That 500 dalton bullshit is a meme at this point. Everyone here is obsessed with "penetration", what they really should be obsessed with is scalp retention.
Well it's not.
Topical Finasteride reduced my serum DHT by 60% at 0.1%
Topical Duasteride reduced my serum DHT by 20% at 1%
I used a dose 10 times larger on a med with a half life of 5 weeks, not hours.
Explain that to me.