Nelotanserin (APD125) is a potent 5-HT2A inverse agonist(IC50 : 1.7 nM), a moderately potent 5-HT2C partial inverse agonist t(IC50 :79 nM )and a weak 5-HT2B inverse agonistt(IC50 : 791 nM).

5-HT2C receptor:79 nM , 5-HT2A receptor:1.7 nM , 5-HT2B receptor:791 nM

In healthy human volunteers, nelotanserin was rapidly absorbed after oral administration and achieved maximum concentrations 1 h later. EEG effects occurred within 2 to 4 h after dosing, and were consistent with vigilance-lowering. A dose response of nelotanserin was assessed in a postnap insomnia model in healthy subjects. All doses (up to 40 mg) of nelotanserin significantly improved measures of sleep consolidation, including decreases in the number of stage shifts, number of awakenings after sleep onset, microarousal index, and number of sleep bouts, concomitant with increases in sleep bout duration. Nelotanserin did not affect total sleep time, or sleep onset latency. Furthermore, subjective pharmacodynamic effects observed the morning after dosing were minimal and had no functional consequences on psychomotor skills or memory[1].