Influence of Admixture with Urea Ointment and White Petrolatum on the Penetration of Corticosteroids into Yucatan Micropig Skin

Abstract

Admixtures of two primary corticosteroid ointments, Almeta® and Myser® ointments, were made with urea ointment and white petrolatum. The release rate of corticosteroids from the admixed ointments with urea ointment and white petrolatum to a buffer solution were significantly lower than those expected from a dilution ratio 0.5 for both Almeta® and Myser® ointments. Also, for the admixtures with urea ointment, the amount of corticosteroids penetrating into the model skin was larger than that expected from the dilution ratio, especially for Myser® ointment, while the amounts of corticosteroids penetrating into the skin from the admixtures with white petrolatum were smaller than those expected from the dilution ratio, for both primary ointments.An electron probe micro analyzer was used to observe the actual distribution profile of corticosteroid molecules in a cross section of the skin. In the case of the Myser®-urea ointment admixture, the distribution profile of difulprednate was quite homogeneous, probably due to the softening effect of urea on the skin and the affinity of difulprednate with skin tissue, though the urea ointment did not have much effect on the distribution profile of alclometasone released from the Almeta® ointment. On the other hand, difulprednate was concentrated at the surface for the admixture with white petrolatum.