The Interaction of Topically Applied 2% Erythromycin, 4% Erythromycin and Tetracycline with Narrow Band UVB

Objective: Various topical agents block UVB penetration when applied before UVB therapy. The effects of topically used erythromycin and tetracycline on narrow band UVB has not been considered yet. We investigated the effects of topically used erythromycin 2%, erythromycin 4% and tetracycline on the penetration amount of narrow band UVB. Methods: In this study 32 patients without any photodermatose were included. We determined MED values with phototest. We investigated the effects of thin (0.1 cc/25 cm2) and thick (0.3 cc/25 cm2) layers of erythromycin 2%, erythromycin 4% gel forms and tetracycline ointment on MEDs. Results: In this study comparing MEDs of narrow band UVB alone and with topical application of each agent, it was determined that MED values of thin and thick layers tetracycline were statistically significant (p<0.005). However we found that there was no significant change in MEDs of topical erythromycin 2% and erythromycin 4%, both in thin and thick layers (p>0.005). Conclusion: Thin and thick layers of topical erythromycin 2% and 4% could not change MEDs significantly, whereas thin and thick layers of tetracycline increased MEDs significantly decreasing the effect of the narrow band UVB.