NSI-189 is a novel oral drug which was developed by Neuralstem for the treatment of cognitive disorders. Now the drug is being tested in phase II of clinical trials in patients suffering from major depressive disorder. The mechanism of NSI-189 action is explained by its ability to stimulate the generation of new neurons in the hippocampus, however the exact target molecule is still unknown.

Traxoprodil (CP-101,606) is a potent, selective N-Methyl-D-aspartate (NMDA) receptor (NR2B subunit) antagonist under development by Pfizer for its potential as a neuroprotectant in head injury and neurodegenerative disease. It is in phase II trials in the US and in phase I in Japan for the potential treatment of head injury, such as, Depressive Disorder, Major and Parkinson's Disease. CP-101,606 does not protect against glutamate-induced neurotoxicity in cultured cerebellar neurons, up to a dose of 10 uM. These results are consistent with CP-101,606 being a potent NMDA antagonist, selective for the type of NMDA receptor associated with the hippocampus. Some further investigation revealed that CP-101,606 was associated with a dose-related dissociation and amnesia. These results support the hypothesis that glutamate antagonists may be useful antidyskinetic agents. However, future studies will have to determine if the benefits of dyskinesia suppression can be achieved without adverse cognitive effects.

Gaboxadol (or THIP) is a direct GABA mimetic ligand at delta-containing receptors. Gaboxadol went into human clinical trials to test if the drug promoted sleep. It was generally well tolerated. Gaboxadol enhances delta power in NREM sleep in humans. Gaboxadol failed in Phase III for sleep studies. The side effects of Gaboxadol have been described as mild and similar in quality to those of other GABA-mimetics. Gaboxadol is in development with Ovid Therapeutics as a treatment for Angelman syndrome, fragile X syndrome and epilepsy.

DOV 216,303 [(+/-)-1-(3, 4-dichlorophenyl)-3-azabicyclo-[3.1.0] hexane hydrochloride] is the prototype of a class of compounds referred to as "triple" reuptake inhibitors. DOV 216,303 were licensed from Wyeth in 1998. This compound inhibits the reuptake of norepinephrine (NE), serotonin (5-HT), and dopamine (DA), the three neurotransmitters most closely linked to major depressive disorder. In August 2004, DOV entered into a development and commercialization partnership for the triple reuptake inhibitors (DOV 21,947 and DOV 216,303) with Merck for depression.

Dexmecamylamine (TC-5214, also known, as S isomer of mecamylamine) is a positive allosteric modulator of α4β2 neuronal nicotinic receptors, rather than an open-channel blocker. It was evaluated as a potential adjunct treatment for patients with major depressive disorder (MDD). TC-5214 was generally well tolerated, however, the studies were not supportive of an antidepressant effect for TC-5214 in patients with MDD and inadequate response to prior antidepressant therapy. The Phase 2b clinical trial of TC-5214 for the treatment for overactive bladder (OAB) revealed the high dose of TC-5214 demonstrated mixed results on the co-primary endpoints by providing a statistically significant reduction in micturition frequency and an improvement that did not reach statistical significance on episodes of urinary incontinence. As a consequence of these results, this drug was discontinuing further development of TC-5214 in OAB. The study for using TC-5214 in patients with refractory hypertension was also terminated.

DOV 216,303 [(+/-)-1-(3, 4-dichlorophenyl)-3-azabicyclo-[3.1.0] hexane hydrochloride] is the prototype of a class of compounds referred to as "triple" reuptake inhibitors. DOV 216,303 were licensed from Wyeth in 1998. This compound inhibits the reuptake of norepinephrine (NE), serotonin (5-HT), and dopamine (DA), the three neurotransmitters most closely linked to major depressive disorder. In August 2004, DOV entered into a development and commercialization partnership for the triple reuptake inhibitors (DOV 21,947 and DOV 216,303) with Merck for depression.

AstraZeneca was developing AZD-2066, a metabotropic glutamate receptor 5 (mGLUR5) antagonist, for the oral treatment of pain indications (e.g. chronic neuropathic pain and painful diabetic neuropathies), depressive disorders and gastro-oesophageal reflux disease. AZD-2066 had been in phase II clinical trials by AstraZeneca for the treatment of diabetic neuropathic pain and phase I for the treatment of gastrooesophageal reflux disease (GERD). However, this reasearch had being discontinued.

AstraZeneca was developing AZD-2066, a metabotropic glutamate receptor 5 (mGLUR5) antagonist, for the oral treatment of pain indications (e.g. chronic neuropathic pain and painful diabetic neuropathies), depressive disorders and gastro-oesophageal reflux disease. AZD-2066 had been in phase II clinical trials by AstraZeneca for the treatment of diabetic neuropathic pain and phase I for the treatment of gastrooesophageal reflux disease (GERD). However, this reasearch had being discontinued.

DOV 216,303 [(+/-)-1-(3, 4-dichlorophenyl)-3-azabicyclo-[3.1.0] hexane hydrochloride] is the prototype of a class of compounds referred to as "triple" reuptake inhibitors. DOV 216,303 were licensed from Wyeth in 1998. This compound inhibits the reuptake of norepinephrine (NE), serotonin (5-HT), and dopamine (DA), the three neurotransmitters most closely linked to major depressive disorder. In August 2004, DOV entered into a development and commercialization partnership for the triple reuptake inhibitors (DOV 21,947 and DOV 216,303) with Merck for depression.

Orvepitant is a novel generation brain penetrant, selective and potent, small molecule NK-1 receptor antagonist. Orvepitant’s (GW823296) mode of action and developability characteristics made it a suitable development candidate for the treatment of common anxiety disorders, posttraumatic stress disorder and major depressive disorder. It’s in phase II clinical trials as an effective inhibitor of itch-associated response.