Pimavanserin

Pimavanserin (ACP-103) is a drug developed by Acadia Pharmaceuticals which acts as an inverse agonist on the serotonin receptor subtype 5-HT2A, with 10x selectivity over 5-HT2C, and no significant affinity or activity at 5-HT2B or dopamine receptors. As of September 3 2009, pimavanserin has not met expectations for Phase III clinical trials for the treatment of Parkinson's disease psychosis, and is in Phase II trials for adjunctive treatment of schizophrenia alongside an antipsychotic medication. It is expected to improve the effectiveness and side effect profile of antipsychotics.