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Antipsychotic Drugs
Published in Sahab Uddin, Rashid Mamunur, Advances in Neuropharmacology, 2020
Harleen Kaur, Ramneek Kaur, Varsha Rani, Kanishka Sharma, Pawan Kumar Maurya
Risperidone is an antipsychotic drug of second generation having an affinity for receptors like α1, α2, D2, H1, and 5-HT2A. Although the mechanism of action is not fully agreed, the recent theories focus mainly on receptors like 5-HT2A and D2 (Butini et al., 2008). From the perspective of pharmacodynamics, the antipsychotics share a common characteristic that is the ability to reduce neurotransmission of dopaminergic. According to the theory of dopamine in schizophrenia, overactivity of mesolimbic pathway explains the positive symptoms of schizophrenia. Cognitive and negative symptoms of schizophrenia are associated with dysfunction of this pathway. Antipsychotic drugs have an ability to inhibit dopamine receptors. A significant proportion of patient reacts poorly toward neuroleptics, especially sufferers with negative symptoms, which include social withdrawal and apathy. Some other neurotransmitters which include 5-hydroxytryptamine acts on receptor 5HT2,which aims to block ritanserin (Miyamoto et al., 2012).
Psychotic disorders
Published in Bhaskar Punukollu, Michael Phelan, Anish Unadkat, MRCPsych Part 1 In a Box, 2019
Bhaskar Punukollu, Michael Phelan, Anish Unadkat
Serotonin: LSD, a hallucinogen, acts at serotonin receptors. Risperidone and clozapine are 5HT2 receptor antagonists. Ritanserin, a selective 5HT2 antagonist, reduces negative symptoms of schizophrenia when given adjunctively with antipsychotics.
Pharmacological Characterization of 5-Hydroxytryptamine Receptors in the Gastrointestinal Tract
Published in T.S. Gaginella, J.J. Galligan, SEROTONIN and GASTROINTESTINAL FUNCTION, 2020
Jeremy D. Gale, Keith T. Bunce
The antagonists ketanserin, ritanserin, and cinanserin can discriminate between 5-HT2A and 5-HT2B receptors. These compounds are potent 5-HT2A receptor antagonists yielding pA2 values of between 8.0 and 10.4.63,64 Ritanserin, however, also has significant binding affinity at both α-adrenoceptor (pKi = 6.5)67 and dopamine D2 receptors (pKi = 7.6).67 Cinanserin has no appreciable antagonist activity at α-adrenoceptors. These compounds are largely inactive at the 5-HT2B receptor,61,67 but are potent 5-HT2C receptor antagonists (ritanserin: pKD = 8.6).65 More recently, a compound with greater than 2000-fold selectivity between 5-HT2A and 5-HT2C has been described.79 This compound, “compound 26”, has high affinity for 5-HT2A binding sites in rat cerebral cortex (pKi= 8.7) and very low affinity for 5-HT2C sites in the same tissue (pKi = 5.4). However, this agent has appreciable affinity for the 5-HT1A binding site (pKi = 7.3) and should be used with caution in tissues with mixed populations of receptors. Another compound of interest is LY 53857, which is a very potent and competitive antagonist at the 5-HT2A receptor, yielding pA2 values of between 8.4 and 10.4.80,81 This compound has no significant antagonist activity at α-adrenoceptor,82 but is a noncompetitive antagonist at the 5-HT2B receptor in the rat gastric fundus.61Table 3 summarizes the drugs used to characterize 5-HT2A receptors.
Structure activity relationship studies on Amb639752: toward the identification of a common pharmacophoric structure for DGKα inhibitors
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Suresh Velnati, Alberto Massarotti, Annamaria Antona, Maria Talmon, Luigia Grazia Fresu, Alessandra Silvia Galetto, Daniela Capello, Alessandra Bertoni, Valentina Mercalli, Andrea Graziani, Gian Cesare Tron, Gianluca Baldanzi
A search on ChEMBL database26 (https://www.ebi.ac.uk/chembl/) show how these two molecules have activity at the same range of concentration with other biological targets, behaving like a sort of promiscuous ligands. Ritanserin, a well-known serotoninergic antagonist, is structurally similar to R59022, differing for an H-F isosteric substitution on a phenyl ring. Despite this small modification, Boroda et al. showed that ritanserin was a DGKα inhibitor (IC50=15 µM) more potent than R59022 and R59949 and with a better pharmacokinetic profile (t1/2=40 h in human)25. However, the comparison of ritanserin IC50 as serotonin antagonist and as DGKα inhibitor, 0.9 nM and 15,000 nM, respectively, reveal that ritanserin is much a powerful serotonin antagonist than a DGK inhibitor. In addition, ritanserin is also a potent inhibitor on dopaminergic receptors with an IC50 of 69 nM27.
The effect of serotonin on penicillin-induced epileptiform activity
Published in International Journal of Neuroscience, 2019
Mehmet Taskiran, Abdulkadir Tasdemir, Nusret Ayyildiz, Mustafa Ayyildiz, Erdal Agar
In the literature, other 5-HT2 receptor antagonists were shown to have mixed effects on various epilepsy models. The dose of 3 mg/kg ritanserin antagonized the protective effects of DOI in the groggy model of absence seizures [28]. Bercovici et al. showed that ketanserin at a dose of 2.5 mg/kg (i.p.) increased the number of slow spike-and-wave discharges (SSWDs) but had mixed results at 5 mg/kg in absence seizures [29]. In a study of Venzi et al., MDL11,939 (0.5 mg/kg, i.p.) and M100,907 (0.5 and 3 mg/kg, i.p.) exhibited the same effects and increased the total time spent in seizure, seizure length and number of seizures in absence seizures [20]. As seen from the literature, 5-HT2 antagonists also have mixed effects on epileptiform activity, like 5-HT2 agonists. This situation suggests that 5-HT2 receptor subunits may have different effects on epileptiform activity. Also, the chemical agents used in experiments can have different affinities at 5-HT2 subunits. When these data are taken together, the 5-HT2 receptor subunits, chemical agents, preferred doses of agents and epilepsy models used may influence the effects of 5-HT2 and serotonin on epileptiform activity.
Pharmacotherapeutic options for co-morbid depression and alcohol dependence
Published in Expert Opinion on Pharmacotherapy, 2019
Thomas Hillemacher, Helge Frieling
In 1993, Monti et al. analyzed the antidepressant efficacy of the serotonin 5-HT2 antagonist ritanserin (10 mg/d) in 18 detoxified inpatients with current DSM-IIIR diagnoses of alcohol dependence and dysthymia [82]. In a 1-month, randomized, placebo-controlled study, patients on ritanserin achieved a statistically significant improvement of their dysthymia versus the placebo group within one week as well as improved sleep parameters. Reports on drinking outcome were not published [82]. No further studies with ritanserin fulfilling our criteria were identified.