Applications of glucocorticosteroids. The effects of twice-daily vs once-every-other-day applications on mouse epidermal cell DNA synthesis.

To determine a schedule for continuous suppression of epidermal cell DNA synthesis, 0.05% fluocinonide ointment was applied either twice daily or once on alternate days to hairless mouse skin for 174 hours. Suppression occurred similarly for both regimens for 78 hours followed by an increase in DNA synthesis despite continued application of fluocinonide. The systemic effect was less marked with the alternate-day schedule. The effect of a single application of the fluocinonide ointment was also studied over 174 hours. Substantial inhibition of DNA synthesis occurred but for a shorter period followed by an increase and then return to normal values. Experiments were performed where second applications were made at various time intervals after the first. These did not appear to affect events until 192 hours had elapsed, when a second application caused profound inhibition of DNA synthesis once more.