Finasteride (Propecia/Proscar) inhibits the enzyme 5alpha-reductase which basically converts some AAS to DHT, (DHT "speeds up" hair loss). Not all AAS are DHT derivatives, (broken down into DHT) therefore this only applies to the AAS which are metabolized to DHT and more specifically, those which are metabolized to DHT via the 5alpha-reductase enzyme.
To sum it up, Finasteride (Propecia/Proscar) will only slow the side effects of Testosterone and its derivatives Methyltestosterone and Halotestin. It shows no effect on those AAS unaffected by reductase, (Anadrol, Anavar, D-bol, Tren, Primobolan, Winstrol) and can actually "enhance" unwanted side effects if taken with Nandrolone and some of its derivatives!
STEEDA~