Anaphylactic reaction induced by H2-receptor antagonists: Cross reactivity between rantidine and cimetidine

Background: Anaphylactic reactions induced by H2-receptor antagonists are rare. Cross reactivity has been mostly reported between ranitidine and famotidine. To the best of our knowledge, cross reactivity between ranitidine and cimetidine has been reported once.

Methods: We report herein a case of anaphylactic reaction induced by ranitidine with a cross-reactivity to cimetidine.
Results: Case report: A 49-year-old woman with a five year-medical history of asthma, treated by beclometasone and salbutamol, received an intravenous injection of ranitidine in the emergency department because of a gastric acid-re¬lated disorder. Few minutes later, she developed facial flushing, angioedema, dyspnea and itching. Hemodynamic parameters were normal. She recovered immediately after the administration of systemic corticosteroids. Ranitidine-induced anaphylactic reaction was suspected and the patient has received famotidine occasionally without any reaction. Two years later, the patient has been referred to our department of pharmacovigilance. The intradermal tests to ranitidine and cimetidine (1:100) were strongly positive. These tests were performed to a five healthy controls and revealed negative result.
Conclusions: We add to the medical literature a case of ranitidine-induced anaphylaxis with a cross reactivity to cimetidine, but not to famotidine. We point out the usefulness of skin tests in the confirmation of drug imputability and the evaluation of cross reactivity among H2 antagonists.