Buthionine sulfoximine (BSO) is a selective inhibitor of γ-glutamylcysteine synthetase (γ-GCS), the rate-limiting enzyme in glutathione (GSH) synthesis. In cancer cells, glutathione depletion significantly increased cytotoxicity via oxidative stress. In addition, in neuroblastoma cells susceptible to Buthionine sulfoximine treatment, DNA damage and cell apoptosis occurred via ROS production. Buthionine sulfoximine plus melphalan was effective in treatment for patients with recurrent/refractory neuroblastoma. Buthionine sulfoximine may also be used to increase the sensitivity of parasites to oxidative antiparasitic drugs. Buthionine sulfoximine has been shown to increase the efficacy of nifurtimox against T. cruzi and has also been shown to be an effective modulator of GSH-mediated chemoresistance by increasing the in vitro cytotoxicity of alkylating agents and radiation. Buthionine sulfoximine has been tested in animal studies and in human phase I trials for adults with solid tumors, with documented clinical responses in patients with melanoma, ovarian carcinoma and small cell carcinoma of the lung treated with the combination of Buthionine sulfoximine and melphalan.

AV608, a 4-aminopiperidine derivative, is a selective, specific, long-acting, orally active and potent nonpeptidic antagonist of the NK-1 receptor. AV-608 had been in phase II clinical trials for the treatment of social phobia and overactive bladder (OAB). This compound was originally discovered by Novartis, and then licensed to Areva Pharmaceuticals in October 2003. Addition this drug was in phase I clinical trial for the treatment of Irritable Bowel Syndrome (IBS), this disease is characterized by chronic abdominal pain and frequent comorbid anxiety. The substance P ⁄ neurokinin-1 receptor system is implicated in the regulation of both pain and anxiety, suggesting a potential therapeutic target in IBS. However, the researches on this drug candidate were discontinued in 2010.

Linarotene is arotinoid derivative. It is an antikeratolytic agent. Linarotene had been in preclinical phase by Ortho Pharmaceutical (Johnson & Johnson) and BASF Pharma for the treatment of skin disorders. However, this research was discontinued.

24-Hydroxycalcidiol (24,25-dihydroxy vitamin D3) is a circulating metabolite of vitamin D3. 24,25(OH)2D3 functions by activation of Vitamin D receprtor and promotion of ostecalcin expression, but is less effective than other D3 metabolite, 1alpha,25(OH)2D3. There is conflicting evidence on efffect of 24-hydroxycalcidiol on bone metabolism. In several animal studies it was demonstrated that 24-hydroxycalcidiol was able to stimulate calcification of bone and restore the reduction in bone mineral apposition rate. However, no beneficial effect of 24R,25(OH)2D3 treatment of postmenapausal women on bone mineral density or bone loss and calcium metabolism were observed.

Vatiquinone is the international non-proprietary name for Edison Pharmaceuticals’ EPI-743, an orally bioavailable small molecule being developed by the company for inherited mitochondrial diseases. EPI-743 is a member of the para-benzoquinone class of drugs. The mechanism of action of EPI-743 involves augmenting the synthesis of glutathione, optimizing metabolic control, enhancing the expression of genetic elements critical for cellular management of oxidative stress, and acting at the mitochondria to regulate electron transport. EPI-743 is a compound being developed by BioElectron (previously known as Edison Pharmaceuticals) to treat Friedreich’s ataxia (FA), a rare, autosomal recessive genetic disorder. The regulation of oxidative stress is disturbed in people with FA. EPI-743 targets NADPH quinone oxidoreductase 1 (NQO1), helping to increase the biosynthesis of glutathione, a compound essential for the control of oxidative stress. The drug does not target any FA-specific biochemical pathways directly, but helps to improve the regulation of cellular energy metabolism in general. Vatiquinone has been investigated for the treatment and prevention of retinopathy, rett syndrome, parkinson's disease, noise-induced hearing loss, and methylmalonic aciduria and homocystinuria, Cblc type. The FDA previously granted orphan drug designation for Edison’s EPI-743 to treat inherited respiratory chain diseases of the mitochondria and Friedreich’s ataxia. The company received orphan drug designation for EPI-743 from the Japanese Ministry of Health, Labour and Welfare and European Medicines Agency Committee on Orphan Products for the treatment of Leigh syndrome.

O-Desmethyl tramadol (O-Desmethyltramadol, O-DSMT) is a metabolite of tramadol. O-Desmethyltramadol is an opioid analgesic and the main active metabolite of tramadol. (+)-O-Desmethyltramadol is the most important metabolite of tramadol produced in the liver after tramadol is consumed. This metabolite is considerably more potent as a μ-opioid agonist than the parent compound. O-desmethyl tramadol, inhibits 5-hydroxytryptamine type 2C receptors expressed in xenopus oocytes. O-desmethyl tramadol inhibits functions of M(1) receptors but has little effect on those of M(3) receptors. O-desmethyl tramadol has been widely used clinically and has analgesic activity.