ATC-0175 is a potent antagonist with a high affinity for MCH1R and additional affinities for 5-HT1A and 5-HT2B receptors. The receptor binding and the functional assay (MCH-induced increase in [Ca2+]i) indicated that ATC0175 is a noncompetitive antagonist at MCH1Rs. ATC-0175 exhibited anxiolytic effects in numerous animal models of anxiety including the elevated plus-maze test, social interaction test, stress-induced hyperthermia and maternal separation-induced vocalization. ATC-0175 also exhibited antidepressant effects in the forced swimming test. ATC-0175 increased swimming performance without altering climbing behavior, as observed with selective serotonin reuptake inhibitors. ATC0175 has adequate ADME profile (reasonable oral bioavailability and brain penetration) and potent oral activity in animal models. In contrast, ATC-0175 did not affect spontaneous locomotor activity, hexobarbital-induced sleeping time and did not impair rotarod performance. Thus, ATC-0175 may be devoid of unwanted central nervous system side effects, which are sometimes observed with current medications. ATC-0175 has the potential to be effective in the treatment of patients with depression and/or anxiety disorders.

Idazoxan is an alpha2 receptor antagonist which also shows activity at imidazoline I1 and I2 receptors and modulates the release of dopamine. Idazoxan was in phase II development in the US. Later the development of idazoxan for schizophrenia was discontinued. It was also in clinical trials for cognition disorders in United Kingdom, and was also discontinued. Idazoxan is used in scientific research as a tool for the study of alpha 2-adrenoceptors. Idazoxan`s diastereoisomers possess different relative selectivity for alpha2- pre- and postsynaptic receptors: ( )-idazoxan was 7-8 times more potent than (-)-idazoxan in inhibiting p-[3H]aminoclonidine binding, and 40 times more active in antagonizing clonidine at presynaptic level, indicating a better selectivity for alpha2-presynaptic sites. The pre- and postsynaptic alpha2-adrenoceptors have a different affinity for the two enantiomers of idazoxan. Although the stereoisomers are closely related structurally, ( )-idazoxan possesses a stronger affinity for presynaptic sites. This stereoselectivity was less evident for postsynaptic sites. In rats and dogs, both enantiomers antagonized the sympathoinhibitory effects of clonidine. In rats, ( )- idazoxan was 4-7 times more potent than (-)- idazoxan and 3-8 times more than (-)- idazoxan in dogs. A same order of potency was observed against the sedative effects of clonidine and azepexole in chicks, ( )- idazoxan being 8 times more potent than (-)- idazoxan. Although ( )- idazoxan was more potent than (-) idazoxan, binding studies revealed (-)- idazoxan to be more selective than ( )- idazoxan at central sites. It is concluded that ( )- idazoxan antagonizes both alpha-1 and alpha-2 adrenoceptors and (-)- idazoxan is selective for alpha-2 adrenoceptors. ( )- idazoxan is equipotent for antagonizing postsynaptic alpha-I and alpha-2 adrenoceptors. It is also a potent alpha-2 antagonist at presynaptic and central sites and is 4-8 times more potent than (-)- idazoxan but less selective.

Idazoxan is an alpha2 receptor antagonist which also shows activity at imidazoline I1 and I2 receptors and modulates the release of dopamine. Idazoxan was in phase II development in the US. Later the development of idazoxan for schizophrenia was discontinued. It was also in clinical trials for cognition disorders in United Kingdom, and was also discontinued. Idazoxan is used in scientific research as a tool for the study of alpha 2-adrenoceptors. Idazoxan`s diastereoisomers possess different relative selectivity for alpha2- pre- and postsynaptic receptors: (+)-idazoxan was 7-8 times more potent than (-)-idazoxan in inhibiting p-[3H]aminoclonidine binding, and 40 times more active in antagonizing clonidine at presynaptic level, indicating a better selectivity for alpha2-presynaptic sites. The pre- and postsynaptic alpha2-adrenoceptors have a different affinity for the two enantiomers of idazoxan. Although the stereoisomers are closely related structurally, (+)-idazoxan possesses a stronger affinity for presynaptic sites. This stereoselectivity was less evident for postsynaptic sites. In rats and dogs, both enantiomers antagonized the sympathoinhibitory effects of clonidine. In rats, (+)- idazoxan was 4-7 times more potent than (-)- idazoxan and 3-8 times more than (-)- idazoxan in dogs. A same order of potency was observed against the sedative effects of clonidine and azepexole in chicks, (+)- idazoxan being 8 times more potent than (-)- idazoxan. Although (+)- idazoxan was more potent than (-) idazoxan, binding studies revealed (-)- idazoxan to be more selective than (+)- idazoxan at central sites. It is concluded that (+)- idazoxan antagonizes both alpha-1 and alpha-2 adrenoceptors and (-)- idazoxan is selective for alpha-2 adrenoceptors. In the pithed rat, only (-)- idazoxan possesses both alpha-1 and alpha-2 agonistic effects.

AstraZeneca was developing the thiazole AR-AO-14418, a selective inhibitor of glycogen synthase kinase 3β (GSK-3β), for the treatment of Alzheimer's disease and major depressive disorder. AR-AO-14418 is an important research tool in as much as, at concentrations that AR-AO-14418 is able to inhibit GSK3 activity, this compound did not affect the activity of other 26 protein kinases tested, and especially does not inhibit cdc2 and cdk5, two GSK3-related kinases that are inhibited by published GSK3 inhibitors. Furthermore, AR-AO-14418 constitutes a lead compound with therapeutic potential for the treatment of AD, as well as other neurodegenerative disorders. Later preclinical studies of AR-AO-14418 were discontinued.

MK-912 is non-specific alpha-2 adrenergic receptor antagonist, with high affinity for the alpha-2-A, alpha-2B, and alpha-2C variants. Originally developed by Merk & Co, it has been investigated for potential therapeutic properties for the treatment of depression and diabetes. MK-912 is also regularly used as a molecular probe in biomedical studies seeking information about alpha-2 adrenergic receptors.

Gepirone (brand name Travivo) is an investigational azapirone antidepressant and anxiolytic drug in development for the treatment of major depressive disorder but has yet to be marketed. Like other azapirones, it acts as a selective partial agonist of the 5-HT1A receptor. Gepirone has been under development in the U.S. in an extended release form (referred to as Gepirone ER). It has been rejected multiple times by the FDA during the drug approval process and Phase III studies evaluating its use in the treatment of MDD were prematurely terminated. These were the initial Phase III studies of gepirone ER in MDD, and the effective dose range had not been determined. In March 2016, the FDA reversed its decision and gave gepirone ER a positive review, clearing the way for the drug to finally gain market approval in the U.S. In addition to its antidepressant and anxiolytic properties, gepirone has been found to improve symptoms of sexual dysfunction in men and women, similarly to the marketed 5-HT1A receptor agonist flibanserin. The pro-sexual effects appear to be independent of its antidepressant and anxiolytic effects. Mechanism of action studies have demonstrated that gepirone possesses a much greater selectivity for 5-HT1A receptors over dopamine D2 receptors. Long-term studies have shown that gepirone has a differential action at presynaptic (agonist) and post-synaptic (partial agonist) 5-HT1A receptors. Treatment with gepirone ER desensitizes presynaptic 5-HT1A receptors, which decreases serotonin autoregulatory inhibition and enhances activation of postsynaptic 5-HT1A receptors. As a partial agonist gepirone ER acts as an agonist when endogenous serotonin is not present and as an antagonist when endogenous serotonin is present. Overall, gepirone ER increases serotonin production when insufficient amounts are present, and decreases serotonin production when excess amounts are present. Gepirone has been tested in Phase II clinical trial as antidepressant medication for pharmacotherapy for cocaine dependent subjects.

Maprotiline is a tetracyclic antidepressant with similar pharmacological properties to tricyclic antidepressants (TCAs). Similar to TCAs, maprotiline inhibits neuronal norepinephrine reuptake, possesses some anticholinergic activity, and does not affect monoamine oxidase activity. It differs from TCAs in that it does not appear to block serotonin reuptake. Maprotiline may be used to treat depressive affective disorders, including dysthymic disorder (depressive neurosis) and major depressive disorder. Maprotiline is effective at reducing symptoms of anxiety associated with depression. The mechanism of action of maprotiline is not precisely known. It does not act primarily by stimulation of the central nervous system and is not a monoamine oxidase inhibitor. The postulated mechanism of maprotiline is that it acts primarily by potentiation of central adrenergic synapses by blocking reuptake of norepinephrine at nerve endings. This pharmacologic action is thought to be responsible for the drug’s antidepressant and anxiolytic effects. The mean time to peak is 12 hours. The half-life of elimination averages 51 hours.

Triacetin, also known as Glyceryl Triacetate, is a cosmetic biocide, plasticizer, and solvent in cosmetic formulations, at concentrations ranging from 0.8% to 4.0%. It is a commonly used carrier for flavors and fragrances. Triacetin was affirmed as a generally recognized as safe (GRAS) human food ingredient by the Food and Drug Administration (FDA). It is used as an inactive ingredient additive in some drug formulations. It has been used as a plasticizer in the tests of acrylic polymer films for drug delivery. Triacetin is not toxic to animals. However, in one study, it caused erythema, slight edema, alopecia, and desquamation, and did cause some irritation in rabbit eyes. Concentration of triacetin in consumer products is in the range of about 0.005-2 % for cosmetics, and has been reported to be as high as 15-33 % for one specific antifungal drug.

Pregnenolone sulfate is an endogenous neurosteroid with excitatory effects in the brain, acting as a potent negative allosteric modulator of the GABAA receptor, a positive allosteric modulator of the NMDA receptor, and activator of transient receptor potential cation channel TRPM1 and TRPM3. In the model of schizophrenia, treatment with pregnenolone sulfate normalized the hyperlocomotion and stereotypic bouts, and rescued the PPI deficits of dopamine transporter knockout mice. Promnesic properties of pregnenolone sulfate were demonstrated in rat models of spatial memory performance.

Palmitic acid amide (or palmitamide) is a primary fatty acid amide which was studied as a marker of the following diseases: schizophrenia and major depressive disorder.