【藥品性質提示】 根據 2019 AGS Beers Criteria，本藥品為【潛在不適當用藥 (PIM)】，不建議用於老年人 (除非用於思覺失調、雙極症、或化療止吐)。

思覺失調症
1. Schizophrenia
2. Acute mania or mixed episodes associated with bipolar I disorder (as monotherapy in children or adults, or in combination with lithium or valproate in adults)
3. Irritability/aggression associated with autistic disorder

Risperidone is a potent 5-HT2 antagonist with D2 antagonism. Whereas typical antipsychotics are dopamine antagonists, the additional serotonin antagonism increases efficacy for negative symptoms of schizophrenia and reduces the likelihood of EPS.

Distribution:
1. Oral bioavailability: 70%
2. Plasma protein binding: Risperidone 90%; 9-hydroxyrisperidone 77%
Metabolism:
Extensively hepatic via CYP2D6 to 9-hydroxyrisperidone (similar pharmacological activity as risperidone)
Elimination Half-life:
Risperidone 3 hrs; its active metabolites: 24 h

Hypersensitivity to risperidone or any component of the formulation

C

Enters breast milk/not recommended

Somnolence, fatigue, headache, fever, dystonia, anxiety, extrapyramidal symptoms, dizziness, dry mouth, constipation, weight gain, urinary incontinence, tremor, rhinitis, cough.

Schizophrenia and bipolar disorder:
(PO) 1 mg BID initially, increasing by 1 mg/day every 24 h to the usual effective dosage of 4-6 mg/day
Irritability associated with autistic disorder:
(PO) 0.25mg for patients< 20 kg and 0.5 mg for patients> 20 kg. Dose can be increased by 0.25 or 0.5 mg at 2 week intervals to a target dose of 0.5-3 mg/day.