Brexpiprazole
"My son, who is 13, was dx with Bipolar almost 3 years ago and has been on every anti-psychotic drug. His pdoc started him on Rexulti 1 month ago and I have yet to see any improvement. His Dr started him at 2mg for the first 2 weeks and was just increased to 4mg last week. He is also on a low dose of Lamictal, Amantadine and Trazodone. The only side effect I have seen is an increase of his appetite. 
But as for his behavior, nothing. I don't know if this medication works quickly or does it take time. 
Either way, since nothing has changed behaviorally,  the next and last drug he will be prescribed is Clozaril. I know that drug very well, because my 16 year old has been on it since he was 13."