I have just found this paper from Sherman Frankel of U of Pennsilvania. He used the Freedom of Information Act to examine the FDA files on Propecia. The conclusions he draws from looking at the data sent to the FDA from Merck is that 0.2mg of Propecia is almost as effective as either a 1mg or 5mg daily dose. He also concludes that the potential side effects (loss of libido) may be reduced on a significantly lower dose. The study can be found at:
I have known that a dose of 0.5mg is almost as effective as 1mg finasteride for hair loss. What I knew prior to reading the above reference came from verbal conversations with Dr. David Whiting (https://www.hairlosstalk.com/newsletter/article75.htm), a world expert on Propecia.
The article you reference is valuable for the few patients I have seen who can not tolerate the drug — those that may be better off with a smaller dose than no medication at all. I will ask Merck to comment on this for me and report it back to my readership. Thank you for bringing this to my attention.