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Am Fam Physician. 2009;79(12):1104-1107

Author disclosure: Nothing to disclose.

Risperidone (Risperdal) is a mixed serotonin-dopamine antagonist labeled to treat schizophrenia and mania associated with bipolar I disorder in adults. It was recently approved for the treatment of irritability associated with autistic disorder in children five to 17 years of age. Off-label uses include treatment of other symptoms of autistic disorder, including aggression, self-injurious behavior, hyperactivity, and inattention.1-3

NameStarting dosageDose formApproximate monthly cost*
Risperidone (Risperdal)0.25 mg per day in children weighing less than 44 lb (20 kg); 0.5 mg per day in persons weighing 44 lb or more
Effective dose range of 0.5 to 3 mg per day
0.25-, 0.5-, 1-, 2-, 3-, and 4-mg tablets
0.5-, 1-, 2-, 3-, and 4-mg rapidly disintegrating tablets
1 mg per mL oral solution
$125 (0.25-mg tablets)
$137 (0.5-mg tablets)

SAFETY

Extrapyramidal symptoms (e.g., dyskinesia, tremor, rigidity, difficulty swallowing, akathisia), some of which require treatment, occur in up to 27.5 percent of patients and are variably reported in short-term studies of children.1,2,4 To date, studies in children have been small and of short duration; the actual likelihood of extrapyramidal symptoms is not well defined. In one study of adults receiving risperidone, only one of 31 patients developed a movement-related symptom in the form of an abnormal gait.5 Overall, risperidone was well tolerated.

Prolactin levels are increased with risperidone; however, the clinical significance of this increase is unknown because symptoms typically do not occur.4,6 Unlike haloperidol (formerly Haldol), risperidone has not been shown to increase the QT interval.7 Risperidone is U.S. Food and Drug Administration pregnancy category C.8

TOLERABILITY

Most patients (50 to 75 percent) will experience fatigue or drowsiness with risperidone.1,2 Excess salivation occurs in 10 to 27 percent of patients. Ten to 25 percent of patients exhibit weight gain, with mean increases of 5 lb, 15 oz to 6 lb, 8 oz (2.70 to 2.96 kg) in patients receiving risperidone in short-term studies (eight weeks).1,2,6 In longer-term studies (six months), average weight gain was 11 lb to 13 lb, 4 oz (5 to 6 kg).9,10

EFFECTIVENESS

As shown in short-term studies (six months or less), risperidone improves disruptive behavior symptoms associated with autistic disorder in children five to 17 years of age.13 Risperidone also improves inappropriate speech, lethargy/social withdrawal, and stereotypic behavior that often occur in children with autistic disorder.1 In adults with autistic disorder, risperidone decreases the incidence of T repetitive behavior, aggression, anxiety, and irritability, but high doses may be necessary.5

PRICE

Typical dosing of risperidone will cost approximately $125 (for the 0.25-mg tablets) or $137 (for the 0.5-mg tablets) per month. Haloperidol, which is also used to control behavior, will cost approximately $44 to $51 per month for the maximal dosage of 6 mg per day in children.

SIMPLICITY

The starting dosage of risperidone is 0.25 mg per day in children weighing less than 44 lb (20 kg), and 0.5 mg per day in persons weighing at least 44 lb.8 Depending on weight, doses may be titrated by 0.25 to 0.5 mg per day at two-week intervals, with targets of 0.5 and 1.0 mg per day. A suggested maximal dosage is approximately 1 to 3 mg per day, based on the weight of the patient.8 Patients should not mix risperidone oral solution with tea or cola because this combination can result in formation of a precipitate.11 Risperidone is also available as a rapidly disintegrating tablet that may be taken without water.

Bottom Line

Risperidone does not alter the course of autistic disorder, but is effective for controlling irritability and other associated symptoms. Patients taking risperidone should be appropriately monitored for adverse effects, especially abnormal movements. If extrapyramidal symptoms appear, therapy should be discontinued.8

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