nrsang97, BSN, RN · Jun 17, 2008

Asprin is contraindicated in asthmatics as many are sensitive to asprin and asprin containing products.

Vitamin K is the antidote to coumadin. Protamine sulfate is the antidote to heparin.

We teach someone who will go home on coumadin, ( a fibber for example) to limit green leafy veggies due to the fact that the vitamin k in them will limit the effect of coumadin.

leslie :-D · Jun 17, 2008

Why is vitamin K contraindicated with Warfarin, but not with other anti-coagulants like dipyridamole and aspirin?
Also, I read somewhere that dipyridamole and aspirin together (agrenox) was to be used with caution with asthmatics and such. I cannot come up with any reasons for this. My Davis drug book doesn't always expand as much as I would like it to sometimes. It is awesome, but I would like even more detail if there are better books available.

it has been my understanding that meds such as asa, plavix, ticlid, aggrenox, act as an antiplatelet on arterial clots:

and coumadin is used directly for venous clots.

vit k wouldn't affect arterial clots but would affect venous ones.

there is some asthma that is a result of asa sensitivity/allergy.

that is why strong precautions are given to asthmatics in taking any products that contain asa.

leslie

Virgo_RN, BSN, RN · Jun 17, 2008

nrsang97 has it right.

Warfarin inhibits vitamin K dependent clotting factors, so vitamin K is the antidote. Some people with asthma are sensitive to ASA.

My understanding though, is that it's not necessary for people on warfarin to limit their leafy green veggies, but to keep their daily consumption of them consistent.

NurseNature · Jun 17, 2008

Thanks to all! So, if many asthmatics are sensitive to asa, how about COPD-ers, pneumonia, etc...?

NurseNature · Jun 17, 2008

it has been my understanding that meds such as asa, plavix, ticlid, aggrenox, act as an antiplatelet on arterial clots:
and coumadin is used directly for venous clots.
vit k wouldn't affect arterial clots but would affect venous ones.
there is some asthma that is a result of asa sensitivity/allergy.
that is why strong precautions are given to asthmatics in taking any products that contain asa.
leslie

Why would it effect one and not the other - in regards to venous vs arterial? I think I am missing something here, or possibly part of my brain.

Virgo_RN, BSN, RN · Jun 17, 2008

Why would it effect one and not the other - in regards to venous vs arterial? I think I am missing something here, or possibly part of my brain.

It wouldn't. You're not missing anything.

Think about it. Warfarin is used for the prevention of thrombus formation in people with A-Fib. Why? Because if a clot forms in either of the atria, then travels through the ARTERIAL system to the brain, the person can have a stroke.

leslie :-D · Jun 17, 2008

Why would it effect one and not the other - in regards to venous vs arterial? I think I am missing something here, or possibly part of my brain.

from what i've learned, arterial clots are comprised mostly from platelets that stick against the vessel walls.

with venous clots, they are comprised mainly of clotting proteins:

platelets play a minimal role in venous clots.

occasionally, arterial clots originate from one of the left heart chambers, resulting in a-fib.

although this type of clot is an arterial embolism, it resembles the types of clots seen in veins...again, w/minimal platelet activity.

therefore, afib is best treated w/coumadin, and not your typical antiplatelet meds.

so, arterial thrombus = platelet formation

venous thrombus = clotting proteins

thus, the difference in med administration.

leslie

notadoc · Jun 17, 2008

nrsang97 has it right.
Warfarin inhibits vitamin K dependent clotting factors, so vitamin K is the antidote. Some people with asthma are sensitive to ASA.
My understanding though, is that it's not necessary for people on warfarin to limit their leafy green veggies, but to keep their daily consumption of them consistent.

This is exactly right. Maintaining a steady intake level of Vitamin K is more important than trying to limit intake. First off, although green leafy vegetables contain the highest levels of Vitamin K, they are far from the only sources of it. Attempting to eliminate (or even severely restrict) Vitamin K in the diet make for a very boring diet, since almost everything contains at least a little Vitamin K. More important, though, is the fact that something like half of the Vitamin K in our bodies is produced by bacteria in the intestines.

All this being said, dietary consistency is important. Unusually increased Vitamin K intake (say, a slightly paunchy nursing student deciding to "get healthy" by eating salad every night for a week when the "normal" salad intake is more like one every leap year) can cause a clinically significant drop in the patient's INR. Likewise, an unusually low intake over more than say a week or so can lead to a clinically significant increase in INR. Consistency is key, especially in "stable" warfarin patients that may only get their INR checked every four to six weeks. Warfarin is a really messy drug to work with (and to take). Hope this helps.

notadoc

leslie :-D · Jun 17, 2008

here is what i found from wiki "warfarin and related coumarins decrease blood coagulation by inhibiting vitamin k epoxide reductase, an enzyme that recycles oxidated vitamin k to its reduced form after it has participated in the carboxylation of several blood coagulation proteins, mainly prothrombin and factor vii. for this reason, drugs in this class are also referred to as "vitamin k antagonists".
basically vitamin k is antidote of warfarin, aspirin and dipyridamole are antiplatelet

this has been the most concise response, and actually answers the op's question.

leslie

Virgo_RN, BSN, RN · Jun 17, 2008

from what i've learned, arterial clots are comprised mostly from platelets that stick against the vessel walls.
with venous clots, they are comprised mainly of clotting proteins:
platelets play a minimal role in venous clots.

OK, that part makes sense.

occasionally, arterial clots originate from one of the left heart chambers, resulting in a-fib.

A-Fib is the result of ectopy in the conduction system of the heart. A-Fib does not result from clot formation, but vice versa. Clots do not form in one of the left chambers, they form in one of the upper chambers, or atria.

although this type of clot is an arterial embolism, it resembles the types of clots seen in veins...again, w/minimal platelet activity.
therefore, afib is best treated w/coumadin, and not your typical antiplatelet meds.

Thrombus formation in A-Fib is related to the lack of atrial kick, or ejection of blood, from the atria during contraction, because the atria are essentially quivering. This leads to a relative stasis of the blood in the atria, which facilitates thrombus formation, so, this part does make sense. Thanks for clarifying.

A-Fib is not treated with warfarin. The potential complication of stroke is prophylactically treated with warfarin. Treatment of A-Fib is with antiarrhythmics or cardioversion, and many cases of A-Fib are not treated.