IMMEDIATE RHINOCONJUNCTIVITIS INDUCED BY METAMIZOLE AND METRONIDAZOLE

Objective: To report a case of immediate rhinoconjunctivitis induced b y both metamizole and metronidazole. Methods: Skin-tests (prick and in tradermal) were performed with metamizole, metronidazole, and espyrami cine. Standard PAST was carried out with metamizole and metronidazole. Oral challenge tests were performed single blind with Rhodogil, metro nidazole, espyramicine, metamizole, aspirin, and propyfenazone. Result s: Both skin tests and PAST were negative. We also found that the pati ent tolerated therapeutic doses of espyramicine, aspirin, and propyfen azone. Challenges with Rhodogil, metamizole, and metronidazole elicite d immediate rhinoconjunctivitis. Conclusion: This is an exceptional ca se of immediate rhinoconjunctivitis induced by two unrelated drugs (me tamizole and metronidazole). The pathogenic mechanism implicated in th is process remains unclear. Inhibition of the cyclooxygenase pathway w as excluded and we could not demonstrate the presence of specific IgE antibodies. Nevertheless, an immunologic or idiosyncratic mechanism co uld be responsible.