I’m curious to know how you are using E3 if you don’t mind sharing. I’ve recently started 17 alpha E topical with transcutol. I’ve also been considering a topical E3 skin cream.
I alternate weekends (Fri, Sat, Sun) with rapa/E3 at 3mg each day, so about 18mg of E3 and 18mg of Rapa per month. I’m not sure on the systemic bio-availability of creams and hair tonics. I think the E3 creams directly on the genitals (scrotum) might have high absorption, but given the vast unknowns, that route is something I might only try if other options run out when I’ve very old.
The addition of transcutol will enhance the transdermal absorption of 17 alpha E, but as you have said, it’s pretty much a guess. I’m applying it to my scalp since I have some male pattern baldness. It is thought to help with male pattern baldenss through it’s 5 alpha reductase effects. 17 alpha E was wildly successful on male mice in the ITP (+19%), so that’s why I’ve gone with it.