Seganserin
Seganserin is a selective serotonin 5-HT2 receptor antagonist which was studied for the treatment of insomnia and anxiety but was never marketed. It acts as a dual serotonin 5-HT2A and 5-HT2C receptor antagonist. The drug blocks the head-twitch response induced by serotonin precursor 5-hydroxytryptophan and the psychedelic drug mescaline in rodents. It has been found to enhance slow wave sleep in clinical studies. The drug's time to peak levels is 1hour and its elimination half-life is 26hours. Seganserin reached phase 2 clinical trials prior to the discontinuation of its development. It was first described in the scientific literature by 1985.