1470 Clinical characteristics of ranitidine induced hypersensitivity

Tuesday, 7 December 2010

Purpose: Ranitidine is a widely used drug for gastrointestinal problem and is usually associated with a low incidence of adverse reactions. There have been only a few cases of immediate type hypersensitivity reactions to ranitidine. To see the characteristics of ranitidine induced hypersensitivity, we analyzed 10 cases of ranitidine induced hypersensitive reaction

Methods: Patient who is suspicious of ranitidine induced hypersensitivity was evaluated. Skin test and oral provocation were performed. We also evaluated the cross reactivity of other drugs (cimetidine, famotidine and proton pump inhibitor) used for gastric protection.

Results: Eighty percent of patient was positive in ranitidine skin test and oral provocation test. Mean age of these patients was 35 7 years old. Male: female ratio was 4:6. Two cases illustrates a severe anaphylactic reaction after a single intravenous dose of 50 mgs of ranitidine and three cases showed anaphylactic reaction after oral intake of dose of 150mg of ranitidine. Five cases illustrated only skin eruption after oral intake of 150mg of ranitidine.  All of five cases who illustrated anaphylactic reaction showed positive reaction with skin prick test and/or intradermal skin tests. Three patients who showed only skin reactions were positive in intradermal skin test with ranitidine.  Two of cases were negative for skin test with ranitidine and they showed mild skin eruption with itching sense in 2 hours and 3 hours each with 75mg of ranitidine of oral provocation test.  All of the 10 cases showed negative reaction in skin test and oral provocation test with cimetidine, famotidine and proton pump inhibitor.

Conclusion: Our case suggests that ranitidine may induce immunoglobulin E-mediated anaphylaxis but also non-immunological mechanisms may be involved in hypersensitivity reactions.

Ranitidine may have very rare cross-reactivity with other gastric protective drugs. Clinicians should therefore be aware of possible life-threatening adverse reactions to commonly used H2-receptor antagonists such as ranitidine.