Quiflapon Sodium (MK-0591; (3-[1-(4-chlorobenzyl)-3-(t-butylthio)-5-(quinolin-2-yl-methoxy)- indol-2-yl]-2,2-dimethyl propanoic acid, previously L-686,708) had been in phase II clinical studies for the treatment of inflammatory bowel disease, but the study was discontinued later, because in spite of MK-591 markedly inhibited Leukotrienes (LT) biosynthesis, it did not differ significantly from placebo in clinical efficacy. Also was discovered, that MK-0591 may modify the airway changes associated with bronchial hyper responsiveness, as well as offer symptomatic relief in asthma. MK-0591 is a selective and specific 5-Lipoxygenase-activating protein (FLAP) inhibitor with an IC50 value of 1.6 nM in a FLAP binding assay. In additional, recently was discovered, that MK591 possesses all major attributes of a standard anti-metastatic agent with significant cancer-selective effect, and suggest that MK591 may turn out to be an effective agent for therapy of castration-resistant, bone-metastatic prostate cancer. Though details of the molecular underpinnings of the anti-metastatic action of MK591 are unknown at this time, this finding gives an opportunity for further exploration to better understand the signaling mechanisms involved by in vitro and in vivo experiments.

Devazepide (L-364718 or MK-329) is a nonpeptide antagonist for the peripheral (type-A) cholecystokinin (CCK) receptor, which has proved effective in blocking the actions of both exogenous and endogenous CCK in several species. It is an orally active antagonist of CCK-stimulated pancreaticobiliary output in man. Devazepide has been developing for the treatment of anxiety, cancer, neuropathic pain however development discontinued.

Hycanthone is a thioxanthene derivative of lucanthone with anti-schistosomal activity and potential antineoplastic activity. It was clinically available for the treatment of human schistosomiasis. Anti-helmintic action relies on its ability to inhibit worm monoamine oxidase and cholinesterases. Hycanthone produced immediate side effects such as hepatotoxicity and gastrointestinal disturbances, and was consequently withdrawn. Hycanthone inhibits apurinic endonuclease-1 (APE1) by direct protein binding. Hycanthone was used in the 1980s as antitumor agents, it was pulled out of Phase II trials.

Derenofyllin (SLV320) is a selective adenosine A1 receptor antagonist, which is under investigation for the treatment of heart failure with renal dysfunction. Adverse events considered related to SLV320 were dizziness, nausea, transient hypertension and transient hypotension.

ATSM CU-64 is an agent for imaging hypoxia in tissues. The agent was developed to be used in PET diagnostic imaging of cancer and showed positive results in phase II of clinical trials in patients with cervical cancer.

Rostafuroxin (PST 2238) is a digitoxygenin derivative, which selectively displaces ouabain from the Na ,K -ATPase receptor. PST 2238, at concentrations up to 10−4 M, did not show any significant interaction with a- and b-adrenergic, D1, D2, D3, 5-HT1, 5-HT2, H1, H2, M1, M2, A1, A2, Ca2 , Na , or K channel–associated receptors, AT1, AT2, ETa, ETb, GABA, thromboxane, vasopressin, angiotensin II, or the steorid-hormone receptors (androgen, progestogen, estrogen and mineralocorticoid), confirming that PST 2238 is specific for Na ,K -ATPase. Rostafuroxin has been developed in an attempt to unravel the contribution of mutated adducin and endogenous ouabain in the pathogenesis of hypertension. The compound lowered blood pressure in Milan hypertensive rats and humans. Rostafuroxine had been in phase II clinical trials for the treatment of hypertension. Following adverse events in Rostafuroxin group were described: dizziness, headache, upper respiratory tract infections, high blood pressure.

Talarozole (formerly R115866) is a new highly potent and selective azole derivative, which inhibits cytochrome-P450-dependent all-trans-retinoic acid catabolism by blocking the cytochrome P450 enzyme isoform CYP26, a retinoic acid hydroxylase. It is in clinical development for the treatment of psoriasis and acne. However, no local pharmacokinetic data on the diffusion behaviour of talarozole in the skin itself are available. As topical application might be an interesting alternative to oral therapy because of the reduced systemic side effects. The distribution of talarozole within the skin was investigated: 80% was located in the epidermis, while the remaining 20% was found in the dermis. The epidermal concentration of talarozole achieved after a single topical application was sufficiently high to enable the potential induction of local retinoid-like effects.

Misonidazole is a nitroimidazole with radiosensitizing and antineoplastic properties. Exhibiting high electron affinity, misonidazole induces the formation of free radicals and depletes radioprotective thiols, thereby sensitizing hypoxic cells to the cytotoxic effects of ionizing radiation. This single-strand breaks in DNA induced by this agent result in the inhibition of DNA synthesis. The drug also possesses a substantial cytotoxic effect, independent of radiation, which is selectively expressed in hypoxic cells. Misonidazole may be cytotoxic to the normal hypoxic tissues in the human body, making this became a major concern in the clinical application of the drug. Misonidazole leads to strand breaks in cellular DNA and those cells which fail to survive also fail to repair these strand breaks. Misonidazole depletes intracellular glutathione and is more toxic in glutathione depleted cells.

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.

Basimglurant is a potent, selective, and safe mGlu5 inhibitor with good oral bioavailability and long half-life supportive of once-daily administration, good brain penetration, and high in vivo potency. It has antidepressant properties that are corroborated by its functional magnetic imaging profile as well as anxiolytic-like and antinociceptive features. In electroencephalography recordings, basimglurant shows wake-promoting effects followed by increased delta power during subsequent non-rapid eye movement sleep. Basimglurant has favorable drug-like properties, a differentiated molecular mechanism of action, and antidepressant-like features that suggest the possibility of also addressing important comorbidities of MDD including anxiety and pain as well as daytime sleepiness and apathy or lethargy. Basimglurant is being under development by Roche for the treatment of treatment-resistant depression (as an adjunct). It is in phase II clinical trials for this indication.