Variations in percutaneous absorption of testosterone in the rhesus monkey due to anatomic site of application and frequency of application.

This study determines if the anatomic region affected percutaneous absorption in the rhesus monkey, an animal model with some relevance to man. Percutaneous absorption of testosterone (13.3 microgram/cm2) from the ventral forearm was 8.8 +/- 2.5%. Absorption from the chest was slightly less (5.3 +/- 0.6%) while that from the cheek was about the same (9.6 +/- 0.2%). Absorption from the scalp was greatly increased (20.4 +/- 2.7%), that from the vagina was the greatest (63.1 +/- 2.6%). As previously noted in man, anatomic variation in skin absorption exists in the rhesus. The ratio of scalp absorption to ventral forearm absorption in the rhesus was similar to that in man. The next objective was to determine the percutaneous absorption of testosterone when applied as a single dose or on a repetitive basis. There was no substantial difference in total absorption when 13.3 microgram/cm2 was applied as a single dose or when the 13.3 microgram/cm2 was applied three times, totaling 40 microgram/cm2. However, when 40 microgram/cm2 was applied as a single dose, absorption was substantially increased over 13.3 microgram/cm2 applied either once or three times. These results confirm previously reported results done with single versus repetitive doses of hydrocortisone.