QUININE AND QUINIDINE PHOTOPRODUCTS CAN BE IDENTICAL

Quinine and its d-isomer quinidine can both cause contact allergy as w ell as photoallergy. Contact allergic cross-reactions between quinine and quinidine are uncommon. In allergic photosensitization the two iso mers cross-react, suggesting the possibility that quinine and quinidin e after UV exposure are converted to one or more common sensitizing ph otoproducts. Solutions of quinine and quinidine at 0.1% in ethanol 99. 5% were exposed to UVA for 14 h (total dose 201.6 J/cm(2)). Using thin -layer chromatography, we identified 8 and 6 photoproducts from irradi ated quinine and quinidine, respectively. Five of these photoproducts were seen in both chromatograms. An identical pattern with four photop roducts was found for both irradiated solutions when these were subjec ted to analysis in a high-performance liquid chromatography system. Th is study indicates that photoproducts from irradiated quinine and quin idine can be identical. This would explain the differences in the cros s-reactivity pattern between contact and photocontact sensitization cl inically.