In one of the articles we discussed last week we saw a
little about the competitive nature of aspirin and ibuprofen and the
implication this had on the unique anticoagulant effect of low-dose aspirin
(81mg per day, not enteric coated). I thought this was interesting and wanted to
explore this a little bit more and look at the proposed mechanism involved.
Both aspirin and ibuprofen target COX-1 on platelets and inhibit
the catalytic site which converts arachidonic acid into thromboxane (TX) A2.
TXA2 is a potent platelet aggregating agent. The difference between the two
NSAIDs is that they bind in two different locations in a competitive manner.
More importantly though, is that aspirin has an irreversible effect on the
catalytic site whereas ibuprofen’s effect is reversible. As an example, if
ibuprofen is taken right before a low dose of aspirin the ibuprofen will leave
no room in the COX-1 channel for aspirin. After most of the aspirin is
metabolized and the ibuprofen is removed, COX-1 will be reactivated and TXA2
will continue to be synthesized leading to platelet aggregation. If aspirin is
taken first, ibuprofen will probably not bind to COX-1, and since aspirin’s
effect is irreversible, TXA2 will not be synthesized until new platelets are
formed. Below is an image showing the cascade inside the platelet and where
aspirin has an effect.
So, can you ever take low-dose aspirin and ibuprofen
simultaneously? The FDA recommends taking a single dose of ibuprofen either 8
hours before or 30 minutes after low-dose aspirin to maintain the
cardioprotective results.
Sources:
“Concomitant Use of Ibuprofen and Aspirin: Potential for
Attenuation of the Anti-Platelet Effect of Aspirin.”http://www.fda.gov/downloads/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/UCM161282.pdf.
Food and Drug Administration Science Paper. 8 Sep. 2006. Web. 30 Nov. 2014
Schuijt, MP et al. “The Interaction of Ibuprofen and
Diclofenac with Aspirin in Healthy Volunteers.” British Journal of Pharmacology
157.6 (2009): 931–934. PMC. Web. 30 Nov. 2014
Image: Gasparyan, A. Y. et al. J Am Coll Cardiol
2008;51:1829-1843
Wow, I knew that you shouldn't take them at the same time, but it is really interesting to see why!. Honestly, really makes me want to avoid medication, thinking about all the interactions that occur. After reading this, it definitely makes sense why people are put on aspirin after a cardiac event!
ReplyDeleteThanks for taking the time to go into a little more detail about the mechanism. It makes a lot more sense as to why these two would be problematic when taken together. The diagram is also very helpful. Thanks for the post!
ReplyDeleteI find it particularly interesting that it is recommended that one either takes Ibuprofen many hours in advance of taking aspirin or directly after. This was new to me. I think that it is very important to know for people who are taking it for cardiovascular protection.
ReplyDeleteI really enjoyed the picture that you included in your description of the how each of these work physiologically. Really simplifies and sums up the process. I never really thought about how each of these would affect each other, since the debate is usually between Tylenol and Advil.
ReplyDeleteNice post, the picture summarizes the actions of the enzymes very well, and you can tell that cox-1 inhibition causes repression of multiple products. The differences between the two NSAIDs is really interesting; i definitely didn't know that Ibuprofen and Aspirin bind to different spots on the cox-1 enzyme. The irreversible effects of aspirin are clearly understandable by your explanation.
ReplyDeleteThanks Jameson, This point was sort of confusing at our last class meeting. It is interesting to think of something like Aspirin having an irreversible change on a body structure. I wonder if, given no chance to bind COX-1, ibuprofen taken 30minutes after aspirin would have a greater effect on COX-2 than the same doseage without aspirin? I'd be interested to see that study done.
ReplyDeleteThe interaction between these two very commonly used drugs if very interesting. I had no idea that these two drugs acted so differently. I had no idea that aspirin caused an irreversible change. These kinds of things are really important to know if you commonly take these medications if you want get the maximal effect from them. Like you said if someone usually took ibuprofen before their aspirin then they are not really getting much effect from the aspirin.
ReplyDeleteThanks for sharing, Jameson! I think a lot of us know that its risky to take certain medications together, but it is always interesting to learn the mechanism and truly understand why. The diagram you utilized was also very helpful!
ReplyDeleteGreat post! This was presented an understanding of aspirin and ibuprofen that I would have no considered. I would have thought about their different interactions. I know my doctor has advised me to take a baby aspirin before flights because of a blood clotting disorder, and I would have never of thought about what would happen if I were to have taken aspirin to prevent clots, and perhaps ibuprofen if I were to have a headache. It is always important to be aware of and consider drug interactions and what goes into your body.
ReplyDeleteThanks for the post! Information like this reminds me of how important it is for physicians to remain abreast of current research in their fields and, to an extent, other fields. Talking to a patient about these interactions would be important for a physicians prescribing a low dose aspirin regimen considering how ubiquitous ibuprofen is.
ReplyDeleteThank you for the article! Since I don't take medicine, I always thought that ibuprofen and aspirin were basically the same thing since they are often used for similar problems. I never would have thought that ibuprofen and aspirin could be so different in the way they work when used together. But my dad and my sister depend on medicine quite a bit, aha. So I'll be sure to let them know in case they ever decide to use both drugs.
ReplyDeleteGreat topic choice! I think that this topic is very interesting and the drug-drug interactions in the body need to be studied more. That diagram is very helpful in depicting the mechanism. It seems to me that if these two drugs do interact across the same pathway and can influence the cardioprotective effects based on which is taken first should be labeled on the bottles. At low doses it is probably safe, but when someone is in need of the effects of aspirin and unknowingly takes a ibuprofen before instead of after the aspirin this can lead to bad results. Especially if they are taking the aspirin to prevent heart attacks.
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ReplyDeleteWhat I found most interesting was the irreversible vs reversible aspects of the two drugs. Like we talked about in class, I feel as if the majority of the population taking these common NSAIDs do not actually read the instructions. I looked into whether or not acetaminophen (tylenol) could have similar effects when taken with aspirin. The FDA provided a study showing that acetaminophen doesn't appear to interfere with aspirin's anti-platelet activity; the aspirin was taken in low doses for the study. I tried finding the mechanism in which tylenol works (similar to the one you posted) but could did not have any luck.
ReplyDeletehttp://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm125222.htm
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