Oral Minoxidil appears to work substantially better in patients with low SULT1A1 enzyme activity

For anyone who wants to read the whole thing:

https://onlinelibrary.wiley.com/doi/10.1111/jocd.16473

Tldr: follicles with low SULT1A1 activity are much better at importing the Minoxidil Sulfate which has already been converted by SULT1A1 and 2A1 in the liver, people who respond well to topical Minoxidil have a lot of SULT1A1 in their scalp which means increased activity of ABCC3 which pushes the Minoxidil Sulfate out of the cells.

When applying topical minoxidil you are applying the prodrug which can enter the hair follicles without being exported by ABCC3.

So people who don’t respond to Oral Minoxidil should try topical and vice versa.