I would recommend (IF you want to use topical spironolactone) buying it already formulated from that purpose the minoxidil website (the URL is as you would guess from that name.)
Or perhaps some other already-formulated product that you might find. This is the one
I know of.
I personally do not like spironolactone
products because, though a good formulation
will not itself smell, once applied to the
skin it metabolizes, yielding thioacetic acid, which smells exactly like wet dog. Hope you donāt mind sleeping alone