Drug information of Risperidone

Risperidone

Drug group:

Risperidone is an antipsychotic medicine . It works by changing the effects of chemicals in the brain.
Risperidone is used to treat schizophrenia in adults and children who are at least 13 years old.
Risperidone is also used to treat symptoms of bipolar disorder (manic depression) in adults and children who are at least 10 years old.
Risperidone is also used to treat symptoms of irritability in autistic children who are 5 to 16 years old.

Mechanism of effect

Risperidone improves negative symptoms of psychoses and reduces incidence of EPS
It has high affinity for serotonin type 2 (5-HT2) receptors; binds to dopamine D2 receptors with 20 times lower affinity than that for 5-HT2 receptors; antagonizes alpha1-adrenergic, alpha2-adrenergic, and histaminergic receptors ; has moderate affinity for serotonin type 1 (5-HT1C, 5-HT1D, 5-HT1A) receptors; has weak affinity for dopamine D1 receptors; has no affinity for muscarinic, beta1-adrenergic, and beta2-adrenergic receptors

Pharmacodynamic

Risperidone is most often used to treat delusional psychosis (including schizophrenia), but risperidone is also used to treat some forms of bipolar disorder and psychotic depression.
It also has shown some success in treating symptoms of Asperger's Syndrome and autism. Risperidone is now the most commonly prescribed antipsychotic medication in the United States.

Pharmacokinetics

Absorption
• Bioavailability: 70%
• Peak plasma time: Extensive metabolizers, 3 hr; poor metabolizers, 17 hr
Distribution
• Protein bound: Risperidone, 90%; metabolite, 77%
• Vd: 1-2 L/kg
Metabolism
• Metabolized in liver by CYP2D6
• Metabolite: 9-hydroxyrisperidone (paliperidone)
Elimination
• Half-life: Extensive metabolizers, 3 hr (parent and metabolite combined); poor metabolizers, 20 hr (parent and metabolite combined); prolonged in renal impairment; free fraction increase in hepatic disease .
• Excretion: Urine (70%), feces (14%)

Dosage

Schizophrenia
PO
• 2 mg/day initially; may be increased in increments of 1-2 mg/day at intervals ≥24 hours
• Recommended target dosage: 2-8 mg/day once daily or divided q12hr (efficacy follows bell-shaped curve; 4-8 mg/day more effective than 12-16 mg/day)
IM
• 12.5-50 mg injected into deltoid or gluteal muscle every 2 weeks; dosage should not be adjusted more frequently than every 4 weeks
• Recommended to establish tolerability of PO risperidone before initiating treatment with IM risperidone
Bipolar Mania
PO
• 2-3 mg/day initially; may be increased if necessary in increments of 1 mg/day at intervals of 24 hours to 6 mg/day; dosage recommendations not available for treatment duration >3 weeks
IM
• 12.5-50 mg injected into deltoid or gluteal muscle every 2 weeks; dosage should not be adjusted more frequently than every 4 weeks
• Recommended to establish tolerability of PO risperidone before initiating treatment with IM risperidone

Drug contraindications

severe hypersensitivity reactions

Alerts

Risperidone is not approved for use in psychotic conditions related to dementia. It may increase the risk of death in older adults with dementia-related conditions.
• Tell your doctor if you have ever had: heart disease, high blood pressure, heart rhythm problems, stroke or heart attack; diabetes (or risk factors such as obesity or family history of diabetes); low white blood cell (WBC) counts; liver or kidney disease; seizures; breast cancer; low bone mineral density; trouble swallowing; Parkinson's disease; or if you are dehydrated.
• The risperidone orally disintegrating tablet may contain phenylalanine. Talk to your doctor before using orally disintegrating tablets if you have phenylketonuria (PKU).
• Taking antipsychotic medication during the last 3 months of pregnancy may cause problems in the newborn, such as withdrawal symptoms, breathing problems, feeding problems, fussiness, tremors, and limp or stiff muscles.
However, you may have withdrawal symptoms or other problems if you stop taking your medicine during pregnancy. If you become pregnant while taking this medicine, do not stop taking it without your doctor's advice.
Risperidone can pass into breast milk and may cause side effects in the nursing baby. You should not breast-feed while using this medicine.
• Do not give this medicine to a child without a doctor's advice.

Points of recommendation

• Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.
Risperidone can be taken with or without food.
• Do not swallow the tablet whole. Allow it to dissolve in your mouth without chewing. If desired, you may drink liquid to help swallow the dissolved tablet.
• While you are taking this medicine, you may be more sensitive to temperature extremes such as very hot or cold conditions. Avoid getting too cold, or becoming overheated or dehydrated. Drink plenty of fluids, especially in hot weather and during exercise. It is easier to become dangerously overheated and dehydrated while you are taking this medication.
Risperidone may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert. Drinking alcohol can increase certain side effects of risperidone.
• Stop using this medicine and call your doctor at once if you have fever, stiff muscles, confusion, sweating, fast or uneven heartbeats, restless muscle movements in your face or neck, tremor (uncontrolled shaking), trouble swallowing, feeling light-headed, or fainting.
IM Administration
• Use supplied diluent for resuspension only .
• Administer within 2 minutes of resuspension; if this is not done, shake vigorously to resuspend

Pregnancy level

C


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