Well phase 3 can take way too long , you need to gather alot of people who are 1) balding 2)willing to visit the building where the study is being carried out every X days for as long as the study is going to take , 3) live relatively close to these buildings 4) fulfill criteria like not taking extra medication , not being in a high risk group , being aged from X to Y years old .
After that you have to conduct the study and finally gather the results , and make them into a scientific paper , which can take up to a year .
Phase 3 study has ended like 2 months ago if i remember correctly , now they are gathering and evaluating the results .
As for the topical finasteride issue , merck had a patent for topical finasteride afaik , but never made it into a product .
I barely know anything about patent laws , but i guess p3074 is a new patent consisting of topical finasteride and their vehicle of hydropropyl chitosan , so i dont know if it could speed up the fda testing process by being topical form of an approved drug, or not
However the fact that they did 3 full phase studies implies the latter