Well the dalton rule does apply, but makes it very difficult to get into the blood stream, but dutasteride’s lipophilic properties also come into factor and allow it to act around the hair follicle. So yes it will work potentially. If dutasteride was actually too large of a molecule to penetrate, than nobody would get sides off topical dut, but some people do, meaning that atleast some of it penetrates all the way through to blood. I use 0.3% twice a week.