Risperidone
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Risperidone
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| Systematic (IUPAC) name | |
| 4-[2-[4-(6-fluorobenzo[d]isoxazol-3-yl)- 1-piperidyl]ethyl]-3-methyl- 2,6-diazabicyclo[4.4.0]deca-1,3-dien-5-one |
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| Identifiers | |
| CAS number | |
| ATC code | N05 |
| PubChem | |
| DrugBank | |
| Chemical data | |
| Formula | C23H27FN4O2 |
| Mol. mass | 410.485 g/mol |
| Pharmacokinetic data | |
| Bioavailability | 70% (oral) |
| Metabolism | Hepatic (CYP2D6-mediated) |
| Half life | 3–20 hours |
| Excretion | Urinary |
| Therapeutic considerations | |
| Pregnancy cat. |
C |
| Legal status |
℞ Prescription only |
| Routes | Oral and extended-release intramuscular injection |
Risperidone (sold under the trade names Belivon, Rispen and Risperdal in the United States) is an atypical antipsychotic medication developed by Janssen Pharmaceutica. It was approved by the United States Food and Drug Administration (FDA) in 1993. It is most often used to treat delusional psychosis (including schizophrenia), but risperidone (like other atypical antipsychotics) is also used to treat some forms of bipolar disorder, psychotic depression, obsessive-compulsive disorder and Tourette syndrome.
Generally lower doses are used for autistic spectrum disorders than are used for schizophrenia and other forms of psychosis; risperidone has received approval from the Food and Drug Administration (FDA) for symptomatic treatment of irritability in autistic children and adolescents.[1]
Risperidone is now the most commonly prescribed antipsychotic medication in the United States.[citation needed] Janssen patent on Risperdal expires on December 29, 2007, opening the market for cheaper generic versions of the drug from other companies.
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[edit] Side effects
Common side effects include nausea, anxiety, dizziness, insomnia, low blood pressure, muscle stiffness, muscle pain, sedation, tremors, increased salivation and weight gain (it is not uncommon for patients taking risperdal over long periods to gain upwards of 50 pounds or even more). It has also been known to cause sexual dysfunction such as retrograde ejaculation.
Occasionally breast tenderness and eventually lactation in both genders may occur. Many antipsychotics are known to increase prolactin because they inhibit dopamine. However, risperidone is known to increase prolactin to a greater extent than most other antipsychotics, such as quetiapine. It is thought that once risperidone raises prolactin, it may cause tumors in the pituitary gland. This may recur even if the patient has switched to a different antipsychotic.[2]
Like all antipsychotics, risperidone can potentially cause tardive dyskinesia (TD), extrapyramidal symptoms (EPS), and neuroleptic malignant syndrome (NMS), although the risk is generally less than for the older typical antipsychotics.
Also, like all atypical antipsychotics, risperidone can trigger diabetes and more serious conditions of glucose metabolism, including ketoacidosis and hyperosmolar coma.[3]
[edit] Pharmacology
Risperidone is a very strong dopamine blocker (antagonist); i.e., it inhibits functioning of postsynaptic dopamine receptors.
Risperidone also acts as a 5-HT2A antagonist, and can be used to quickly and effectively block the effects of 5-HT2A agonist drugs such as LSD. However, the use of antipsychotics on people under the influence of LSD is reportedly extremely unpleasant, with some describing it as a "chemical straightjacket." As a result, Valium is often recommended to reduce the anxiety of a bad trip.
It reaches peak plasma levels quickly regardless of whether it is administered as a liquid or pills. The strong dopamine-blocking reaction is known to make some people feel nauseated if they do things that normally trigger the dopamine response, such as eat a pleasing meal or experience orgasm. Risperidone is metabolised fairly quickly so this potential for nausea subsides usually in two to three hours.
[edit] References
- ^ FDA (October 2, 2006). FDA Approves the First Drug to Treat Irritability Associated with Autism, Risperdal. Press release. Retrieved on 2006-10-02.
- ^ Szarfman A, Tonning J, Levine J, Doraiswamy P (2006). "Atypical antipsychotics and pituitary tumors: a pharmacovigilance study.". Pharmacotherapy 26 (6): 748-58. PMID 16716128.
- ^ FDA (April 19, 2004). FDA Warning Letter. Press release. Retrieved on 2006-10-02.
[edit] External links
- Drugs.com Professional information on risperidone
- Drugs.com Consumer information on risperidone
- Janssen L.P. official web site on Risperdal (risperidone)
- PubChem Substance Summary: Risperidone National Center for Biotechnology Information.
