Failure of zafirlukast to prevent ibuprofen-induced anaphylaxis

Background: Anaphylaxis to nonsteroidal anti-inflammatory drugs is thought to depend on cycloxygenase inhibition coupled to upregulation of 5-lipoxygenase-dependent pathways. The introduction of leukotriene-receptor antagonists afforded the opportunity to test this hypothesis. These agents provide at least partial protection against aspirin-induced anaphylaxis during controlled challenges but we did not know whether the level of protection was high enough to block symptoms from ingestion of a full dose of aspirin. Methods: We report a patient with moderately severe asthma who experienced an episode of anaphylaxis following ingestion of 400 mg of ibuprofen while under therapy with 20 mg of zafirlukast given twice a day. Results: No further episodes of anaphylaxis have been noted following institution of complete avoidance to all nonsteroidal anti-inflammatory drugs. Conclusions: Patients who are sensitive to cycloxygenase inhibitors should practice complete avoidance of these drugs even while under therapy with leukotriene modifiers.