"damit man 10% minox lösen kann, muss man säure dazugeben...dann liegt aber das minox als salz in ionisierter form und penetriert überhaupt nicht
10% minox ist dann so potent wie 0,5% "
https://www.alopezie.de/fud/index.php?t=msg&goto=397946/

"Minoxidil is a base, which likes to grab a proton in a solution and become an ionic molecule. Our skin does not absorb any ionic molecules (a molecule that is positively or negatively charged) very well. When azelaic acid is added, it will form azelaic acid-minoxidil complex, which is a neutral molecule and can be absorbed by our skin or scalp much more efficiently."
https://www.minoxidilmax.com/15minoxidil_review

"Many drugs are weak acids or bases that are ionised at normal physiological pH. Under these conditions, they are generally poorly absorbed by the membrane. Several techniques have been studied to increase skin absorption of such molecules, including prodrug design, iontophoresis, and ion pairing. In principle, ion pairing involves the addition of an oppositely charged counter-ion to form a neutral ion pair. This neutral species has increased lipophilicity and hence, membrane permeability is increased."
https://books.google.de/books?id=h076BwAAQBAJ&pg=PA121