Frequency of application on percutaneous absorption of hydrocortisone.

This study determines the percutaneous absorption of hydrocortisone when applied as a single dose or on a repetitive basis. Application was to the shaved ventral forearm of the rhesus monkey, an animal model in which some relevance to man has been shown. Absorption was quantified by measuring 14C in aliquots of urine over five days. There was no substantial difference in total absorption when 13.3 microng/sq cm was applied as a single dose or when the 13.3 microng/sq cm was applied three times, totaling 40 microng/sq cm. However, when 40 microng/sq cm was applied as a single dose, absorption was substantially increased over 13.3 microng/sq cm applied either once or three times. Additionally, when the skin was washed between applications to remove previously applied material in the three application experiment, there was a statistically significant increase over not washing the skin. The clinical importance of these results to man will await appropriate clinical studies.