Inhibition of ultraviolet and phototoxic dermatitis in the mouse.

The effect of inhibitors on the inflammatory oedema elicited by medium-wave ultraviolet radiation (UVB) and long-wave ultraviolet radiation (UVA) in combination with chlorpromazine has been studied in the mouse, by means of a quantitative technique. Inhibition of the UVB reaction was observed with indomethacin, acetylsalicylic acid and betamethasone valerate, whereas the latter compound only was effective in the phototoxic state. No inhibition was obtained with hydrocortisone, phenylbutazone, epsilon-aminocaproic acid, polyphloretin phosphate, clemastin, alpha-tocopherol or ascorbic acid. With indomethacin and betamethasone valerate there was no inhibition at high doses when the compound was administered before UVB irradiation. These results are in accordance with a proposed central role for the prostaglandins in UVB inflammation. It is suggested that the phototoxic reaction to chlorpromazine may not be due to mediator action but rather to the effect of toxic photoproducts.