Hey SpaceInvader, you may want to consider trying to change your vehicle composition.
Ethanol is very directly toxic to your skin and hair follicles (
ref,
ref). When I first started mixing solutions, I used 70% ethanol, but I've gradually learned to reduce this on principle. I now keep ethanol at 30% maximum, and I would go lower if I could, but I need this amount to dissolve my RU sufficiently. Ethanol functions as a
penetration enhancer also, but we don't need too much penetration or we'll end up with the same problems as DMSO was creating.
Furthermore, ethanol evaporates rapidly and does not leave a film or reservoir of compound on the skin the way "sticky" agents do. Thus you may get shorter duration of action and less drug delivery over time with a high alcohol percentage. In principle, with a higher PG solvent, some amount of PG may remain on your skin with daro dissolved in it, acting as a "daro reservoir" which can continue to supply daro to the skin/scalp for a longer duration after application.
Consider trying a 50% PG, 30% ethanol, 20% water solution. I believe this is roughly what Kirkland minoxidil is. Given that you're still having trouble dissolving the daro with your high alcohol vehicle, it suggests daro is more soluble in PG than ethanol. You will likely therefore get better dissolution by increasing the PG content while reducing ethanol.
I have had no trouble dissolving 0.25% daro fully in Kirkland minoxidil. I also had no trouble dissolving even 0.5% daro fully in my usual custom vehicle of 50% PG, 30% ethanol, and 20% water when I was using this higher concentration.