Spiro needs to get into the blood stream to be effective. That isnt going to happen topically. I took it for about a year before moving to something stronger. It can have some serious effects on blood presssure. One reason I wouldnt recommend it topically is because the dose would not be consistent. The idea behind spiro is to ge tthe blood Testosterone levels down to low...and stable levels which a topical could not provide.
I dont see why you would want to in the first place? The pills arent much larger thn an aspirin and easy to get down.They are usually peppermint flavoured and I could generally do it without even using water.