The effects of topical diazoxide on hair follicular growth and physiology of the stumptailed macaque.

Diazoxide, an anti-hypertensive agent, has diverse pharmacologic effects; hypertrichosis, hyperglycemia associated with suppression of insulin release, and elevation of serum levels of androgens. Taking advantage of the hypertrichotic side effects of diazoxide, we examined the effect of topical application of the drug on hair regrowth in the bald frontal scalp of stumptailed macaques (Macaca arctoides); we also monitored systemic side effects. Using 7 adult stumptails, we applied diazoxide (5% solution in a vehicle) topically on the bald frontal scalp, once a day, 5 days per week. Two of seven macaques had vehicle alone applied. Hair growth was monitored by photographic recording (once every month) and by sequential analysis of folliculograms from biopsied skin (once every 4 months). We also examined body weight, hematology, blood pressure, heart rate, serum levels of testosterone and dihydrotestosterone, and glucose tolerance for a 4-month period. All 5 diazoxide-treated animals showed thickening and maintenance of the frontal hair during the entire treatment period (16 months). Analysis of folliculograms showed progressive enlargement of hair follicular size and acceleration of its cyclic growth from telogen to anagen phase and prolongation of anagen phase in all treated animals. Controls showed no consistent progressive changes of follicular growth. None of the animals treated with diazoxide showed abnormal changes in physical growth, cardiovascular function, serum levels of androgens, glucose tolerance (including insulin levels), or hematology.