The aspirin-ibuprofen interaction in rheumatoid arthritis

1 This was a double-blind crossover trial of ibuprofen and soluble aspirin against each drug alone and against placebo in patients with rheumatoid arthritis. Two dosage regimes were tested. 2 A weak clinical additive effect was demonstrated between soluble aspirin and ibuprofen in patients with rheumatoid arthritis using moderate (1600 mg ibuprofen and 3.6 g aspirin daily) but not low (800 mg ibuprofen and 2.4 g aspirin daily) dosages of both drugs. 3 A significant correlation between clinical efficacy and serum ibuprofen but not salicylate level was found in the single drug periods of the trial. 4 No consistent effect of ibuprofen administration on serum salicylate levels was found. 5 Concurrent salicylate administration produced significant lowering of serum ibuprofen levels without affecting elimination half-lives of the drug.