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Editor's Correspondence
October 28, 2002

Might Proton Pump Inhibitors Prevent the Antiplatelet Effects of Low- or Very Low-Dose Aspirin?

Arch Intern Med. 2002;162(19):2248. doi:

I read with interest the article on ulcer prevention in long-term users of nonsteroidal anti-inflammatory drugs (NSAIDs) by Graham et al.1 As the authors note, studies are needed to test whether a proton pump inhibitor can prevent life-threatening ulcer complications in long-term users of NSAIDs. They state that the ideal study should compare a proton pump inhibitor with or without low-dose misoprostol vs placebo, although such studies are unlikely to be realized if the cyclooxygenase 2 inhibitors prove to eliminate life-threatening NSAID ulcer complications. In this respect, further studies might be of interest. Aspirin and several other NSAIDs are weak acids that cross the mucosa in their lipid state. The suppression of acid production reduces the lipophilic nature of these drugs and, theoretically, might reduce their absorption and bioavailability. I wonder if there is need for concern that concurrent administration of a proton pump inhibitor with low- or very low-dose aspirin (when used for cardioprotection) might block the antiplatelet actions of the aspirin in some patients, at least on a short-term basis. Two studies have shown different results. Thus, in a preliminary study2 of 11 healthy volunteers, treatment with omeprazole reduced the absorption of aspirin and significantly decreased its bioavailability, although the study did not determine whether the desired therapeutic effects of aspirin were prevented. Another study3 of 14 healthy men found that omeprazole did not interfere with the biologic activity of aspirin (at doses of 125 mg) on platelets. I believe that it would be of interest to know additional studies on this subject.

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