ACP-103, a 5-HT2A receptor inverse agonist.

ACADIA Pharmaceuticals is developing ACP-103, lead compound in a series of 5-HT2A inverse agonists, as a potential antipsychotic agent and for the potential treatment of insomnia. Phase II clinical trials in treatment-induced psychosis in Parkinson's disease (PD) patients and in schizophrenic patients are ongoing, as are phase II trials evaluating the effects of the drug on PD symptoms and dyskinesias.