Using the macaque model of androgenetic alopecia, we examined the effects of RU58841 on hair growth in the frontal bald scalp, and the rate of follicular cyclic growth was analyzed by micromorphometry (folliculogram) in biopsied skin. Solutions of RU58841, 5, 3, 1, and 0.5%, and vehicle (propylene glycol, isopropranol, isopropyl myristate, water, 50:30:2;18%) were applied topically, once per day, in 4 to 5 monkeys in each group for 6 months. Three monkeys in the 5%, 0.5% and vehicle groups were continuously treated for 12 to 24 months in order to examine long-term effects. Our observations revealed a marked increase in density, thickening, and length of hair in all four cases of the 5% group as early as 3 months after treatment. At the fifth month, the analysis of folliculogram showed an average two- to threefold increase in the population of follicles enlarged to terminal size and of anagen phase compared to that of 0 time. However, 3% solution induced a moderate effect in only one case and the remaining four cases showed very minimal effects in both gross observation and folliculogram analysis. The effects with 1 and 0.5% were much weaker. For long-term studies, all cases in the 5% group showed progressive hair and follicular growth which occurred continuously from 3 to 7 months, and thereafter these regrown hairs were maintained as long as application continued. In all cases, postwithdrawal hair loss appeared after 3 months. The long-term effects in the 0.5% group showed no further progression from the initial minimal effects. No placebo effects were noticed in either short or long term application. Providing a sufficient dose, 5% in these studies, of topical RU58841 induced remarkable effects on hair and follicular regrowth in the initial stage and these effects were maintained by continuous treatment.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.