MINOXIDIL SULFATION IN THE HAIR FOLLICLE

The in vivo model which may be the most accurate for the ability to pr edict hair growth in humans, and which was utilized in the preclinical development of minoxidil, is the adult stumptailed macaque. Previous reports have suggested that the enzyme activity which accounts for the activation of minoxidil, i.e., minoxidil sulfotransferase, is present in skin. We have demonstrated that scalp skin from the stumptailed ma caque contains minoxidil sulfotransferase activity, and further with d issection of that scalp skin into epidermis, dermis and hair follicle, most of sulfotransferase activity was present in the follicle. Sulfot ransferase activity in the hair follicle in freeze-dried scalp skin se ctions from 9 stumptailed macaques ranged from 47 to 84% of the total (mean 61 +/- 12%). Much less minoxidil sulfotransferase activity was m easured in the epidermis (mean 18 +/- 11%, with a range of 2-37%) and the dermis (mean 21 +/- 8%, with a range of 4-35%) of these scalp sect ions. These results indicate that the scalp skin from the stumptailed macaque contains minoxidil sulfotransferase activity and this activity is largely localized in the hair follicle which may account for its a bility to stimulate hair growth in this animal model.