Remacemide is a low-affinity noncompetitive NMDA receptor antagonist with sodium channel blocking properties. It has been studied for a number of conditions including acute ischemic stroke, epilepsy, Parkinsons Disease, and Huntington's disease. It was concluded, that was unlikely that remacemide would be further developed as an antiepileptic drug. As for other conditions, there no any information in the literature, why remacemide is no longer being developed for them.

Remacemide is a low-affinity noncompetitive NMDA receptor antagonist with sodium channel blocking properties. It has been studied for a number of conditions including acute ischemic stroke, epilepsy, Parkinsons Disease, and Huntington's disease. It was concluded, that was unlikely that remacemide would be further developed as an antiepileptic drug. As for other conditions, there no any information in the literature, why remacemide is no longer being developed for them.

MPEP (2-methyl-6-(phenylethynyl)pyridine) was one of the first compounds found to act a selective antagonist for the metabotropic glutamate receptor subtype mGluR5. It was under development by Novartis in the late 1990's. MPEP was found to produce neuroprotective effects following acute brain injury in animals. MPEP was also found to have positive effects on animal models of depression, anxiety and morphine withdrawl.

Levomethorphan ( L-stereoisomer of racemethorphan) is an opioid analgesic of the morphinan family that has never been marketed. Levomethorphan is a methylated prodrug of levorphanol, that undergoes hepatic demethylation, converting it to the active form. Levomethorphan (via it’s active form levorphanol)functions as a potent agonist of all three of the opioid receptors, μ, κ (κ1 and κ3 but notably not κ2), and δ, as an NMDA receptor antagonist, and as a serotonin-norepinephrine reuptake inhibitor. Via activation of the KOR, levomethorphan can produce dysphoria and psychotomimetic effects such as dissociation and hallucinations. Levomethorphan is listed under the Single Convention on Narcotic Drugs 1961 and is regulated like morphine in most countries. In the United States it is a Schedule II Narcotic controlled substance.

Levomethorphan ( L-stereoisomer of racemethorphan) is an opioid analgesic of the morphinan family that has never been marketed. Levomethorphan is a methylated prodrug of levorphanol, that undergoes hepatic demethylation, converting it to the active form. Levomethorphan (via it’s active form levorphanol)functions as a potent agonist of all three of the opioid receptors, μ, κ (κ1 and κ3 but notably not κ2), and δ, as an NMDA receptor antagonist, and as a serotonin-norepinephrine reuptake inhibitor. Via activation of the KOR, levomethorphan can produce dysphoria and psychotomimetic effects such as dissociation and hallucinations. Levomethorphan is listed under the Single Convention on Narcotic Drugs 1961 and is regulated like morphine in most countries. In the United States it is a Schedule II Narcotic controlled substance.

Indantadol (previously known as CHF-3381) is an oral and noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist and reversible monoamine oxidase-A (MAO-A) inhibitor that is being developed by Vernalis plc, under license from Chiesi Farmaceutici SpA, for the potential treatment of neuropathic pain. In preclinical studies, indantadol exhibited neuroprotective effects after kainate-induced seizures and displayed anticonvulsant and antihyperalgesic activity. Indantadol also caused a dose-dependent decrease in exploratory motility. In a human heat-capsaicin-induced pain model, indantadol at a dose of 500 mg effectively reduced the area of secondary hyperalgesia. The tolerability profile of the drug at single doses up to 600 mg and twice-daily doses up to 400 mg in clinical trials was significantly more favorable than for other NMDA antagonists. Most side effects have been observed to be mild, and include dizziness and asthenia. Indantadol was in phase II clinical trials for the treatment of chronic cough and neuropathic pain. However, these studies had been discontinued.

Ipenoxazone (NC 1200) is a muscle relaxant that is under investigation (phase II) for the treatment of Alzheimer's Dementia, Cognition Disorders. It acts as an Ionotropic glutamate receptor antagonist.

Levomethorphan ( L-stereoisomer of racemethorphan) is an opioid analgesic of the morphinan family that has never been marketed. Levomethorphan is a methylated prodrug of levorphanol, that undergoes hepatic demethylation, converting it to the active form. Levomethorphan (via it’s active form levorphanol)functions as a potent agonist of all three of the opioid receptors, μ, κ (κ1 and κ3 but notably not κ2), and δ, as an NMDA receptor antagonist, and as a serotonin-norepinephrine reuptake inhibitor. Via activation of the KOR, levomethorphan can produce dysphoria and psychotomimetic effects such as dissociation and hallucinations. Levomethorphan is listed under the Single Convention on Narcotic Drugs 1961 and is regulated like morphine in most countries. In the United States it is a Schedule II Narcotic controlled substance.

Rapastinel (formerly known as GLYX-13) is an investigational intravenous formulation of a novel NMDA receptor partial agonist, which is being evaluated for adjunctive treatment of Major depressive disorder, and has shown a rapid onset of antidepressant efficacy 1 day after a single dose in a Phase 2 clinical trial of patients with Major depressive disorder who had an inadequate response to one or more antidepressants. No psychotomimetic or hallucinogenic side effects were observed with rapastinel. Few adverse events were reported by 5% or more of subjects and these were rated as mild or moderate. These included headache, somnolence, dizziness, dysgeusia, and fatigue. On January 29, 2016, Allergan (who acquired Naurex in July 2015) announced that rapastinel had received Breakthrough Therapy designation from the U.S. FDA for adjunctive treatment of major depressive disorder.

Lanicemine is a low-trapping NMDA channel blocker, which was developed by Fisons Pharmaceuticals and later by AstraZeneca for the treatment of the major depressive disorder. The development was terminated in phase II as the drug did not meet the primary endpoint.