Drug Risperidone

Question: Discuss about the Article for Drug Risperidone? Answer: Introduction Risperidone is an anti-psychotic drug generally used to treat some mental/mood disorders like schizophrenia, bipolar disorder, autistic disorder etc. It helps to restore the balance between certain hormones in the brain. It was approved by US Food and Drug Administration in December 1993 for treating schizophrenia in adults and later in August 22 2007 it was again approved by FDA for treating the same in adolescents aged between 13 to 17 years. A final approval to manufacture and market tablets of Risperidone was given by the FDA to Aurobindo pharmacy limited. (Goldstone, 2015) Mechanism of action The communication of the nerves in the brain occurs by the release of neurotransmitters. These neurotransmitters get attached with the receptors of other nerves to either stimulate or inhibit their function. In such cases, risperidone is believed to block those receptors to cease abnormal communication between the nerves in psychotic illness cases. This helps in altering the psychotic state of mind of the patient like those in schizophrenic patients. Although its mechanism of action in schizophrenia is unknown but it is found to be mediated through a unique combination of dopamine type 2 (D2) and serotonin type 2 (5HT2) receptor antagonists. It acts as an antagonist for receptors like D2, 5-HT2A, ALPHA 1, ALPHA 2 AND H1. It is an atypical anti-psychotic drug and possesses ability to block D2 and 5HT2A receptors and is a highly selective D3 receptor antagonist. DRD3 plays a potential role in the action of anti-psychotic drugs. (Correia, 2007) In response to risperidone, when Ser9Gly polymorphism was associated in this DRD3 gene no consistent results were found. Being anti-psychotic in nature it reduces dopaminergic neurotransmission .the ability with which it binds with the receptors is inversely proportional to its ki. The higher the ki, the lower is the affinity to bind with a receptor and a higher affinity if the ki of it is low. Its binding potency is different at different receptor sites. Pharmacogenomic Implications of Risperidone Risperidone is found to be safe to prevent extrapyramidal symptoms. Despite being a safe and efficient drug, there are some pharmacogenomic implications that affect the working efficiency of the drug in the routine clinical practices. The metabolism of the drug is accompanied with the involvement of some genes also. The genes that are most involved in the mechanism of action are CYP2D6, CYP3A and ABCB1 which greatly help in predicting the interactions of the drug with different plasma concentrations. Some specific genes like 5HTR2A, DRD2, DRD3, 5-HTTLPR and COMT have been reported to produce negative results in clinical findings. Apart from having a good binding affinity it possess some side effects also such as neuroleptic syndrome (life threatening disorder of nervous system caused by adverse action of anti-psychotic drug), weight gain or polydipsia (excessive thirst), increased cardiovascular and cancer mortality and morbidity rate in adults. (Patrick, 2002) Drug interaction Risperidone gets distributed very rapidly and absorbed into the blood and the intake of food does not have any impact on its absorption therefore it can be taken with or without meals. It gets metabolized into the liver with the action of enzyme CYP 2D6 which is mainly responsible for its metabolism. The drug and its metabolites are greatly eliminated from the body through urine and a small quantity of it through faeces. (Penas, 2013) Conclusion From the above stated details about the drug risperidone it is noticed that risperidone is a safe drug to be used in psychotic disorders. But it is not prescribed to those patients who have hypersensitivity to the drug risperidone. If the patient has hypersensitivity to the drug then it should not be continued to avoid any matter of risk. Hypersensitive reactions or anaphylactic reactions are very likes to occur in patients who continue risperidone for a longer period of time. References College of Psychiatric and Neurologic Pharmacists 2013 Poster Abstracts. (2013).Journal Of Pharmacy Practice,26(3), 304-346. https://dx.doi.org/10.1177/0897190013487674 Correia, C., Vicente, A. (2007). Pharmacogenetics of risperidone response and induced side effects.Personalized Medicine,4(3), 271-293. https://dx.doi.org/10.2217/17410541.4.3.271 Dos Santos-Jnior, A., Henriques, T., de Mello, M., Della Torre, O., Paes, L., Ferreira-Neto, A. et al. (2016). 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