Led by Dr. A. Sato, a Japanese team of medical researchers published the largest finasteride study ever performed, “Evaluation of efficacy and safety of finasteride 1mg in 3,177 Japanese men with androgenetic alopecia.” It investigated the effects of finasteride over a 3 1/2 year period in men with androgenetic alopecia, or common baldness.

The study found that patients who had experienced hair loss for an extended period of time and were treated with finasteride exhibited notable hair growth. While a fairly small proportion of patients with a hair loss duration over 10 years exhibited “greatly increased” growth, 85% of patients with hair loss duration of more than 15 years experienced “moderate” or “slightly increased” growth. Physicians have thought that people with advanced hair loss do not respond as well as patients in the early stages of hair loss. However, in light of the results of this study, that determination should be reconsidered.

Further, the same study found that the initial age of a hair loss patient at the time of commencing treatment has little to no effect on the outcome. While the efficacy studies that are included in the Propecia package insert were conducted in men 18 to 41 years old, men over 41 appear to respond as well as the younger group. Adverse reactions occurred in only 0.7% of the study population and the Sato study found no increase in adverse safety events over time.

In summary, the Sato study showed an increased response rate to finasteride 1mg with increasing duration of treatment. In addition, it is effective in a larger portion of the male population with androgenetic alopecia than previously thought.

Reference:

Sato A, Takeda A. Evaluation of efficacy and safety of finasteride 1mg in 3,177 Japanese men with androgenetic alopecia. J Dermatol 2012; 39: 27–32.

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