Long-term follow-up of men with male pattern baldness treated with topical minoxidil

Forty-one men with male pattern baldness completed 132 study weeks (2 years 9 months) with topical minoxidil and had follow-up 1-inch target-area vertex scalp hair counts. Initially these men were treated with either twice-daily 2% topical minoxidil for 12 months or 3% topical minoxidil for 8 to 12 months (one third of the subjects received placebo for the first 4 months). After 12 months all subjects continued to apply 3% topical minoxidil twice daily for 1 more year, after which they were randomized to once- versus twice-daily topical minoxidil for an additional 9 months. Those subjects who changed to once-daily application of topical minoxidil at 2 years had a mean change from baseline nonvellus hair count at 1 year of 291.2 (range of hairs four to 553) and at 2 years 9 months of 235 (two to 592 hairs). Those subjects who continued with twice-daily application of topical minoxidil throughout the study had a mean change from baseline nonvellus hair count at 1 year of 323 (15 to 589 hairs) and 335 (13 to 808 hairs) at 2 years 9 months with maintenance topical minoxidil. There were subjects on both maintenance schedules of topical minoxidil who lost some of the nonvellus hair they had initially gained with topical minoxidil; however, there was a greater mean loss in those patients following the once-daily versus twice-daily topical minoxidil regimen (p = 0.05). No subject lost nonvellus target hair as compared with baseline. Subject and investigator assessments of hair growth as compared with baseline diminished during the maintenance course of treatment with topical minoxidil; this was not related to the frequency of topical minoxidil application. However, by the completion of the 2-year 9-month period, the investigator felt that 82.9% of subjects still had minimal regrowth and 4.9% had moderate regrowth over baseline; subjects consistently graded their hair growth as greater than did the investigator. Side effects were minimal and well tolerated. These results indicate that continued use of topical minoxidil sustains the majority of vertex nonvellus hair growth initiated during the first 12-month period of topical minoxidil use and that twice-daily application of topical minoxidil is preferable to once-daily application for maintenance therapy.