GTS-21 (also known as DMBX-A), a selective alpha-7 nicotinic acetylcholine receptor agonist that has demonstrated memory and cognition enhancement activity in human clinical trials. GTS-21 has been studied in Phase II in patients with schizophrenia and in patients with Alzheimer disease. However, these studies were discontinued. GTS-21 was also involved in phase II to reduce negative affect, improve cognition and/or reduce smoking relapse in healthy adult men and women who are chronic cigarette smokers. However, this study was withdrawn. Besides, GTS-21 has participated in phase II to investigate safety and efficacy in adults with attention-deficit hyperactivity disorder.

Racemethorphan is racemic mixture of Dextromethorphan and Levomethorphan. Racemethorphan is listed under the Single Convention on Narcotic Drugs 1961 and is therefore listed in the United States as a Controlled Substance, specifically as a Narcotic in Schedule II. Dextromethorphan is a non-narcotic morphine derivative widely used as an antitussive. Dextromethorphan is a cough suppressant in many over-the-counter cold and cough medicines. In 2010, the FDA approved the combination product dextromethorphan/quinidine for the treatment of pseudobulbar affect. Dextromethorphan suppresses the cough reflex by a direct action on the cough center in the medulla of the brain. Levomethorphan is an opioid analgesic of the morphinan family that has never been marketed.

Desmethylmoramide is a morpholinopyrrolidine. Being opioid receptor agonist it might be used as narcotic analgesic.

Arbaclofen (STX209, R-baclofen), a selective agonist of GABA-B receptors, has been investigated in clinical trials for the treatment of autism spectrum disorder ASD, phase II and for the treatment of patients with fragile X syndrome in phase III. As a result, the drug did not meet the primary outcome of improved social avoidance in FXS in either study. In spite of positive results in some children with ASD, further study will be needed to replicate and extend these initial findings. Arbaclofen has also been investigated in phase III clinical trials as a treatment for spasticity due to multiple sclerosis.

Velusetrag (TD-5108) is a potent, selective high intrinsic activity serotonin 5-HT(4) receptor agonist. Velusetrag has achieved proof-of-concept in patients with chronic idiopathic constipation and was on phase II of clinical trial for the treatment of Alzheimer's disease and constipation, when studies were discontinued. In addition, velusetrag is on the phase II of clinical trial for the treatment of gastroparesis.

Etalocib (LY-293111 or VML 295) is a potent and orally active leukotriene B4 receptor antagonist of the biphenylphenol class. It efficiently blocks neutrophil activation and subsequent inflammation. Additionally, it exerts antineoplastic properties through induction of cell cycle arrest and apoptosis in tumor cells. Etalocib was being developed for the treatment of inflammatory diseases and solid tumors.

Leteprinim is the synthetic purine. It has both anti-excitotoxic neuroprotective properties and enhances the regenerative response of surviving neurons within the central nervous system. Moreover, the experiments in vitro and in vivo reveal that leteprinim can be administered after an excitotoxic event and still produce neuroprotection. This is clearly crucial for any drug designed to treat stroke or any acute central nervous system injury. Therefore, leteprinim has the pharmacological properties required by a drug intended to treat acute stroke as well as a spinal injury. It may be useful in reducing brain injury; it possesses clinical relevance for the treatment of hypoxic-ischemic encephalopathy in the newborn. Leteprinim has the therapeutic potential for use in clinical trials in the treatment of neuronal deterioration in depression.

GW842166 is a pyrimidine cannabinoid 2 (CB2) receptor agonist that was being developed by GlaxoSmithKline for the treatment of inflammatory pain. It has potent analgesic, anti-inflammatory and anti-hyperalgesic actions in animal models, but without cannabis-like behavioural effects due to its extremely low affinity for the CB1 receptor. GW842166 shows similar potency and efficacy for rat and human recombinant CB2 receptors with EC50 of 91 nM and 63nM, respectively. GW842166 is in Phase 2 trial.

ISPRONICLINE is a partial agonist at the a4b2 subtype of nicotinic acetylcholine receptors (nAChRs) without interaction with other nAChRs or other receptor systems. It has antidepressant, nootropic, and neuroprotective effects. It progressed to phase II clinical trials for the treatment of dementia and Alzheimer's disease but is no longer under development.

Atocalcitol is a vitamin D analogue. A hallmark of vitamin D3 analogues in psoriasis amelioration is the ability to inhibit the proliferation of keratinocytes. Atocalcitol had been in phase II clinical trials for the treatment of psoriasis. However, this research has been discontinued.