That's not a spironolactone problem; that's a vehicle problem. Use a different vehicle or reduce the alcohol content if it bothers you. Adding some propylene glycol might help too, though it would not reduce the total amount of alcohol applied assuming the amount of spironolactone you apply stays the same. However, since ethanol evaporates very fast, adding the PG might have an effect similar to replacing some of the ethanol with PG. Alternatively, you could replace some of the ethanol with PG by evaporating some of it out of the solution, but if you do that I suggest making sure that you add plenty of antioxidants like BHT, and don't let it sit directly exposed to light or for too long. Ideally, you would evaporate it under reduced pressure, but most people don't have the means to do that at home. One final remark: PG will also stabilize the spironolactone better than alcohol because it is more viscous.
Dave