Pimavanserin: An Inverse Agonist Antipsychotic Drug.

Approximately all clinically useful antipsychotic drugs have known activity as dopamine receptor antagonists, but many of these drugs also are inverse agonists at the serotonin-2A (5HT2A) receptor. Pimavanserin is an inverse agonist at the 5HT2A receptor, with a lower binding affinity at the serotonin-2C receptor and sigma 1 receptor, but no significant binding to dopamine or other receptors. Because of its unique pharmacology, pimavanserin was approved for the treatment of psychosis associated with Parkinson's disease, and it has a low risk for exacerbating motor symptoms compared to standard antipsychotic medications. Whether pimavanserin can treat psychotic symptoms in schizophrenia, psychotic depression, psychotic mania, delirium, or drug-induced psychosis, is not known. Based on its inverse agonist effect at 5HT2A receptors, pimavanserin may have potential for treating symptoms associated with the use of hallucinogen drugs and for treating akathisia associated with antipsychotic medications. [Journal of Psychosocial Nursing and Mental Health Services, 54 (6), 21-24.].