The market for such a product is tremendous, consequently, if there is money to be made in it you can be sure there are drug companies working on it to produce a pill. It is bigger than the VIAGRA market and patients will spend all they have to keep from losing their hair.
One big problem is the fact most of this problem is genetic. The other causes include diseases that involve hormone problems. There are so many different causes that the possibility of a single treatment is remote. Drug companies will only look for solutions that involve the chronic use of some medication in order to get the repeat business. A machine is expected too work fast and last long or the expense of treatment is great.
When it comes to stopping hair growth the same criteria must be met...fast results and long lasting results. That is what happened to Vaniqa. It was long lasting but the cost and inconveience of daily use made it impossible for patients to continue using it.
My personal doctor is the one who invented Vaniqa and he has another product that will make hair grow but the same problems are present. It requires continuous use and multiple applications per day plus it is prohibitively expensive. It just is not worth it for patients.