It doesn't matter if you apply finasteride topical or just take the pill, either way it goes systemic. Proof is the protective film on the tablets to prevent even the slightest contact with women who might be pregnant with a male fetus.
the question should be wether the liposomes make a difference or not, which regarding pilos a chemist in the german forum, it doesn't.
Furthermore stop thinking of an overdose. There was a study done with 10mg/day orally taken and even then the side effect profile was as high as in the f*****g placebo group.
Safest option = Orally taken, once daily, 1-1.25 mg depending wheter you wanna safe money or not.
Link to the Study with 10mg/day 18-30y old men for 2 years. :
http://onlinelibrary.wiley.com/doi/10.1002/j.1939-4640.1996.tb01828.x/abstract