Multiple Selective Responders Should Not be Confounded with Cross-Intolerance to Nsaids

Rationale: Hypersensitivity reactions to NSAIDs can be classified as cross-intolerance where vasoactive mediators are released by nonspecific immunological mechanisms, and selective responders mediated by IgE antibodies or T cells. Those responding to several no chemically-related NSAIDs are considered cross-intolerants. The existence of responders to several NSAIDs with good tolerance to ASA was studied.

Methods: We searched in the dabase of the National Spanish Network for the Study of Adverse Reactions to Drugs and Allergens the possible existence of cases with immediate reactions to different NSAIDs and good tolerance to ASA confirmed by drug provocation tests (DPT). In these the selective response to the culprit NSAIDs was confirmed.

Results: We found 20 cases that acomplished these criteria. The higher number of episodes occurred with a pyrazolone derivative (dipyrone) followed by ibuprofen and other arylpropionic acid derivatives (ketoprofen and naproxen), diclofenac, paracetamol and COX-2 inhibitors. A total of 60 episodes were reported, being 3 NSAIDs involved in 15 cases, and more than 3 drugs in 5 patients.

Conclusions: Subjects with reactions to different NSAIDs but good tolerance to ASA exist. In patients with multiple responses to NSAIDs if tolerance to ASA is not known it should be assessed before being considered as cross-intolerants. This study adds a new phenotype to hypersensitivity reactions to NSAIDs. Further studies are in progress to determine how many cases with NSAIDs hypersensitivity belong to these category.