Xanomeline works to improve both the positive (new) and negative (deficit) symptoms of schizophrenia.
Xanomeline is a muscarinic M1 and M4 partial agonist and it has been found effective.
However due to ACh being a widely used NT it has many undesirable systemic effects. Therefore it is delivered with trospium, a muscarinic antagonist which does not cross the blood brain barrier thus reducing the change of the drug everywhere but the body.
The proposed mechanism for this is that (not to be memorised again) somehow muscarinic receptors downregulate and upregulate dopamine release where needed when needed depending on the subtype