Well the treatment of topical finasteride is available overseas. I believe there's one such treatment called Lipoxidil, and uses lipsomes and zinc(?). The effectiveness is probably related to the carriers. There just isn't enough research in the area of topical finasteride and hairloss, and several variables to consider.
I remember reading one sole study that stated serum DHT dropped 40% on a .05 topical solution, but with no additional hair growth. Then a few years later these findings were contradicted as far as serum DHT. There's another much more recent 2007 study from Mazandaran University in Iran that found similar therapeutic effects between topical (.1%?) and oral ingestion. Who knows?
And I really shouldn't say side-effects were negligible. After jogging my memory a bit (it's been a while) I was no longer getting spontaneous morning erections after using minoxidil/topical finasteride 1x a day. I had actually stopped oral finasteride for several months due to sides, and then started topical finasteride on a whim. I noticed my rate of hairloss diminished greatly after only two applications, especially at the crown. Of course, there isn't any way to determine where there was any new hair growth due to topical finasteride. For what it's worth, there wasn't nearly as a much a problem of maintaining an erection, as compared even to an oral dose of .25mg though.
I still think it's worth giving a shot, for someone who has a few pills available and is suffering from sides. Part of the Merck patent talks about the lowest possible topical dosage while still maintaining efficacy. I guess there's always nizoral, spironolactone, green tea and grape seed extract, bayberry too as yet even more options. I don't think we're as limited as most people believe. I always say you don't know until you at least try, as not everyone balds for the identical reason, or in the same manner.
For me, I think I'm likely done with finasteride in general though. In my particular case of alopecia, I've since discovered methods that work better with no sexual sides. Again, take it for what it's worth.