it is RU58841 google that and you will get results. Its a topical that blocks all androgen receptors. It works different from Finasteride and Dutasteride as RU does not stop DHT from being produced but rather blocks the receptors that take the DHT, and also blocks testosterone as well as DHT. Some of it (a small amount) likely goes systemic but sides are very rare. Heart related sides are a rare possibility and can potentially be dangerous. It is generally considered to be atleast as effective as finasteride and there are people who have maintained on RU alone for years but its exact effectiveness is unknown cause of so few studies. There have been a very small number of studies (maybe only one) that show it is effective. It costs anywhere from a dollar-3 dollars a day depending on how much you use. It is not established what is the most effective dosing although 40-100mg daily is normal for most people. Pharmacuetical companys stopped looking into the drug presumably because the stuff goes bad unless you leave it in the fridge or use it shortly after it is prepared (which is why people make it at home).
I only recommend RU to people who finasteride or dutasteride doesn't work for, or people who have gotten side effects from that and need to fall back on something (RU is the only thing that can probably stop your hair loss besides oral spironolactone other than finasteride/dutasteride and oral spironolactone gives worse sides than finasteride or dutasteride) I am not one of those people but started it just in case it is needed, as my hair loss is so hyper aggressive I had a pancake sized bald spot very see through by the time I graduated high school. I easily have the most aggressive hair loss of anyone I have ever seen on hair forums