Remlifanserin (; developmental code name ACP-204) is a selective serotonin 5-HT2A receptor inverse agonist which is under development for the treatment of Alzheimer's disease psychosis. It is taken by mouth.
The drug is an improved follow-up compound to its developer's earlier drug pimavanserin (Nuplaizid; ACP-103). It is more potent and selective than pimavanserin as a serotonin 5-HT2A receptor inverse agonist. Remlifanserin shows 32- to 123-fold selectivity for antagonism and inverse agonism of the serotonin 5-HT2A receptor over the serotonin 5-HT2C receptor depending on the bioassay. For comparison, pimavanserin's selectivity was 8- to 37-fold depending on the assay. Remlifanserin shows very low affinity for the serotonin 5-HT2B receptor compared to the serotonin 5-HT2A and 5-HT2C receptors. It is expected to have less QT prolongation than pimavanserin. The drug blocks the head-twitch response induced by the serotonergic psychedelic DOI and the hyperlocomotion induced by the NMDA receptor antagonist dizocilpine (MK-801) in rodents.
Remlifanserin is under development by Acadia Pharmaceuticals. As of January 2025, it is in phase 3 clinical trials.Its clinicaltrials.gov identifier (nct number) is NCT06159673.