Plavix 75 and aspirin 81

[Jeanne1551]

I had an MI in July which was treated with angioplasty and 5 drug-eluding stents.  I was prescribed 75mg Plavix and 81mg.  Nothing about getting my blood levels checked was ever mentioned.  I understand this is necessary if a person is on Coumidin but do not know if it is needed when on Plavix.  Does anyone here know?

[kenkeith]

Without getting into the pharmocological aspects regarding the mechanism of action of asprin resistance and the mechanixm of activity of plavix (clopidogrel), the American Academy of Cardiology recommends tests.

Dr. Waksman:
"I'll try to do my best because it's a controversy. I don't think it's ready now for prime time, but we are starting to identify subgroups of patients who are high risk for stent thrombosis, because at the end of the day we want to know: Are we giving enough clopidogrel and aspirin to prevent stent thrombosis? And as we know, there are different levels of IPAs (inhibition of platelet aggregation). that has been measured with patients who are taking clopidogrel, and..."

There are studies about aspirin resistance and plavix resistance and there are studies that say it's 20-40% of the population. Other studies, at least with aspirin, it's about less than 1% if you use the arachidonic acid based (testing).

COX tests for aspirin, ADP for clopidogrel, two different tests two different pathways:
The current gold standard for plavix is challenging with ADP... challenging blood platelets with ADP and seeing if they aggregate. It is believed  that 40% is a threshold, but no one can prove that 40% is the threshold and there are patients that re-thrombose when they have 40% and we had majority who thrombose when it's lower than 10%.  Obviously, this does not translate to practical utility.

Currently, the general practice is to prescribe aspirin and plavix up to 1 year with drug enducing stents as there is some evidence of restenosis within that time frame.