Annette (Gbemudu) Ogbru, PharmD, MBA
Annette (Gbemudu) Ogbru, PharmD, MBA
Dr. Gbemudu received her B.S. in Biochemistry from Nova Southeastern University, her PharmD degree from University of Maryland, and MBA degree from University of Baltimore. She completed a one year post-doctoral fellowship with Rutgers University and Bristol Myers Squibb.
Medical and Pharmacy Editor:
GENERIC NAME: risperidone
BRAND NAME: Risperdal, Risperdal Consta
DRUG CLASS AND MECHANISM: Risperidone is an atypical antipsychotic drug that is used for treating schizophrenia, bipolar mania and autism. Other atypical antipsychotic drugs include Olanzapine (Zyprexa), Quetiapine (Seroquel), Ziprasidone (Geodon), Aripiprazole (Abilify) and paliperidone (Invega). Atypical antipsychotics differ from typical antipsychotics due to the lesser degree of extrapyramidal (movement) side effects and constipation. Risperdal Consta is an injectable, long-acting form of risperidone.
The exact mechanism of action of risperidone is not known, but, like other anti-psychotics, it is believed that risperidone affects the way the brain works by interfering with communication among the brain's nerves. Nerves communicate with each other by making and releasing chemicals called neurotransmitters. The neurotransmitters travel to other nearby nerves where they attach to receptors on the nerves. The attachment of the neurotransmitters either stimulates or inhibits the function of the nearby nerves. Risperidone blocks several of the receptors on nerves including dopamine type 2, serotonin type 2, and alpha 2 adrenergic receptors. It is believed that many psychotic illnesses are caused by abnormal communication among nerves in the brain and that by altering communication through neurotransmitters, risperidone can alter the psychotic state. Risperidone was approved by the FDA in December, 1993.
GENERIC AVAILABLE: Yes, Risperdal. No, Risperdal Consta
PREPARATIONS: Tablets: 0.25, 0.5, 1, 2, 3, and 4 mg. Oral solution: 1 mg/mL. Orally disintegrating tablets: 0.5, 1, 2, 3, and 4 mg. Powder for injection: 12.5, 25, 37.5, and 50 mg.
STORAGE: Tablets should be kept at room temperature, 15-25 C (59-77 F).
PRESCRIBED FOR: Risperidone is used to treat schizophrenia, bipolar mania [as a sole therapy or combination therapy with lithium (Eskalith, Lithobid) or valproate (Depakene, Depacon) and for the treatment of irritability associated with autistic disorder in children and adolescents. Clinical studies involving small numbers of patients have shown some benefit in using risperidone for stuttering and Tourette syndrome (non FDA-approved uses). Another non-FDA approved use of risperidone is for obsessive-compulsive disorders.
DOSING: Risperidone can be administered once or twice daily. Initial dosing is generally 2 mg/day. Dose increases can occur in increments of 1-2 mg/day, as tolerated, to a recommended dose of 4-8 mg/day. In children, risperidone should be initiated at 0.5 mg once daily, and can be increased in increments of 0.5 or 1 mg/day, as tolerated, to a recommended dose of 2.5 mg/day. Risperidone can be given with or without meals. The recommended dose of Risperdal Consta is 25 mg injected into the deltoid or gluteal muscle every two weeks. Patients who have never received risperidone are started on oral risperidone in order to evaluate tolerability. Patients then may be transitioned to Risperdal Consta if oral risperidone is tolerated
DRUG INTERACTIONS: Risperidone may interfere with elimination by the kidneys of clozapine (Clozaril), a different type of antipsychotic medication, causing increased levels of clozapine in the blood. This could increase the risk of side effects with clozapine.
Serotonin reuptake inhibitors such as paroxetine (Paxil), Sertraline (Zoloft), and fluoxetine (Prozac) when taken with risperidone causes the metabolism (breakdown) of risperidone by the liver to be inhibited, which in turn causes elevated blood levels of risperidone, and may increase the risk of adverse reactions.
Antifungal drugs such as fluconazole (Diflucan), itraconazole (Sporanox), and ketoconazole (Nizoral) when taken with risperidone cause the metabolism (breakdown) of risperidone by the liver to be inhibited, which in turn causes elevated blood levels and may increase the risk of adverse reactions.
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