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Risperidone
Risperidone is a second-generation (atypical) antipsychotic1 used to treat schizophrenia,2 bipolar mania,2 and irritability associated with autism.2 It can cause sedation,3 and long-acting injectable forms last for several weeks.4 Common adverse effects include weight gain5 and drowsiness.6 Serious adverse effects can include potentially permanent involuntary movements (tardive dyskinesia), neuroleptic malignant syndrome7, and high blood sugar3. It may increase the risk of death in older people with dementia-related psychosis.
Dosage & Duration
Dosage
Doses are population estimates that vary widely between individuals.
Duration
Subjective Effects
Pharmacology
Pharmacodynamics
Risperidone antagonizes dopamine D2 and serotonin 5-HT2A receptors, reducing dopaminergic and serotonergic signaling in the brain, although its precise therapeutic mechanism is not fully understood. Its affinity for 5-HT2A is approximately 10-20 times greater than for D2, and its D2 binding is described as transient, with rapid dissociation. It also antagonizes other dopamine and serotonin receptor subtypes, alpha-adrenergic receptors, and histamine H1 receptors. Risperidone inhibits D-amino acid oxidase, reducing the breakdown of D-amino acids, and inhibits voltage-gated sodium channels at clinically used concentrations through accumulation in synaptic vesicles.
Pharmacokinetics
Risperidone is well absorbed orally, with an absolute bioavailability of 70% (coefficient of variation 25%).2 It undergoes extensive hepatic metabolism, primarily through CYP2D6-mediated hydroxylation to an active metabolite with approximately the same receptor-binding affinity as the parent drug; N-dealkylation is a smaller pathway. Genetic variation in CYP2D6 affects metabolism, with an elimination half-life of 3 hours in extensive metabolizers and up to 20 hours in poor metabolizers. Risperidone is also listed as a substrate of CYP3A4, CYP3A5, CYP3A7, and P-glycoprotein, and as a weak CYP2D6 inhibitor. Its volume of distribution is approximately 1-2 L/kg.8 In human plasma, risperidone and its active metabolite are approximately 88% and 77% protein-bound, respectively, binding to albumin and alpha-1-acid glycoprotein. Elimination involves renal excretion; clearance is reduced in older people, with longer elimination half-lives for both the parent drug and its active metabolite. Clearance is approximately 60% lower in people with creatinine clearance of 15-59 mL/min.
Interactions
An unlisted combination is an unknown one, not a safe one. Check a dedicated combination chart before mixing.
Tolerance
Harm Potential
Toxicity
Risperidone treatment is associated with increased mortality in older people with dementia-related psychosis.
LD50 Data
| Species | Route | Value |
|---|---|---|
| Rat | Oral | 57.7 mg/kg |
| Rat | Intravenous | 34 mg/kg |
Risperidone commonly causes movement problems10 and can cause potentially permanent tardive dyskinesia; overdose can produce dystonia or muscle spasms.
Risperidone can cause hypotension2, while overdose can produce tachycardia or bradycardia.
Risperidone commonly causes weight gain5 and can cause high blood sugar.
Risperidone commonly elevates prolactin and can cause sexual side effects, galactorrhea, infertility, and gynecomastia.
Chronic risperidone use can reduce bone mineral density and lead to fractures.
Risperidone commonly causes dry mouth and constipation.2
Seizure Risk
Risperidone can lower the seizure threshold, and seizures can occur during overdose.
History & Culture
Early research and development
Research on risperidone began in the late 1980s. Its development drew on the molecular structures of benperidol and ketanserin.
Legality
By Country
United StatesPrescription only
AustraliaPrescription only
CanadaPrescription only
GermanyPrescription only
SwitzerlandPrescription only
United KingdomPrescription onlyReferences
Citations
Article Status
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