Eltoprazines

Flesinoxan (DU-29,373) is a potent and selective 5-HT1A receptor partial/near-full agonist of the phenylpiperazine class. Originally developed as a potential antihypertensive drug, flesinoxan was later found to possess antidepressant and anxiolytic effects in animal tests. As a result, it was investigated in several small human pilot studies for the treatment of major depressive disorder, and was found to have robust effectiveness and very good tolerability. However, due to "management decisions", the development of flesinoxan was stopped and it was not pursued any further.

Eltoprazine (; developmental code name DU-28,853) is a non-selective serotonin receptor modulator of the phenylpiperazine family which was under development for the treatment of aggression, attention deficit hyperactivity disorder (ADHD), cognition disorders, drug-induced dyskinesia, and psychotic disorders but was never marketed. It has been described as a "serenic" or antiaggressive agent. The drug is taken orally.

Lecozotan is an investigational drug by Wyeth tested for improvement of cognitive functions of Alzheimer's disease patients. , the first Phase III clinical trial has been completed.

S-15535 is a phenylpiperazine drug which is a potent and highly selective 5-HT1A receptor ligand that acts as an agonist and antagonist (weak partial agonist) at the presynaptic and postsynaptic 5-HT1A receptors, respectively. It has anxiolytic and antiaggressive effects.