Outcome of long-term treatment with the 5 alpha-reductase inhibitor finasteride in idiopathic hirsutism: clinical and hormonal effects during a 1-year course of therapy and 1-year follow-up

OBJECTIVE: To evaluate the long-term efficacy of the 5 alpha-reductase inhibitor finasteride in idiopathic hirsutism. DESIGN: Prospective clinical study. SETTING: Outpatients in a university hospital. PATIENT(S): Fourteen young women with idiopathic hirsutism. INTERVENTION(S): Finasteride, 5 mg once daily, was given for 12 months. MAIN OUTCOME MEASURE(S): Degree of hirsutism, graded by a modified Ferriman and Gallwey score, serum sex hormones, and serum and urinary markers of 5 alpha-reductase activity. Clinical outcome was evaluated up to and including the 1-year post-treatment period. RESULT(S): The Ferriman and Gallwey score showed a remarkable reduction after 12 months of finasteride treatment (4.4 +/- 0.7 versus 11.8 +/- 1.0; mean +/- SEM). Serum levels of the two 5 alpha-reductase activity markers, dihydrotestosterone and 3 alpha-androstanediol glucuronide, decreased, and urinary C19 and C21 5 beta:5 alpha steroid metabolite ratios consistently increased during finasteride administration. These changes were reversed readily after cessation of treatment. No significant adverse effect was reported. Nine of 14 women completed the 1-year post-treatment follow-up. Their hirsutism scores were increased substantially as compared with values recorded at the end of therapy, but still were lower than baseline values. CONCLUSION(S): The 5 alpha-reductase inhibitor finasteride is effective and well tolerated in longterm treatment of women with idiopathic hirsutism. Post-treatment follow-up suggests that drug effects on hair growth are sustained in the majority of subjects with this disorder.