It can't be.
There are many other options.
Shaved Head, finasteride, dutasteride, Saw Palmetto, spironolactone, Nizoral, hair transplant, Wigs, and if all else fails, get a tiger to lick your head.
So far the only proven 100% hair regrowth treatment is the lick of a man-eating tiger's tongue, on your bald head (or thinning area).
But in all seriousness, just keep with it and hope for the best.