Morningstar wrote:
rachel wrote:
Asprin only thins the blood in lower doses than are used for pain medication. at higher doses it also acts as a coagulant, cancelling out its anticoagulant effect. I wont explain in any more detail unless you really want to know, i try not to bore people too often, but thats why i was wondering.
Interesting. My daughter goes into surgery this Wednesday and her doctor told me no aspirin, no advil, no NSAIDs for 10 days prior to the surgery. And, she specifically stated that it was because such drugs could interfere with the proper clotting of the blood. I will have to ask her about your statement, Rachel. Because, my daughter lives on Advil for her migraines and got quite upset that she had to temporarily switch to tylenol.
First off, for my referance advil is Ibuprofen and tylenol is Acetaminophen, or paracetamol in the UK.
i wish i still had my pharmacology notes, but i've leant them to someone. anyway, i've checked in my pharmacology text book instead.
NSAIDS (of which asprin is one) all inhibit an enzyme called COX. This effects different cells in different ways depending on what downstream effects this has, as COX is part of a complex pathway and each cell makes different enzymes further down the pathway.
blocking COX in platelets inhibits platelet aggregation and vasovonstriction - ie stops blood clotting.
Blocking COX in the bloodvessel endothelium inhibits vasodilation and removes the inhibition of platelet aggregation - ie causes blood clotting.
Normally this is ok as the effects "cancel themselves out" but asprin is a different case because it's effect is permanent on COX. it covalently binds to the enzyme, as opposed to ibuprofen for example, which competes with COX's substrate for the active site on the enzyme. This irreversible effect is normally fine as the cell can just make new COX, but in platelets this cant be done as they're non-nucleated cells, so cannot make new enzymes - the only way of replacing the activity of COX is to make new platelets. So once the endothelial cells have remade their COX (the timescale is in the region of hours, i dont remember exactly how long) you only have the effect of inhibiting COX in the platelets - which is to inhibit clotting, so you can get the side effects of excessive bleeding which is why you're advised not to take it during surgeries.
what your daughters doctor has said about NSAIDs interfering with blood clotting is true, so i can see why they reccommend her not taking then before the operation so that there isnt any left in her blood stream. i'm slightly confused as to why he's said no NSAIDs but said that tylenol is ok... it does make sence, but its a bit contradictory as paracetamol (tylenol) is also an NSAID, it just works in a different way.
Have i answered your question? i feel like i've just waffled really...
Does the tylenol help her migranes? because if it doesnt you should ask her doctor if she can take anything else in the run up to the surgery, as they may be reluctant to prescribe her something else all the time, but might be willing to for a short period of time, 5HT inhibitors possibly, i know they're used for migranes.