Encenicline (EVP-6124; MT-4666) acts as a potent partial and selective agonist at alpha-7 nicotinic acetylcholine receptor. Encenicline significantly improved memory function in animal models. FORUM Pharmaceuticals (formerly EnVivo Pharmaceuticals) is developing encenicline for the treatment of cognition disorders such as schizophrenia and for Alzheimer's disease.

(-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine ((-)-3-PPP, also known as preclamol) has a dual action towards to dopamine D2 autoreceptor: it activates it and also acts concomitantly as an antagonist at postsynaptic DA receptors. It was shown, that (-)-3PPP/preclamol was a safe drug for study in the treatment of schizophrenia and may have antipsychotic efficacy. Besides, the motor effects of the drug were evaluated in nine patients with Parkinson's disease using a double-blind, placebo-controlled design. However, the small number of patients manifesting a clinically significant response and the frequently inconsistent effects could indicate that this class of agents may have relatively limited clinical utility.

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.

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.

Bifeprunox, code name DU-127,090 is an atypical antipsychotic agent, which combines minimal D2 receptor agonism with 5-HT receptor agonism. Bifeprunox was in phase III of clinical trials for the treatment of schizophrenia, Bipolar Depression and in phase I for Parkinson's disease, but these studies were discontinued because efficacy data did not support pursuing the existing development strategy of stabilization of non-acute patients with schizophrenia.

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.

Pridopidine is an experimental drug candidate belonging to a class of agents known as dopidines, which act as dopaminergic stabilizers in the central nervous system. As a dopamine stabilizer, pridopidine is thought to reduce the effects of dopamine when there’s too much and increase its effects when there’s too little. Pridopidine, therefore, plays two opposing roles in the brain, which stabilize dopamine levels. In this way, pridopidine is thought to help the brain reestablish a normal balance of neurotransmitters, and thus regain control over motion. Pridopidine intended to treat Huntington’s disease movement symptoms. Pridopidine was well tolerated and had an adverse event profile similar to a placebo.

PF-03654746 is a potent, selective antagonist of the human H3 receptor, developed by Pfizer. It was in the clinical trial phase II for the treatment of excessive daytime sleepiness (EDS) associated with narcolepsy, Tourette syndrome as well as potential anti-allergy applications and in phase I of clinical trial for the treatment of Schizophrenia and Alzheimer's disease, but these investigations were discontinued.

Talnetant (SB-223412) is a selective, orally active neurokinin 3 receptor antagonist and is under development for the potential treatment of several disorders, including irritable bowel syndrome, schizophrenia, chronic obstructive pulmonary disease, cough, overactive bladder and urinary incontinence. The most common adverse effects were headache, fatigue, and nausea.

Sonepiprazole exhibits highly specific binding to the D4 dopamine receptor with more than 100-fold selectivity for the D4 receptor over other receptors, including dopamine, serotonin, and adrenergic receptors. It is a neutral antagonist at the D4 dopamine receptor and is devoid of dopamine agonist activity. Sonepiprazole selectively induces c-fos expression in the prefrontal cortex and blocks behavioral, biochemical, and genomic effects of repeated amphetamine administration in rats. Sonepiprazole was investigated as an antipsychotic for the treatment of schizophrenia in a placebo-controlled clinical trial, but in contrast to its comparator olanzapine no benefits were found and it was not researched further for this indication.