Long-term tolerability of nimesulide and acetaminophen in nonsteroidal antiinflammatory drug-intolerant patients

Background: Oral challenges are used to identify alternative nonsteroidal antiinflammatory drugs (NSAIDs) for patients who react adversely to drugs of this class, but challenge conditions often differ from those in which the drug will actually be used. Objective: To determine whether the results of oral challenges with nimesulide or acetaminophen, using cumulative administration of a single therapeutic dose while the patient is in good health, can predict the response to multiple doses of the drug during future illness. Methods: Follow-up interviews were conducted with 248 NSAID-intolerant subjects who had tolerated oral challenges with nimesulide and/or acetaminophen 1 to 3 years earlier. We analyzed the adverse reaction rate in light of the febrile/nonfebrile nature of the condition treated and the number of doses consumed. Results: Nimesulide was tolerated by 115/122 (94.2%) of the patients who had tried it; acetaminophen by 71/75 (94.6%). A total of 8/159 (5%) patients had experienced reactions (seven urticarial and one asthmatic) to one or both drugs. Intolerance was unrelated to the nature of the condition treated or the number of doses administered, but all four patients who failed to tolerate acetaminophen and 3/7 of those who reacted to nimesulide had histories of chronic urticaria. Conclusions: Oral challenges can reliably predict long-term NSAID tolerability in patients with previous adverse reactions to other drugs of this class, except for patients with chronic urticaria.