Typ-I-Sensibilisierung gegenüber Ranitidin

Ranitidine is an H 2 -receptor antagonist which is generally well tolerated. Since the 1970s, it is used for the treatment of peptic ulcers, esophageal reflux, and Zollinger-Ellison syndrome. In dermatology, ranitidine is recommended as a second-line therapy for chronic urticaria that is not responsive to anti-H 1 monotherapy. We report the case of a 45-year-old woman who presented with urticaria, facial edema and dyspnea after simultaneous ingestion of Sostril (ranitidine) tablets and diclofenac. Scratch testing with Sostril (ranitidine) resulted in a strongly positive reaction in this patient whereas the same test remained negative in a control patient. The scratch test as well as an oral challenge with diclofenac were negative. Because of anaphylactic risk, ranitidine was not tested by oral challenge. A basophil degranulation test was carried out with the suspected drug Sostril, with pure ranitidine, and separately with each constituent of Sostril tablets (microcristalline cellulose, magnesium stearate, hypomellose, titane dioxyd and triacetine) in different concentrations. Significant basophil activation was detected only in aliquots with Sostril or with pure ranitidine, whereas stimulation with the different nonactive constituents produced no basophil degranulation. The results of cutaneous scratch test and in vitro basophil degranulation test suggest immediate-type hypersensitivity to ranitidine to be responsible for the anaphylactic reaction in this patient. Diclofenac may have amplified this reaction by nonimmunologic pathways. Considering the extensive use of H 2 -receptor antagonists, real type I hypersensitivities to these molecules remain exceptional with only few well-documented cases in literature.