As expression of immediate-early gene (IEG) in certain brain regions may represent markers of anti-psychotic activity, expression of immediate-early gene mRNA in the prefrontal cortex and striatum was measured. Treatment with F-15,063 resulted in induction of c-fos and fosB mRNA expression in the prefrontal cortex. In the striatum, F-15,063 treatment resulted in induction of all IEGs studied (c-fos, fosB, zif268, c-jun, junB, nor1, nur77, arc).
F-15,063 was tested in several animal models that predict antipsychotic activity to help determine the behavioral profile. Administration of F-15,063 blocked amphetamine and ketamine induced hyperlocomotion, but did not affect baseline, spontaneous locomotor activity. In addition, F-15,063 did not produce catalepsy, a side effect of other antipsychotics, such as haloperidol. This inhibition of catalepsy is 5-HT1A receptor mediated, as pretreatment with the 5-HT1A antagonist WAY-100635 reinstated catalepsy. The level of catalepsy did not increase with chronic dosing, and there was no evidence for serotonin syndrome at clinically relevant doses.
Plasma levels of F-15,063 decreased seven-fold 4 hours after oral administration, and 25-fold after 8 hours. Despite this, there was still a high (65%) level of central D2 occupancy at 4 hours, and it retained its full antipsychotic potential at this time point. Even after 8 hours, F-15,063 still demonstrated some central D2 occupancy, and retained some antipsychotic activity.
^Bruins Slot, LA (October 2009). "F15063, a potential antipsychotic with dopamine D(2)/D(3) receptor antagonist and 5-HT(1A) receptor agonist properties: influence on immediate-early gene expression in rat prefrontal cortex and striatum.". European Journal of Pharmacology620 (1-3): 27–35. doi:10.1016/j.ejphar.2009.08.019. PMID19695244.