You can, as you already said, try antipsychotics, so dopamine-antagonists like Risperidone or Olanzapine, Aripiprazole as they seem to be the most effective according to research. I tried a similar drug called Asenapine but the restlessness was unbearable so I couldn’t really take it for long to see how it affects my stutter. I‘m also currently trying Propranolol (40mg) and feel it maybe helps a bit, but still not conclusive. I also tried Buspirone and some SSRIs which had no effect on me at all (Speaking as well as mental state). Another one that wasn‘t very helpful for me was Baclofen, for which I had high hopes based on a few case reports. My next step is probably trying out Methylphenidate if my doctor is fine with it, because I found a few articles where it helped some patients (and also because I think I might have ADHD; a link between these conditions is suspected). Kind of interesting if you think about Methylphenidate being a dopamine reuptake inhibitor. There seems to be more to the story than too much dopamine in the striatum. Just some anecdotal experiences from me (M28/ Moderate, sometimes severe stutter with only blocks / Multiple speech therapies until I was 19 with limited success, mostly fluency-shaping).