The action spectrum in quinine photosensitivity

The action spectrum for 24-h ultraviolet erythema was determined in three elderly patients who presented with a photosensitive eruption and who were taking quinine sulphate for night cramps. In each case the in vivo action spectrum was consistent with the absorption spectrum of quinine, and extended from about 370 nm to at least the lower wavelength limit of terrestrial sunlight (approximately 300 nm). Calculations based upon the combination of the action spectrum for quinine photosensitivity, the spectrum of terrestrial sunlight, and the transmission properties of various topical sunscreens, indicated that a broad absorption spectrum sunscreen would be required to provide adequate photoprotection.