Topical hair loss treatments: what is the difference between RU58841 and CB-03-01?

RU58841 is an androgen receptor blocker that was first discovered in the early 1990s, and it has been extensively studied in animal models. When applied topically, it is highly effective in stopping the progression of balding and can even stimulate some hair re-growth. No systemic side effects have been found in monkeys treated topically with RU58841. However, due to issues unrelated to RU58841 itself, it has never gone through the formal human testing processes to allow it to be approved by the FDA and other regulatory agencies for marketing as a balding treatment. It is available for purchase as a research chemical, and many individuals have been using it to treat balding over the last few decades. It is reported to be very effective in stopping hair loss with minimal side effects. A few individuals report that it stimulates hair re-growth as well.

CB-03-01 is an androgen receptor blocker first discovered in the 2000s. Initial studies in animal models found it could block androgen receptors when applied topically but not when given systemically. Its lack of activity when applied systemically means it exhibited no systemic anti-androgenic side effects in rats injected with the drug. Its ability to block topical androgen activity was described by the early researchers as being about three times more potent than flutamide. The fact that it has no anti-androgenic activity when applied systemically is probably due to the fact that after it enters the body it is almost immediately metabolized into an inactive form.