Available since the 80s , from 2% to 30 % , many people have being using it with great success. Minoxidil must be convert it into minoxidil sulphate ( in your body ) to work. It depend how much of this enzyme you have, the best results you can get.

usually use it in conjunction with minoxidil, tretinoin increase the enzyme that convert minoxidil into active minoxidil in your skin. Usually it at 0.025 % .

Available as oral since the 90s and early 2000s, it have being use it lately as topical in a hope to reduce side effects.