RISPERIDONE
Clinical safety rating: safe
Animal studies have demonstrated safety
Risperidone is an atypical antipsychotic that antagonizes dopamine D2 receptors and serotonin 5-HT2A receptors. It also has moderate affinity for alpha1-adrenergic and H1-histaminergic receptors, and low affinity for muscarinic receptors.
| Metabolism | Extensively metabolized in the liver via CYP2D6 and CYP3A4 to 9-hydroxyrisperidone (paliperidone), which has similar pharmacological activity. The parent drug and metabolite are equally active. |
| Excretion | Renal (70% as metabolites, 14% as parent drug) and fecal (14%) |
| Half-life | Risperidone: 3 hours (CYP2D6 extensive metabolizers), 20 hours (poor metabolizers); active metabolite 9-hydroxyrisperidone: 21-30 hours; steady-state reached in 5-6 days |
| Protein binding | Risperidone: 90% bound to albumin and alpha-1-acid glycoprotein; 9-hydroxyrisperidone: 77% bound |
| Volume of Distribution | Risperidone: 1-2 L/kg; 9-hydroxyrisperidone: 0.5-1 L/kg; extensive tissue distribution |
| Bioavailability | Oral: 70% (tablet), 70% (oral solution); intramuscular: 100% for immediate-release, 28% for long-acting injection relative to oral |
| Onset of Action | Oral: 1-2 hours for antipsychotic effect, up to 1-2 weeks for full therapeutic response; intramuscular: 15-30 minutes for sedation, 1-2 weeks for antipsychotic effect |
| Duration of Action | Oral: 24 hours with once-daily dosing; intramuscular: 2 weeks for the long-acting formulation (Risperdal Consta) after steady state achieved |
| Molecular Weight | 410.48 |
| Action Class | Atypical Antipsychotic |
Initial 2 mg orally once daily, titrated to target dose of 4-6 mg orally once daily (or divided twice daily); maximum 16 mg/day. Alternatively, long-acting IM injection: 25 mg IM every 2 weeks.
| Dosage form | SOLUTION |
| Renal impairment | CrCl ≥30 mL/min: no adjustment. CrCl <30 mL/min: initiate at 0.5 mg orally twice daily for at least 1 week, then increase by 0.5 mg twice daily as tolerated; maximum 3 mg/day. |
| Liver impairment | Child-Pugh Class A or B: initiate at 0.5 mg orally twice daily, increase cautiously. Class C: avoid or use with extreme caution; no specific established dose. |
| Pediatric use | Adolescents (13-17 yr) with schizophrenia: initial 0.5 mg orally once daily, titrate to 3 mg/day as tolerated. Children (10-17 yr) with bipolar mania: initial 0.5 mg once daily, titrate to 1-2.5 mg/day. Weight-based not standard; use fixed dosing. |
| Geriatric use | Initiate at 0.5 mg orally once daily; increase by 0.5 mg/day increments; target dose 1-2 mg/day; monitor for orthostasis and extrapyramidal symptoms. |
| 1st trimester | Limited data; may be associated with increased risk of congenital malformations, particularly cardiac defects, although absolute risk is low. Use only if benefit outweighs risk. |
| 2nd trimester | Monitor for gestational diabetes, excessive weight gain, and extrapyramidal symptoms. Risk of preterm birth and low birth weight reported. Use considered if clearly needed. |
| 3rd trimester | Risk of neonatal extrapyramidal symptoms, agitation, feeding difficulties, and withdrawal syndrome upon delivery. Use only if clearly needed; taper before delivery if possible. |
Clinical note
Strong CYP2D6 inhibitors may increase levels Can cause hyperprolactinemia and metabolic changes.
| Placental transfer | Risperidone crosses the placenta. Cord blood levels are approximately 25-50% of maternal plasma levels. Active metabolite 9-hydroxyrisperidone also crosses. |
| Breastfeeding | Risperidone and its active metabolite 9-hydroxyrisperidone are excreted into breast milk in low to moderate amounts. Relative infant dose is approximately 4-10% of maternal weight-adjusted dose. Monitor infant for drowsiness, irritability, poor feeding, and abnormal movements. Generally considered compatible with breastfeeding, but benefit of therapy and risks to infant should be considered. |
■ FDA Black Box Warning
Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Risperidone is not approved for the treatment of dementia-related psychosis.
| Common Effects | bipolar disorder |
| Serious Effects | Neuroleptic Malignant Syndrome (NMS), Tardive Dyskinesia, Hyperglycemia and Diabetes Mellitus, Hyperprolactinemia, QT Prolongation, Orthostatic Hypotension, Seizures, Leukopenia, Neutropenia, and Agranulocytosis, Cerebrovascular Adverse Events in Elderly Patients with Dementia-Related Psychosis, Increased Mortality in Elderly Patients with Dementia-Related Psychosis |
Hypersensitivity to risperidone or any excipients
| Precautions | Increased mortality in elderly patients with dementia-related psychosis, Cerebrovascular adverse events (stroke, TIA) in elderly with dementia, Neuroleptic malignant syndrome (NMS), Tardive dyskinesia, Hyperglycemia and diabetes mellitus, Weight gain, Hyperprolactinemia, Orthostatic hypotension, Seizures, Leukopenia/neutropenia/agranulocytosis, QT interval prolongation, Priapism, Dysphagia, Body temperature dysregulation, Potential for cognitive and motor impairment |
Loading safety data…
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Risperidone is not a major teratogen in humans based on available studies, but there is a slight increase in risk for gestational diabetes and preterm birth. Third-trimester exposure may cause neonatal extrapyramidal symptoms (e.g., agitation, hypertonia, tremors) and withdrawal symptoms (e.g., respiratory distress, feeding difficulties). |
| Fetal Monitoring | For pregnant women: monitor for gestational diabetes, excessive weight gain, and signs of preeclampsia. For neonates: monitor for extrapyramidal symptoms (e.g., dystonia, rigidity), withdrawal, and respiratory depression. Consider therapeutic drug monitoring (TDM) during pregnancy as levels may decrease. |
| Fertility Effects | Risperidone can increase prolactin levels, leading to menstrual irregularities, galactorrhea, and possible ovulatory dysfunction in females, potentially reducing fertility. In males, hyperprolactinemia may cause decreased libido and erectile dysfunction. Effects are reversible upon dose reduction or discontinuation. |
| Food/Dietary | Avoid grapefruit and grapefruit juice; may increase risperidone plasma concentrations. Alcohol can potentiate CNS depression and increase risk of side effects. No specific food restrictions; take with or without food. High-fat meals may slightly increase absorption. |
| Clinical Pearls | Monitor for orthostatic hypotension, especially during dose titration. Risperidone can cause QTc prolongation; obtain baseline ECG in at-risk patients. Extrapyramidal symptoms (EPS) are dose-dependent; use lowest effective dose. In elderly dementia patients, increased risk of cerebrovascular events; not approved for this indication. Prolactin elevation is common; monitor for gynecomastia, galactorrhea, and sexual dysfunction. Taper slowly to avoid withdrawal dyskinesia. |
| Patient Advice | Take risperidone exactly as prescribed; do not stop suddenly without consulting your doctor. · Avoid alcohol and grapefruit juice as they may affect drug levels and increase side effects. · Rise slowly from sitting or lying down to prevent dizziness from low blood pressure. · Report any involuntary muscle movements, restlessness, or stiffness to your healthcare provider. · Notify your doctor if you experience breast swelling, discharge, or sexual problems. · Do not drive or operate heavy machinery until you know how risperidone affects you. |