Tideglusib (NP031112, NP-12, Nypta, Noscira SA, Madrid, Spain), a drug, which belongs to the thiadiazolidinone family, is a GSK-3β inhibitor. Tideglusib was in phase II clinical trials for the treatment of Alzheimer disease (AD) and progressive supranuclear palsy. Participants showed no benefit on either of the primary outcome measures or exploratory endpoints and further development in the drug was halted for these two disease. However, Tideglusib is on phase II clinical trial to determine whether drug is safe and efficacious in the treatment of adolescents and adults with congenital and juvenile-onset Myotonic Dystrophy.

Aloxistatin (E64d) is an irreversible and membrane-permeable cysteine protease inhibitor. Aloxistatin was developed for treating muscular dystrophy. Open trials on 73 Duchene’s muscular dystrophy patients were conducted for 3 years at four Japanese national sanatoriums and resulted in some muscle strength improvement but the results were inconclusive and final double-blind studies did not confirm the results. Taisho has discontinued development of aloxistatin for the potential treatment of muscular dystrophy. The  trials completed through Phase 3. In animal models Aloxistatin (100 mg/kg, p.o.) strongly inhibits the cathepsin B&L activities in the skeletal muscle, heart and liver of hamsters. In spinal cord injury (SCI) rats, Aloxistatin provides neuroprotection in SCI lesion and penumbra.Aloxistatin reduces brain amyloid-β and improves memory deficits in Alzheimer's disease animal models by inhibiting cathepsin B activity.

Semagacestat (LY-450139) was a gamma secretase inhibitor being developed as a treatment for Alzheimer's disease by Eli Lilly. It was hoped that the drug would help to delay the onset of severe Alzheimer's disease, and thereby help preserve cognitive and executive functioning and in turn improve patient quality of life. Semagacestat (LY-450139) is designed to inhibit gamma secretase, an enzyme that is involved in the cleavage of APP to beta-amyloid. By decreasing production of beta-amyloid, it is hoped that gamma secretase inhibitors will exert a disease-modifying effect in Alzheimer's disease and thus slow or halt the destruction of nerve cells – the final stage in the amyloid cascade hypothesis. In March 2008 semagacestat (LY-450139) advanced to Phase III development, where it was evaluated in the IDENTITY (Interrupting Alzheimer's Dementia by EvaluatiNg Treatment of AmyloId PaThologY) trial, the first Phase III trial for this new anti-dementia drug. In August 2010, Eli Lilly announced its decision to halt the development of Semagacestat. The decision was taken after analysing the preliminary results of the second Phase III clinical trial of the drug, which indicated that semagacestat failed to slow disease progression. The drug, in fact, worsened cognition and the ability to perform day-to-day activities.

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.

CX 516, a compound synthesized by Cortex Pharmaceuticals using Ampakine® technology licensed from the University of California, was in clinical investigations for the treatment of Alzheimer's disease, schizophrenia, fragile X syndrome and autism, and sleep disorders, however, development of this drug candidate has been discontinued. CX 516 had an extremely short halflife in humans, very low potency and failed to show any benefits in phase II studies. The compound did have a good safety profile, reducing concerns about the toxicity of excess glutamate. Cortex subsequently terminated clinical development of CX 516.

Tenilsetam (CAS 997: ( /-)-3-(2-thienyl)-2-piperazinone), a cognition-enhancing drug successfully used for the treatment of patients suffering from Alzheimer's disease. According to the mechanism proposed, it inhibits advanced glycation end-product (AGE) formation. The beneficial effect of tenilsetam in Alzheimer's disease could come from the interference with AGE-derived crosslinking of amyloid plaques and a decreased inflammatory response to diminished activation of phagocytosing microglia. In addition was shown, that the long-term treatment with tenilsetam inhibited the formation of acellular capillaries without correcting pericyte loss. Was suggested that tenilsetam could be useful for the treatment of early diabetic retinopathy, but then these studies were discontinued.

Nefiracetam is a cyclic derivative of gamma-aminobutyric acid (GABA). It is thought to act by normalising dysfunctional acetylcholine, GABA and possibly monoamine neurotransmitter systems, but it may also facilitate N/L-type calcium channel opening. Nefiracetam has received attention as a treatment for seizures, depression, and dementia. Nefiracetam was found to be extremely testicular toxic in both rats and dogs; it was found to significantly decrease the levels of testicular testosterone leading to atrophy and malformation of sperm.

Epothilone D (KOS-862 or BMS-241027) is an intermediary obtained in the synthesis of members of the epothilone family and is a small-molecule microtubule stabilizer. It was investigated in Phase II trials in colorectal, metastatic breast and non-small-cell lung cancers. However, development was discontinued in 2007 in favor of a second-generation analog with a better safety profile. This drug also was studied for the treatment of Alzheimer's disease. The study ended in October 2013, and evaluation of epothilone D for Alzheimer's disease was subsequently discontinued. The mechanism by which epothilones induce microtubule polymerization appears to be similar to that of paclitaxel, in that epothilones compete with paclitaxel for binding to microtubules and suppress microtubule dynamics in a manner similar to that of paclitaxel.

Eltanolone (pregnanolone) is an endogenous neuro active steroid that is biosynthesized from progesterone. It is a positive allosteric modulator of the GABAA receptor, as well as a negative allosteric modulator of the glycine receptor. There is strong evidence that it is involved in the pathophysiology of premenstrual syndrome, catamenial epilepsy, major depression, and stress-sensitive brain disorders and is known to have sedative, anxiolytic, anesthetic, and anticonvulsant effects. It was investigated for clinical use as a general (intravenous) anesthetic. It produced unwanted side effects such as convulsions on occasion, and for that reason was not marketed. Pregnanolone possesses neuroprotective and neurotrophic properties thus has been through a number of clinical trials including for treatment of traumatic brain injury (TBI), Alzheimer disease, cognitive impairment and fragile X-associated tremor/ataxia syndrome.

Idalopirdine (Lu AE58054) is a Serotonin 6 receptor (5-HT6) antagonist. Idalopirdine exrets good oral bioavailability and robust efficacy in a rat model of cognitive impairment in schizophrenia. In rats idalopirdine potentiates the effects of acetylcholinesterase inhibitor donepezil on two pharmacodynamic biomarkers associated with cognition, i.e. neuronal oscillations and extracellular ACh levels in the hippocampus. Such potentiation could contribute to the procognitive effects of idalopirdine observed in donepezil-treated Alzheimer's disease patients. The compound is being developed by Lundbeck as an adjunctive therapy with acetylcholinesterase inhibitor donepezil, and is in phase III development for the treatment of Alzheimer's disease in multiple countries worldwide. A phase II trial for the treatment of cognitive impairment associated with schizophrenia was conducted; however no recent reports of development for idalopirdine have been identified.