Eptapirone (F11440) is a potent, selective, high efficacy 5-HT1A receptor agonist with marked anxiolytic and antidepressant potential. In Vitro: The affinity of Eptapirone (F11440) for 5-HT1Abinding sites (pKi, 8.33) was higher than that of buspirone (pKi , 7.50), and somewhat lower than that of flesinoxan (pKi , 8.91).In vivo, Eptapirone (F11440) was 4- to 20-fold more potent than flesinoxan, and 30- to 60-fold more potent than buspirone, in exerting 5-HT1A agonist activity at pre- and postsynaptic receptors in rats (measured by, for example, its ability to decrease hippocampal extracellular serotonin (5-HT) levels and to increase plasma corticosterone levels, respectively). Eptapirone (F11440), shown here to be a potent, selective, high efficacy 5-HT1Areceptor agonist, appears to have the potential to exert marked anxiolytic and antidepressant activity in humans.[1]