Indomethacin is a potent inhibitor of prostaglandins biosysnthesis. Sunburn erythema is mainly mediated by prostaglandins.

Our purpose was to compare objectively the effectiveness of topical indomethacin with topical corticosteroid on the suppression of UVB erythema

Sixteen male medical students who had not exposed their back skin during the last year were included in this study. According to the individual´s MED, 1,2, and 3 MED of UVB were irradiated on each back in triplicate lines. Immediately after UVB irradiation, 2.5% indomethacin solution and 0.25% desoximethasone were applied to each row with one row left for control. 24 hours after the initial application the intensity of each erythema was measured by the naked eye and by colorimeter.

The suppressive effectiveness of 2.5% indomethacin solution on UVB induced erythema was superior to that of 0.25% desoximethasone. The L* and a* value of colorimeter were significantly correlated to the differencies of UVB induced erythema among the experimental and control groups is a useful and rapid method to evaluate the UVB induced erythema, and can give a numerical expression to eye perception.

Our data confirm that topical indomethacin has a stronger suggestive effect on UVB erythema than that of topical corticosteroid.. We suggest that the suppressive effect of indomethacin is mainly due to the inhibition of prostaglandins biosynthesis. The colorimeter CR-200(MINOLTA) is well correlated with the naked eye score and is a useful instrument for objective measurement of the degree of erythema.