These are 5-HT2C, linked to weight gain, 5-HT2A, linked to its antipsychotic action and relief of some of the extrapyramidal side effects experienced with the typical neuroleptics.It has been found that D-amino acid oxidase, the enzyme that catalyses the breakdown of D-amino acids (e.g. D-alanine and D-serine — the neurotransmitters) is inhibited by risperidone.Risperidone acts on the following receptors:
Dopamine receptors: This drug is an antagonist of the D1 (D1, and D5) as well as the D2 family (D2, D3 and D4) receptors, with 70-fold selectivity for the D2 family. It has "tight binding" properties, which means it has a long half-life. Like other antipsychotics, risperidone blocks the mesolimbic pathway, the prefrontal cortex limbic pathway, and the tuberoinfundibular pathway in the central nervous system. Risperidone may induce extrapyramidal side effects, akathisia and tremors, associated with diminished dopaminergic activity in the striatum. It can also cause sexual side effects, galactorrhoea, infertility, gynecomastia and, with chronic use reduced bone mineral density leading to breaks, all of which are associated with increased prolactin secretion.Serotonin receptors: Its action at these receptors results in a relatively lesser tendency to cause extrapyramidal side effects, like the reference substance clozapine.Alpha α1 adrenergic receptors: This action accounts for the orthostatic hypotensive effects and perhaps some of the sedating effects of risperidone.Alpha α2 adrenergic receptors: Risperidones action at these receptors may cause greater positive, negative, affective, and cognitive symptom control.Histamine H1 receptors: effects on these receptors account for its sedation and reduction in vigilance.
Risperidone, sold under the brand name Risperdal among others, is an atypical antipsychotic used to treat schizophrenia and bipolar disorder. It is taken either by mouth or by injection (subcutaneous or intramuscular). The injectable versions are long-acting and last for 2–4 weeks.Common side effects include movement problems, sleepiness, dizziness, trouble seeing, constipation, and increased weight. Serious side effects may include the potentially permanent movement disorder tardive dyskinesia, as well as neuroleptic malignant syndrome, an increased risk of suicide, and high blood sugar levels. In older people with psychosis as a result of dementia, it may increase the risk of death. It is unknown if it is safe for use in pregnancy. Its mechanism of action is not entirely clear, but is believed to be related to its action as a dopamine and serotonin antagonist.Study of risperidone began in the late 1980s and it was approved for sale in the United States in 1993. It is on the World Health Organizations List of Essential Medicines. It is available as a generic medication. In 2019, it was the 149th most commonly prescribed medication in the United States, with more than 4 million prescriptions. Medical uses
Risperidone is mainly used for the treatment of schizophrenia, bipolar disorder, and irritability associated with autism. Schizophrenia
Risperidone is effective in treating psychogenic polydipsia and the acute exacerbations of schizophrenia.Studies evaluating the utility of risperidone by mouth for maintenance therapy have reached varying conclusions.