[Penetration kinetics of fluocortolone from a new base for ointment and creme (author's transl)]

The penetration of fluocortolone from topically administered Syracort ointment and creme was investigated in guinea pigs. Two fluocortolone standards were tested as reference preparations (ointment and creme). 1. Fluocortolone liberation from the ointments and Syracort Creme within 24 h varied between 55% and 62% of the administered dose. The reference creme gave lower drug liberation values (39%). 2. The penetration profile of fluocortolone changed gradually. Non-absorbed portions and the concentrations in the upper layers of the stratum corneum decreased during inunction up to 24 h. Within the same time concentrations in the deeper layers of the skin increased. 3. The two ointments showed comparably good penetration properties, whereas Syracort creme gave flux values higher than those obtained from the reference creme. 4. 24 h after removal of the non-absorbed portion of the ointments a further persistence of the drug could be observed within the skin: 14.3% to 18.5% after additional 6 days. The mean renal elimination rate was found to be 3 days, a total amount between 28% to 30% of the dose was excreted via urine and feaces. Consequently, fluocortolone can be considered a fast penetrating topical which is accumulated especially in the layers of the epidermis and cutis.