My LO has Parkinson's. He has very severe and adverse reactions to anti psychotic meds. He is now severely depressed. Any meds that work?

He becomes belligerent and aggressive when given the drugs that disagree with him like remeron and Ambien. He is now severely depressed and wants medicinal help. I'm fearful of giving him long acting meds like ambilify in case it disagrees and it will take too long to get it out of his system. Is anybody familiar with something that works well with PD?