Tolerance to acetylsalicylic acid (ASA) induced in ASA-sensitive asthmatics does not depend on initial adverse reaction.

A state of tolerance to aspirin (ASA) was induced in 10 aspirin-sensitive patients by daily administration of incremental doses of ASA. No adverse reactions were reported. The initial dose (from 5 to 60 mg) was gradually increased each day up to 300 mg and then doubled. 50 mg indomethacin given the day after administration of 600 mg ASA did not elicit any symptom of intolerance. The authors discuss a possible mechanism of tolerance to aspirin in ASA-sensitive asthmatics after ASA administration, suggesting that it might be connected either with inhibition of the lipooxygenetic pathway of arachidonic acid metabolism or with blockade of the cyclooxygenase supplementary binding site by salicylic acid, a product of acetylsalicylic acid hydrolysis. This would prevent aspirin from binding with the catalytic cyclooxygenase site.