Quinine and quinidine cross-react after systemic photosensitization in the mouse

Using a protocol for induction of photoallergy in the mouse after systemic administration, quinine was shown to be just as potent a photosensitizer as its d-isomer, quinidine. The dose-response curves for the two isomers followed a similar course both for induction and elicitation. Cross-reaction experiments, where induction and challenge were performed with different isomers, indicated that quinine and quinidine cross-react. Traces of the isomer as a contaminant in the test compound are not likely to account for this cross-reactivity. For practical purposes, photosensitization to one of these two quinoline methanol isomers seems to exclude the future use of the other.