Background In the clinical practice patients with a history of acute urticaria induced by a single non-steroidal anti-inflammatory drug (NSAID) and seeking for safe alternative drugs generally undergo tolerance tests with alternative NSAIDs that have little or no cyclooxygenase-1 (COX-1) enzyme inhibitory activity. This practice does not allow for the detection of single NSAID reactors and may lead to unnecessary avoidance of many potentially useful NSAIDs.
Objective Evaluate aspirin challenge as a means to distinguish single from multiple NSAID intolerance in patients with a clinical history of acute urticaria induced by a single NSAID.
Methods One hundred and seventeen otherwise normal subjects with a history of acute urticaria following the ingestion of a single NSAID (pyrazolones (n=58), nimesulide (n=17), propionic acid derivatives (n=13), aryl acetic acid derivatives (n=14), acetaminophen (n=9), piroxicam (n=5), and indometacin (n=1)) underwent single-blind placebo-controlled oral challenges with aspirin. Aspirin-intolerant subjects underwent further tolerance tests drugs exerting little or no inhibitory activity on COX-1 enzyme (including paracetamol, nimesulide, rofecoxib, tramadol, and floctafenine).
Results Aspirin induced urticaria in 28/117 (24%) patients. Five out of 28 (18%) aspirin reactors did not tolerate alternative NSAID on subsequent oral challenges.
Conclusion In subjects with a history of urticaria induced by a single NSAID (other than aspirin) the diagnostic workup should start with an aspirin challenge in order to detect single/multiple NSAID reactors.