Anaphylactoid reactions due to nonsteroidal antiinflammatory drugs: clinical and cross-reactivity studies.

Background: Anaphylactoid reactions due to nonsteroidal antiinflammatory drugs have been described.

Objective: To study the clinical characteristics of 21 patients with anaphylactoid reactions due to nonsteroidal antiinflammatory drugs and to determine the cross-reactivity to non-steroidal antiinflammatory drugs not involved in the previous reactions nor structurally related by means of single-blind, placebo-controlled drug challenges.

Patients And Methods: Twenty-one patients who exhibited clinical evidence of anaphylactoid reactions after nonsteroidal antiinflammatory drugs were recruited for the study at the time of admission in Emergency Unit of our Hospital, Single-blind, placebo controlled oral challenges with nonsteroidal antiinflammatory drugs (except those reported by the patient as being responsible for the previous reaction), were performed in all patients.

Results: Fifteen patients were woman and six man, with a mean age of 35.7 years (range 18 to 62 years). Thirteen patients (60%) were normal subjects without concomitant diseases. No increase in frequency of atopy in comparison to the general population was observed. Pyrazole derivatives were the most common nonsteroidal antiinflammatory drugs involved (71.3%). A tolerance to drugs included in drug challenge protocol was noted in all patients.

Conclusion: In our population, pyrazole derivatives were the most common nonsteroidal antiinflammatory drugs involved in anaphylactoid reactions. Most patients appeared to be otherwise normal subjects without concomitant disease and no cross-reactivity with other non-steroidal antiinflammatory drugs not involved in the anaphylactoid reaction nor structurally related was found.