Eliprodil, also known as SL 82-0715, is a non-competitive NMDA glutamate receptor antagonist, which targets the polyamine modulatory site and is selective for NR2B subunit-containing receptors. Eliprodil was in phase III clinical trial for the treatment of stroke or traumatic brain injury. However, these investigations were failed. One reason suggested for failure was that eliprodil had blocked the synaptic transmission mediated by NMDA receptors, hindering neuronal survival. In addition, eliprodil has been studied in phase II clinical trials for the treatment of Parkinson's disease.

LY404039 [(-)-(1R,4S,5S,6S)-4-amino-2-sulfonylbicyclo[3.1.0]-hexane-4,6-dicarboxylic acid] is an agonist of orthosteric metabotropic glutamate receptor (mGluR)2/3. In addition, it acts as an agonist at dopamine D2 receptors. LY404039 demonstrated broad antipsychotic and anxiolytic efficacy across multiple animal models. LY-2140023 is a methionine amide prodrug of LY-404039 being developed by Eli Lilly & Co for the potential oral treatment of schizophrenia.

Eltoprazine, a 5-HT1A/B receptor partial agonist, was created by Duphar in the 1980s (as DU-28853) and was subsequently developed by Solvay to treat pathological aggression. This drug is in clinical development for the treatment of Parkinson's disease levodopa-induced dyskinesia (PD-LID), Alzheimer's aggression and adult attention deficit hyperactivity disorder (adult ADHD). In addition, was shown, that the drug could be useful for normalizing prefrontal cognitive abilities, reducing aggression and impulsivity, and improving cognitive function in schizophrenia.

Org 25935 (SCH 900435) is a synthetic drug developed by Organon International, which acts as a selective inhibitor of the glycine transporter GlyT-1. In human trial for prevention of relapse in alcohol-dependent patients in Org 25935 demonstrated no benefit over placebo in preventing alcohol relapse. Org 25935 was tested as an adjunctive treatment to atypical antipsychotics in predominant persistent negative symptoms of schizophrenia, where it did not differ significantly from placebo in reducing negative symptoms or improving cognitive functioning. Clinical trials against panic disorder did not show any benefit compared to placebo.

CYR-101 (MIN-101) is a cyclic amide derivative that has high equipotent affinities for 5-HT2A and sigma-2 receptors (Ki of 7.53 nM and 8.19 nM for 5-HT2A and sigma-2, respectively). MIN-101 also shows binding affinity for a1-adrenergic receptors but low or no affinity for muscarinic, cholinergic, and histaminergic receptors. MIN-101 demonstrated statistically significant efficacy in reducing negative symptoms and good tolerability in stable schizophrenia patients. The drug is in phase II clinical trials for the treatment of Schizophrenia.

Tiospirone (TSP) is an atypical antipsychotic drug. Tiaspirone appeared to be a promising antipsychotic agent as it didn`t cause extrapyramidal syndromes. It has 5HT-2 antagonistic properties as well as affinity for D2, 5HT-1a, 5HT-6 and sigma receptors. Tiospirone was in phase III clinical trials for the treatment of attention hyperactivity disorder with Mead Johnson in the USA but its development appears to have been discontinued.

Talaglumetad (also known as LY-544344) is a bicyclohexane derivative patented by Eli Lilly and Company as modulators of metabotropic glutamate receptor. Talaglumetad acts as a prodrug of Eglumegad, a selective agonist of metabotropic glutamate receptors (mGluR2/3) and metabolized to release active compound by both human jejunal homogenates and rat liver homogenates. In experiments on mice, Talaglumetad was found to be as effective as diazepam for treating anxiety symptoms in several standard tests, but without producing any of the negative side effects of diazepam such as sedation and memory impairment.

Butaclamol is an antipsychotic drug, which was studied for the treatment of schizophrenia. This drug has never marketed and now is used in research, because of its action as a dopamine receptor-blocking agent. Butaclamol consists of the two forms: (-)-butaclamol, an inactive drug and (+)-butaclamol, a potent neuroleptic drug.

Fenmetozole is an alpha-2 adrenergic receptor antagonist which was developed for the treatment of schizophrenic and/or depressed patients, however never reached the market. It was also shown that the drug may reduce symptoms of minimal brain dysfunction in children and antagonize the effect of barbiturates and ethanol.

PHA-543613 was discovered by Pfizer and has been under development primarily as a potential treatment of schizophrenia. PHA-543613 acts as an agonist to the Neuronal acetylcholine receptor protein alpha-7 subunit. A single human trial was conducted in healthy human volunteers, but the compound has been studied extensively in rat models for schizophrenia as well as Parkinson's disease and Alzheimer's disease.