Influence of tetracycline phototoxicity on the growth of cultured human fibroblasts.

The phototoxic effect of 8 different commercial tetracycline derivatives with long-wave ultraviolet radiation (UVA) on the growth pattern of normal human skin fibroblasts in culture was studied. Chlortetracycline and doxycycline both at a concentration of 50 micrograms/ml and 1.9 J/cm2 of UVA resulted in total cell death with no recovery during a 14-day observation period. Demethylchlortetracycline also showed strong photosensitizing properties with an arrested cell division for 7 days followed by a recurrence of cell growth. The other tetracyclines tested under identical conditions had only weak or no phototoxic influence on cell growth. These experimental data correlate very well with clinical reports and comparative phototoxicity trials in humans. This experimental method may thus be of value for predicting tetracycline phototoxicity in humans.