Finasteride increases anagen hair in men with androgenetic alopecia

Background The growth of scalp hair is a cyclical process of successive pha ses of growth (anagen) and rest (telogen). In previous clinical trials in m en with androgenetic alopecia, treatment with finasteride increased scalp h air counts in a defined area (i.e. increased hair density). Objectives The current study used a phototrichogram methodology to assess t he effect of finasteride on the phases of the hair growth cycle. Patients/Methods Two hundred and twelve men, age 18-40 years, with androgen etic alopecia were randomized to receive finasteride 1 mg daily or placebo for 48 weeks. At baseline and at 24 and 48 weeks, macrophotographs were tak en to measure total and anagen hair count in a 1-cm(2) target area of the s calp. Results At baseline, mean total and anagen hair counts in the finasteride g roup were 200 and 124 hairs, respectively (% anagen = 62%) and the anagen t o telogen ratio was 1.74 (geometric mean). In the placebo group, the respec tive values were 196 and 119 hairs (% anagen = 60%) and 1.57. At week 48, t he finasteride group had a net improvement (mean +/- SE) compared with plac ebo in total and anagen hair counts of 17.3 +/- 2.5 hairs (8.3% +/- 1.4%) a nd 27.0 +/- 2.9 hairs (26% +/- 3.1%), respectively (P < 0.001). Furthermore , treatment with finasteride resulted in a net improvement in the anagen to telogen ratio of 47% (P < 0.001). In this study, treatment with finasterid e 1 mg day(-1) for 48 weeks increased both total and anagen hair counts, an d improved the anagen to telogen ratio. Conclusions These data provide direct evidence that finasteride 1 mg daily promotes the conversion of hairs into the anagen phase. These data support that finasteride treatment results in favourable effects on hair quality th at contribute to the visible improvements in hair growth observed in treate d patients.