Zimeldine was one of the first selective serotonin reuptake inhibitors to be marketed as an antidepressant under the brand names Zimeldine, Normud, and Zelmid. Zimelidine was developed in the late 1970s and early 1980s by Arvid Carlsson, who was then working for the Swedish company Astra AB. While zimelidine had a very favorable safety profile, within a year and a half of its introduction, rare case reports of Guillain–Barré syndrome emerged that appeared to be caused by the drug, prompting its withdrawl from the market.

S-Adenosylmethionine (often referred to as SAMe) is a methyl donor and a cofactor for enzyme-catalyzed methylations, including catechol O-methyltransferase (COMT) and DNA methyltransferases (DNMT). Although present in all cells, it is concentrated in liver where 85% of all methylation reactions occur. SAM is anti-apoptotic in normal hepatocytes and normal colon epithelial cells but pro-apoptotic in liver human hepatocellular carcinoma (HCC), HepG2 cells and colon cancer cells. Because of structural instability, stable salt forms of SAM are required for its use as an oral drug. The commonly used salts: tosylate, butanedisulfonate, disulfate tosylate, disulfate ditosylate, and disulfate monotosylate. SAMe has been marketed in some European countries since the mid-1980s for the treatment of depression and for other medical conditions such as osteoarthritis (joint disease that causes joint pain and stiffness), fibromyalgia (widespread pain and stiffness). In addition, it is used to treat liver disease and migraine headaches. However, it is not formally approved in the UK for the treatment of depression, and in the USA, it is classified only as a dietary supplement. Some research suggests that it is more effective than placebo in treating mild-to-moderate depression and is just as effective as antidepressant medications without the side effects (headaches, sleeplessness, and sexual dysfunction). In addition, antidepressants tend to take 6 to 8 weeks to begin working, while It seems to begin more quickly. Researchers are not sure how SAMe works to relieve depression. But they speculate it might increase the amount of serotonin in the brain just as some antidepressants do. Many studies have examined injectable forms of SAMe, not oral supplements.

Zimeldine was one of the first selective serotonin reuptake inhibitors to be marketed as an antidepressant under the brand names Zimeldine, Normud, and Zelmid. Zimelidine was developed in the late 1970s and early 1980s by Arvid Carlsson, who was then working for the Swedish company Astra AB. While zimelidine had a very favorable safety profile, within a year and a half of its introduction, rare case reports of Guillain–Barré syndrome emerged that appeared to be caused by the drug, prompting its withdrawl from the market.

Raclopride is a salicylamide neuroleptic, that acts as a selective antagonist of D2 dopamine receptors both in vitro and in vivo. Tritium-labelled raclopride has properties that demonstrate its usefulness as a radioligand for the labelling of dopamine-D2 receptors : 3H-Raclopride has a high affinity for the rat and human dopamine-D2 receptors, the non-specific binding of 3H-raclopride is very low, not exceeding 5% of the total binding and the distribution of the 3H-raclopride binding sites in the brain closely correlates with the dopaminergic innervation. The binding of 3H-raclopride is blocked by dopamine-D2 agonists and antagonists, while the D1 agonist SKF 38393 and the Dl antagonist SCH 23390 have much less potency. The interaction of dopamine with 3H-raclopride binding results in a shallow competition curve, which suggests that 3H-raclopride, similar to other dopamine-D2 radioligands, labels both high and low agonist affinity states of the dopamine-D2 receptor. The in vivo receptor binding studies performed with 3H-raclopride also demonstrate its favorable properties as a dopamine-D2 receptor marker in vivo In contrast to some other compounds used as radioligands, raclopride enters the brain readily and binds with a low component of non-specific binding in all dopamine-rich brain areas. A saturation curve may be achieved in vivo binding studies since injections of increasing concentrations of 3H-raclopride appears to be saturated at concentrations above 25 mkCi (corresponding to approximately 5 nmol/kg). Raclopride antagonizes apomorphine-induced hyperactivity in the rat at low doses (ED50 = 130 nM/kg i.p.) but induces catalepsy only at much higher doses (ED50 = 27 mkM/kg i.p.). Radiolabelled raclopride has been used as a ligand for in vitro and in vivo autoradiography in rat and primate brains. Raclopride C 11 is used with positron emission tomography (PET) as a clinical research tool to determine dopamine type 2 (D 2) receptor density in the human brain under normal and pathological conditions. For example, raclopride C 11 used in PET studies has served to confirm the age-related decrease in striatal dopamine D2 receptor density, which may be associated with a decline in the motor as well as cognitive functions. In patients with Alzheimer's disease, raclopride C 11 may be used to examine neuroreceptor distribution and quantities, which may help in the analysis of degenerative alterations of neuron populations and neuroreceptor systems in patients with this disease. In Huntington's disease, in which degeneration of neostriatal interneurons occurs (postsynaptic to the dopaminergic input), specific binding of raclopride C 11 to D 2 receptors may serve as one of the parameters in predicting performance in cognitive tasks.

Bifemelane is a psychotropic drug, was found to inhibit monoamine oxidase (MAO). It inhibited type A MAO (MAO-A) competitively and type B (MAO-B) noncompetitively and it was a more potent inhibitor of MAO-A than of MAO-B. Bifemelane is an antidepressant and cerebral activator that is used in Japan for the treatment of cerebral infarction patients with depressive symptoms, and in the treatment of senile dementia as well. It also appears to be useful in the treatment of glaucoma.

Raclopride is a salicylamide neuroleptic, that acts as a selective antagonist of D2 dopamine receptors both in vitro and in vivo. Tritium-labelled raclopride has properties that demonstrate its usefulness as a radioligand for the labelling of dopamine-D2 receptors : 3H-Raclopride has a high affinity for the rat and human dopamine-D2 receptors, the non-specific binding of 3H-raclopride is very low, not exceeding 5% of the total binding and the distribution of the 3H-raclopride binding sites in the brain closely correlates with the dopaminergic innervation. The binding of 3H-raclopride is blocked by dopamine-D2 agonists and antagonists, while the D1 agonist SKF 38393 and the Dl antagonist SCH 23390 have much less potency. The interaction of dopamine with 3H-raclopride binding results in a shallow competition curve, which suggests that 3H-raclopride, similar to other dopamine-D2 radioligands, labels both high and low agonist affinity states of the dopamine-D2 receptor. The in vivo receptor binding studies performed with 3H-raclopride also demonstrate its favorable properties as a dopamine-D2 receptor marker in vivo In contrast to some other compounds used as radioligands, raclopride enters the brain readily and binds with a low component of non-specific binding in all dopamine-rich brain areas. A saturation curve may be achieved in vivo binding studies since injections of increasing concentrations of 3H-raclopride appears to be saturated at concentrations above 25 mkCi (corresponding to approximately 5 nmol/kg). Raclopride antagonizes apomorphine-induced hyperactivity in the rat at low doses (ED50 = 130 nM/kg i.p.) but induces catalepsy only at much higher doses (ED50 = 27 mkM/kg i.p.). Radiolabelled raclopride has been used as a ligand for in vitro and in vivo autoradiography in rat and primate brains. Raclopride C 11 is used with positron emission tomography (PET) as a clinical research tool to determine dopamine type 2 (D 2) receptor density in the human brain under normal and pathological conditions. For example, raclopride C 11 used in PET studies has served to confirm the age-related decrease in striatal dopamine D2 receptor density, which may be associated with a decline in the motor as well as cognitive functions. In patients with Alzheimer's disease, raclopride C 11 may be used to examine neuroreceptor distribution and quantities, which may help in the analysis of degenerative alterations of neuron populations and neuroreceptor systems in patients with this disease. In Huntington's disease, in which degeneration of neostriatal interneurons occurs (postsynaptic to the dopaminergic input), specific binding of raclopride C 11 to D 2 receptors may serve as one of the parameters in predicting performance in cognitive tasks.

Melitracen (HCl) is a tricyclic antidepressant with actions and effects similar to amitriptyline.Melitracen (HCl) is given orally in the treatment of depression. It should be withdrawn gradually to reduce the risk of withdrawl symptoms. Melitracen (HCl) is primarily indicated in conditions like Anxiety, Asthenia, Depression, gastro-intestinal disorders associated with anxiety and agitation. Melitracen is marketed in Europe and Japan by Lundbeck and Takeda, respectively, for the treatment of depression and anxiety. In addition to single drug preparations, it is also available as Deanxit, a combination product containing both melitracen and flupentixol. The way this drug works hasn’t been thoroughly researched, but some hypothesize that it may work similarly to the drugs Imipramine and Amitriptyline. In comparison to older TCAs, this drug is thought to work more quickly with more favorable side effects.

Lofepramine is a tricyclic antidepressant that is structurally similar to imipramine and is extensively metabolised to desipramine. In the absence of other major pharmacological effects it appears that its antidepressant activity stems from the facilitation of noradrenergic neurotransmission by uptake inhibition, and possibly by the additional facilitation of serotoninergic neurotransmission. The overall therapeutic efficacy of lofepramine is comparable to that of imipramine, amitriptyline, clomipramine, maprotiline and mianserin in patients with depression of varying severity, and coexisting anxiety. Lofepramine is a strong inhibitor of norepinephrine reuptake (Ki=5.4 nM) and a moderate inhibitor of serotonin reuptake (Ki=70 nM). It is a weak-intermediate level antagonist of the muscarinic acetylcholine receptors.Lofepramine is licensed for the treatment of depression in the United Kingdom.

Dibenzepin is a tricyclic antidepressant of the dibenzo-epine group. It is a selective noradrenaline uptake inhibitor, which exhibits in vitro and in vivo imipramine-like effects. It binds strongly to histamine H1 receptors in the brain and, to a lesser extent, to cholinergic receptors. The pharmacological profile of dibenzepin corresponds widely to its biochemical properties: histamine antagonism, tetrabenazine antagonism, potentiation of various noradrenergic effects and anticholinergic effects. Dibenzepin is only available in European countries for the treatment of depression.

Doxepin is a dibenzoxepin tricyclic antidepressant marketed worldwide. It is a white crystalline solid readily soluble in water, lower alcohols and chloroform. The mechanism of action of doxepin is not definitely known. It is not a central nervous system stimulant nor a monoamine oxidase inhibitor. The current hypothesis is that the clinical effects are due, at least in part, to influences on the adrenergic activity at the synapses so that deactivation of norepinephrine by reuptake into the nerve terminals is prevented. Antidepressants may increase risk of suicidal thinking and behavior (suicidality) in children, adolescents, and young adults (18–24 years of age) with major depressive disorder and other psychiatric disorders. Drowsiness is the most commonly noticed side effect. This tends to disappear as therapy is continued. Other infrequently reported CNS side effects are confusion, disorientation, hallucinations, numbness, paresthesias, ataxia, extrapyramidal symptoms, seizures, tardive dyskinesia, and tremor. : Cardiovascular effects including hypotension, hypertension, and tachycardia have been reported occasionally. Skin rash, edema, photosensitization, and pruritus have occasionally occurred. Eosinophilia has been reported in a few patients. There have been occasional reports of bone marrow depression manifesting as agranulocytosis, leukopenia, thrombocytopenia, and purpura. Doxepin is used to treat depression, anxiety disorders, itchiness, trouble sleeping, and as a second-line treatment of chronic idiopathic urticaria (hives). Its oral formulations are FDA-approved for the treatment of depression, anxiety, and insomnia and its topical formulations are FDA-approved the short-term management (up to 8 days) of atopic dermatitis and lichen simplex chronicus. Whereas in Australia and the UK, the only licensed indication(s) is/are in the treatment of major depression and pruritus in eczema, respectively.