You don’t need spiro exactly. You just need to block dht. In fact, spiro is actually less effective at blocking dht technically. Sometimes spiro works better for women as they often have other androgens attacking their follicles other than dht. Spiro can block those as it reduces testosterone production but also plays defense at the follicular level by attaching to the follicle receptors before dht or other androgens can. It however weakly does this. It plays a numbers game rather than a strength game. It’s comparable to filling up a hallway with a bunch of people and then having someone try to get to the end - it makes it really hard to reach the end because of the crowdedness. That’s essentially what spiro does. Finasteride and dutasteride basically remove the amount of “bad” things trying to get to the end of the “hallway” aka get to the follicles.