Well I can speak for myself with Setipiprant. At ~300mg a day since around thanksgiving, it has not been able to stop my hair from falling out. But whether or not its been slowing it down or I have been seeing reduced shedding is much harder to tell. For that reason, I will likely continue to the treatment until I find a better replacement.
Keep in mind, that this drug is being trialled at 1000mg/day where is significantly more than my 300mg/day. We have to wait for phase 2 results to be released but many of the more educated members here don't think it will work from a scientific POV.