risperidone

Action

Antagonizes serotonin₂ and dopamine₂ receptors in CNS. Also binds to alpha₁-and alpha₂-adrenergic receptors and histamine H₁ receptors.

Availability

Oral solution: 1 mg/ml in 30-ml bottles

Powder for injection (extended-release microspheres): 12.5 mg, 25-mg, 37.5-mg, 50-mg vials in dose pack with diluent in prefilled syringes

Tablets: 0.25 mg, 0.5 mg, 1 mg, 2 mg, 3 mg, 4 mg

Tablets (orally disintegrating): 0.5 mg, 1 mg, 2 mg, 3 mg, 4 mg

Indications and dosages

➣ Schizophrenia

Adults: Initially, 2 mg P.O. daily (as once daily or 1 mg b.i.d.). May increase dosage at 24-hour intervals or more in increments of 1 to 2 mg per day, as tolerated, to recommended dosage of 4 to 8 mg/day. In some patients, slower titration may be appropriate. Efficacy has been demonstrated with a range of 4 to 16 mg/day. However, dosages above 6 mg/day for b.i.d. dosing weren't demonstrated to be more efficacious than lower dosages, were associated with more extrapyramidal symptoms and other adverse effects, and generally aren't recommended. Or, 25 mg deep I.M. q 2 weeks; some patients may benefit from a higher dosage (37.5 or 50 mg). Maximum dosage is 50 mg I.M. q 2 weeks. Efficacy hasn't been evaluated for longer than 12 weeks.

Adolescents ages 13 to17: 0.5 mg P.O. as single daily dose in morning or evening. Dosage adjustments, if indicated, should occur at intervals of not less than 24 hours, in increments of 0.5 or 1 mg/day, as tolerated, to recommended dosage of 3 mg/day.

➣ Short-term management of acute manic or mixed episodes associated with bipolar 1 disorder as monotherapy or as adjunct to lithium or valproate

Adults: Initially, 2 to 3 mg/day P.O. May adjust in increments or decrements of 1 mg/day at 24-hour intervals. Range is 1 to 6 mg/day. Or, 25 mg I.M. q 2 weeks; some patients may benefit from higher dosage (37.5 or 50 mg). Make upward adjustments no more frequently than q 4 weeks. Maximum dosage is 50 mg I.M. q 2 weeks.

➣ Short-term management of bipolar 1 disorder as monotherapy

Children and adolescents ages 10 to 17: 0.5 mg P.O. daily as a single daily dose in the morning or evening. May adjust in increments or decrements of 0.5 to 1 mg/day at 24-hour intervals as tolerated, to recommended target dose of 1 to 2.5 mg/day. Range is 1 to 6 mg/day.

➣ Irritability due to autistic disorder

Children and adolescents ages 5 to 17: Initially, 0.25 mg P.O. (Risperdal) daily for patients weighing less than 20 kg (44 lb) and 0.5 mg/day for patients weighing 20 kg or more. After minimum of 4 days, increase as needed to recommended dosage of 0.5 mg/day for patients weighing less than 20 kg and 1 mg/day for patients weighing 20 kg or more. Maintain this dosage for minimum of 14 days. If sufficient clinical response not achieved, consider dosage increases at 2-week or more intervals in increments of 0.25 mg/day for patients weighing less than 20 kg or 0.5 mg/day for patients weighing 20 kg or more. Effective dosage range is 0.5 to 3 mg/day. Once sufficient clinical response has been achieved and maintained, consider gradually lowering dosage to achieve optimal balance of efficacy and safety.

Dosage adjustment

• Mild to moderate hepatic or renal impairment (appropriate oral dosage titration should occur before initiation of I.M. dosing)

• Severe hepatic or renal impairment (with oral use)

• Elderly or debilitated patients

• Concurrent use of enzyme inducers (such as carbamazepine, phenobarbital, phenytoin, rifampin), fluoxetine, or paroxetine

Off-label uses

• Tourette syndrome

Contraindications

• Hypersensitivity to drug

Precautions

Use cautiously in:

• renal or hepatic impairment, cardiovascular disease, prolonged QT interval, dysphagia, hyperprolactinemia, hypothermia or hyperthermia, Parkinson's disease, phenylketonuria, tardive dyskinesia, metabolic changes that may increase cardiovascular or cerebrovascular risk (such as hyperglycemia, dyslipidemia, weight gain), previous diagnosis of breast cancer or prolactindependent tumors

• history of seizures, drug abuse, or suicide attempt

• elderly or debilitated patients

• pregnant patients

• breastfeeding patients (use not recommended)

• children (safety not established for Risperdal Consta, Risperdal M-Tab, and Risperdal in children weighing less than 33 lb [15 kg]), children younger than age 5 with autistic disorder, younger than age 10 with bipolar disorder, or younger than age 13 with schizophrenia (Risperdal).

Administration

• Record baseline blood pressure before starting therapy.

☞ Do not give powder for injection I.V.

• Be aware that oral drug tolerability should be established before starting I.M. therapy in patients who have never taken oral risperidone.

• Be aware that oral risperidone (or another antipsychotic) should be given with the first I.M. injection and continued for 3 weeks (then discontinued) to ensure that adequate therapeutic plasma concentrations are maintained before the main release phase of long-acting risperidone injection.

• When reconstituting powder for injection, use only the diluent and needle supplied.

• Shake vial vigorously for a minimum of 10 seconds to ensure homogeneous suspension. When properly mixed, the suspension appears uniform, thick, and milky with visible particles.

• If 2 minutes elapse before giving injection, shake vial vigorously before administering. Give injection within 6 hours of reconstitution.

• Don't combine two different dose strengths of I.M. drug in a single administration.

• For I.M. use, inject deep into buttock; rotate injection sites between buttocks.

• Be aware that children and adolescents experiencing persistent somnolence may benefit from once-daily Risperdal dose administered at bedtime, from administering half daily dose twice daily, or from reduction of dose.

Adverse reactions

CNS: tremor, parkinsonism, aggressive behavior, dizziness, drowsiness, extrapyramidal reactions, headache, increased dreams, longer sleep periods, insomnia, sedation, fatigue, nervousness, agitation, anxiety, tardive dyskinesia, hyperkinesia, akathisia, transient ischemic attack (TIA), cerebrovascular accident (CVA), neuroleptic malignant syndrome, suicide

CV: orthostatic hypotension, chest pain, tachycardia, arrhythmias

EENT: vision disturbances, rhinitis, sinusitis, pharyngitis

GI: nausea, vomiting, diarrhea, constipation, abdominal pain, dyspepsia, dry mouth, increased salivation, anorexia, dysphagia

GU: difficulty urinating, polyuria, galactorrhea, dysmenorrhea, menorrhagia, decreased libido

Hematologic: leukopenia, neutropenia, agranulocytosis

Metabolic: dyslipidemia, hyperprolactinemia, hyperglycemia, worsening of diabetes mellitus

Musculoskeletal: joint or back pain

Respiratory: cough, dyspnea, upper respiratory tract infection

Skin: pruritus, diaphoresis, rash, dry skin, seborrhea, increased pigmentation, photosensitivity

Other: toothache, fever, impaired temperature regulation, weight changes

Interactions

Drug-drug. Antihistamines, opioids, sedative-hypnotics: additive CNS depression

Carbamazepine: increased metabolism and decreased efficacy of risperidone

Clozapine: decreased metabolism and increased effects of risperidone

Levodopa, other dopamine agonists: decreased antiparkinsonian effects of these drugs

Drug-diagnostic tests. Blood glucose, prolactin: increased levels

Granulocytes, leukocytes, neutrophils: decreased counts

Drug-behaviors. Alcohol use: increased CNS depression

Sun exposure: increased risk of photosensitivity

Patient monitoring

☞ Closely monitor neurologic status, especially for mood changes or suicidal ideation, neuroleptic malignant syndrome (high fever, sweating, unstable blood pressure, stupor, muscle rigidity, and autonomic dysfunction), extrapyramidal reactions, TIA, CVA, and tardive dyskinesia.

☞ Closely monitor CBC with differential, especially during first few months of therapy; discontinue drug if severe neutropenia occurs.

• Monitor blood pressure, particularly for orthostatic hypotension.

• Assess body temperature. Check for fever and other signs and symptoms of infection.

• Monitor patient with diabetes mellitus for worsening of glucose control. Patients with risk factors for diabetes mellitus who are starting treatment with risperidone should undergo fasting blood glucose testing at the beginning of and periodically during treatment. Monitor all patients receiving drug for signs and symptoms of hyperglycemia, including polydipsia, polyuria, polyphagia, and weakness. Also watch for other metabolic changes such as dyslipidemia or significant weight gain.

• Reassess patients periodically to determine need for maintenance treatment.

Patient teaching

• Instruct patient to remove orally disintegrating tablet from blister pack, place on tongue immediately, and swallow as tablet dissolves.

• Tell patient to mix oral solution with water, coffee, orange juice, or low-fat milk. Tell him solution isn't compatible with cola or tea.

• Advise patient to use effective bedtime routine to avoid sleep disorders.

☞ Teach patient to recognize and immediately report signs and symptoms of serious adverse reactions, mood changes or suicidal ideation, including tardive dyskinesia, and neuroleptic malignant syndrome.

• Instruct patient to move slowly when sitting up or standing, to avoid dizziness from sudden blood pressure decrease.

• Tell patient that excessive fluid loss (as from sweating, vomiting, or diarrhea) and inadequate fluid intake increase risk of light-headedness (especially in hot weather).

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.

• Advise female patient to tell prescriber if she is or plans to become pregnant. Caution her not to breastfeed during therapy.

• Advise patient not to drink alcohol.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and behaviors mentioned above.