I'm used to regularly giving my blood and other blood components (plasma and platelets), but I was surprised the other day to see that one should not proceed to the donation if they consumed anti-inflammatory pills less than 8 days before. I understand how some painkillers may act as a blood thinning (e.g. the aspirin), but if I recall correctly, anti-inflammatory pills do not necessarily have that impact on blood. Then why is blood donation compromised if the donor recently consumed that kind of pills?
Although ACCP recommends 7- to 10-day aspirin intake cessation before surgery in patients with low cardiovascular risk, the results of our study suggest that aspirin intake cessation not longer than 96 hours can be adequate.
The recommendation to stop aspirin intake for 7 to 10 days is based only on the concern for the mature platelets during exposure to aspirin.
There are some mechanisms that may modulate the antiplatelet effects in the presence of aspirin and after aspirin cessation:-
Immature platelets, which are reticulated and larger, have less attenuated and more elevated platelet activity than mature platelets in the presence of aspirin. Moreover, the inhibition of human megakaryocyte cyclooxygenase with low doses of aspirin is incomplete, and megakaryocyte cyclooxygenase seems to recover within 12 hours after aspirin ingestion.
Interruption of the platelet function by aspirin results in the production of new platelets, presumably through the action of a feedback system controlling thrombocytopoiesis. These newly formed platelets may help in speedy recovery of the platelet activity.
These mechanisms above are responsible for speedy recovery of platelet activity before the average lifespan of platelets.
The concern for mature platelets (as I have mentioned in the quotation box) can also be applied to individuals before platelet donation i.e to wait for average lifetime of platelets which is 7-10 days (the duration which you are backing up in your question, without any reference, at least for me) before donation. Otherwise, according to who guidelines one must defer from donating blood 5 days after taking aspirin and 48 hrs after taking other NSAIDS (The blood bank nearby me defer from donating for 3 days).
Platelets has an average lifespan of 8-9 days. Taking meds like aspirin which is an anti-platelet forms a non-competitive bond with platelets rendering them useless to the rest of their lifespan. Hence, by the 8th of last dose of aspirin, you would have formed new healthy platelets good for donation.