Fluspirilene, a neuroleptic drug, which is used clinically to treat schizophrenic patients, by blocking of dopamine receptors, especially the dopamine D2 receptors. Fluspirilene also displays calcium channel-blocking activity; it inhibits glutamate release primarily by reducing presynaptic Ca2+ influx via N-type Ca2+ channels that also may contribute to the antischizophrenic action of the drug. Recently in the frame of a project of drugs repositioning, fluspirilene was studied as an anti-cancer drug. It was found, that fluspirilene demonstrates a significant inhibitory effect on the proliferation and invasion of glioma cells. Thus, it can be a promising drug for the treatment of glioblastoma. In addition, fluspirilene, as a potential cyclin-dependent kinase 2 inhibitor, was investigated in animal models for the treatment of human hepatocellular carcinoma. Taken into account that fluspirilene has a long history of safe human use, the drug can be applicable in clinical therapy for cancer’s disease immediately.

Pipamperone (INN, USAN, BAN), also known as Carpiperone and Floropipamide or Fluoropipamide, and as Floropipamide hydrochloride (JAN), is a typical antipsychotic of the butyrophenone family used in the treatment of schizophrenia. It is or has been marketed under brand names including Dipiperon, Dipiperal, Piperonil, Piperonyl, and Propitan. Pipamperone acts as an antagonist of the 5-HT2A, 5-HT2B, 5-HT2C D2, D3, D4, α1-adrenergic, and α2-adrenergic receptors. It shows the much higher affinity for the 5-HT2A and D4 receptors over the D2receptor (15-fold in the case of the D4 receptor, and even higher in the case of the 5-HT2A receptor), is regarded as "highly selective" for the former two sites at low doses. Pipamperone has low and likely insignificant affinity for the H1 and mACh receptors, as well as for other serotonin and dopamine receptors. Low-dose pipamperone (5 mg twice daily) has been found to accelerate and enhance the antidepressant effect of citalopram. Pipamperone is approved in some European countries. At its usually recommended antipsychotic dose (120–360 mg/d), it has relatively weak neuroleptic activity because it is only moderately effective as a dopamine D2-receptor antagonist, even at high doses.

Benperidol is a relatively old antipsychotic drug that has been marketed since 1966. It has been used in Germany for 30 years, but is also available in Belgium, Greece, Italy, the Netherlands and the UK. Benperidol is a drug which is a highly potent butyrophenone derivative. It is the most potent neuroleptic on the European market, with chlorpromazine equivalency as high as 75 to 100 (about 150 to 200% potency in terms of dose compared to haloperidol). Benperidol was discovered at Janssen Pharmaceutica in 1961. Benperidol is a potent dopamine receptor antagonist, with a high affinity for the D2-sites. The antipsychotic effects of this drug are primarily due to blockade of the D receptors. In terms of D receptor blockade, benperidol is one of the most potent antipsychotic agents, being approximately eight times more potent than haloperidol. Benperidol also acts as a dopamine antagonist in the chemoreceptor trigger zone, giving rise to antiemetic properties. It is also a weak antagonist at muscarinic, histamine H1, and alpha1-adrenoceptors. Adverse effects include extrapyramidal side effects and tardive dykinesia

Mianserin is a tetracyclic antidepressant used for the treatment of depression. It was investigated as an adjuvant for reduction of negative and cognitive symptoms of schizophrenia, as an aid for opioid detoxification therapy (where it reduced symptoms but lead to higher drop-out rate), and for the treatment of post-traumatic stress disorder (where it was ineffective). Mianserin has a broad spectrum of activity with the most potent binding to 5-HT2A, 5-HT2C, H1, alpha2A and alpha2C receptor.

Xanomeline (LY-246,708) is an orthosteric muscarinic acetylcholine receptor (mAChR) agonist, often referred to as M1/M4-preferring. It is also known to act as a M5 receptor antagonist. Xanomeline was studied in clinical trials phase I in schizophrenia. In Phase II clinical trials in Alzheimer’s patients, xanomeline significantly improved several measures of cognitive function, yet produced unwanted side effects that limited patient compliance. The side effects seem to be associated with rapid metabolism of the alkyloxy side chain following oral administration, resulting in a nonselective, yet active compound with limited therapeutic utility. Despite a second Phase II clinical trial with a patch formulation, the liabilities of xanomeline still outweigh its benefits.

Xanomeline (LY-246,708) is an orthosteric muscarinic acetylcholine receptor (mAChR) agonist, often referred to as M1/M4-preferring. It is also known to act as a M5 receptor antagonist. Xanomeline was studied in clinical trials phase I in schizophrenia. In Phase II clinical trials in Alzheimer’s patients, xanomeline significantly improved several measures of cognitive function, yet produced unwanted side effects that limited patient compliance. The side effects seem to be associated with rapid metabolism of the alkyloxy side chain following oral administration, resulting in a nonselective, yet active compound with limited therapeutic utility. Despite a second Phase II clinical trial with a patch formulation, the liabilities of xanomeline still outweigh its benefits.

Samidorphan, which was developed by Alkermes, is an opioid receptor antagonist that has been co-formulated with olanzapine into a single-dose oral tablet to mitigate the risk of weight gain while providing the therapeutic effect of olanzapine. In June 2021, the Food and Drug Administration (FDA) approved Lybalvi (olanzapine/samidorphan) for indications including treatment of adults with schizophrenia and/or bipolar I disorder (acute manic episodes or acute episodes with mixed features).

Amisulpride, a benzamide derivative, shows a unique therapeutic profile being atypical antipsychotic. At low doses, it enhances dopaminergic neurotransmission by preferentially blocking presynaptic dopamine D2/D3 autoreceptors. At higher doses, amisupride antagonises postsynaptic dopamine D2 and D3 receptors, preferentially in the limbic system rather than the striatum, thereby reducing dopaminergic transmission. In addition its antagonism at serotonin 5-HT7 receptors likely underlies the antidepressant actions. Amisulpride is approved for clinical use in treating schizophrenia in a number of European countries and also for treating dysthymia, a mild form of depression, in Italy.

Cariprazine is an antipsychotic approved by FDA for the treatment of schizophrenia and bipolar I disorder. The drug has a unique clinical action which is explained by its ability to act on dopamine D3 receptors. Pharmacology studies revealed that cariprazine is a dual partial agonist of dopamine D2 and D3 receptors as well as serotonin 5HT1a, 2a and 2b receptors.

Lurasidone is a novel antipsychotic agent approved for the treatment of schizophrenia in a number of countries including the UK and is also approved in the USA and Canada for the treatment of bipolar depression as either a monotherapy or adjunctive therapy with lithium or valproate. In addition, lurasidone is in phase III of a clinical trial for the treatment patient with major depressive disorder and for the treatment of irritability associated with autistic disorder. The mechanism of action of lurasidone, as with other drugs having efficacy in schizophrenia, is unknown but is known, that lurasidone has a high affinity for dopamine D2, serotonin 5-HT2A and serotonin 5-HT7 receptors where it has antagonist effects. In addition, lurasidone is a partial agonist at the serotonin 5-HT1A receptor and has no appreciable affinity for histamine or muscarinic receptors.