Different risks for NSAID-induced anaphylaxis.

Background: After drugs are marketed, spontaneous reporting systems can provide valuable information regarding the occurrence of suspected adverse drug reactions. The Netherlands Pharmacovigilance Foundation has received a substantial number of anaphylactic reaction reports related to the use of nonsteroidal antiinflammatory drugs (NSAIDs).

Objective: To investigate whether the risk of anaphylactic reactions being reported during the use of various NSAIDs is greater than with other classes of drugs and if differences among NSAIDs exist.

Methods: In a case/noncase design, reporting odds ratios (RORs) were calculated using logistic regression analysis. Cases were defined as reports in which anaphylactic or anaphylactoid reactions were reported; all other reports were considered as noncases. The index group consisted of reports in which NSAIDs were mentioned as the suspected medication; the reference group consisted of all other reports.

Results: Between January 1985 and November 2000, the Netherlands Pharmacovigilance Foundation Lareb received 76 cases concerning anaphylactic reactions to NSAIDs. These drugs are strongly associated with anaphylactic reactions. The ROR adjusted for age, gender, and source of the reports was 9.4 (95% CI 6.9 to 12.7). Anaphylactic reactions associated with the use of naproxen, ibuprofen, and diclofenac were reported disproportionately with respect to other drugs. The corresponding RORs from logistic regression analysis adjusted for age, gender, and reporting source for diclofenac, naproxen, and ibuprofen were 17.2 (95% CI 12.1 to 24.5), 9.1 (95% CI 5.2 to 15.9), and 5.5 (95% CI 2.5 to 11.9), respectively.

Conclusions: The results of this study strengthen previous findings concerning the relative high risk of developing an anaphylactic reaction during the use of NSAIDs, particularly diclofenac, ibuprofen, and naproxen.