I've mixed pharmaceutical spiro tabs into the dermovan at approx. 15%!!!!
In my experience, It DID NOT work at all? The commercially available 5% spiro seemed to have a much stopped thr receding hairling to a MUCH higher degree. I'm stumped????
Maybe it was a formulation issue. I added all the spiro and mixed it over a weeks time. The only explanation I can think of is that it was not a homogeneous mixture???
Good luck to fellow bros....I hope you get better results than me with my chemistry background.