Risperidone – Uses, Effects & Side Effects

What is Risperidone?

Risperidone is an atypical antipsychotic (second-generation antipsychotic) widely used in psychiatry. It belongs to the class of benzisoxazole derivatives and was developed in the early 1990s. Risperidone is available in multiple formulations, including oral tablets, orally disintegrating tablets, oral solution, and long-acting injectable depot formulations for extended release.

Indications

Risperidone is approved and used for the following conditions:

• Schizophrenia: Treatment of acute psychotic episodes and long-term maintenance therapy to prevent relapse
• Bipolar disorder: Management of manic episodes associated with bipolar I disorder
• Irritability associated with autism spectrum disorder (ASD): Approved for use in children and adolescents
• Short-term treatment of aggression and behavioral disturbances in elderly patients with dementia (with careful risk-benefit assessment)

Mechanism of Action

Risperidone acts as a dopamine D2 receptor antagonist and a serotonin 5-HT2A receptor antagonist. The dual blockade of these receptors is central to its therapeutic effects:

• Blockade of D2 receptors in the mesolimbic pathway reduces positive symptoms of schizophrenia, such as hallucinations and delusions.
• Blockade of 5-HT2A receptors helps improve negative symptoms (e.g., social withdrawal, lack of motivation) and reduces the risk of extrapyramidal side effects compared to older, first-generation antipsychotics.

Risperidone also affects alpha-1 adrenergic and histamine H1 receptors, which can contribute to certain side effects such as low blood pressure or sedation.

Dosage

The dosage of risperidone depends on the indication, patient age, and individual response. Typical dosage ranges include:

• Schizophrenia (adults): 2–8 mg per day, usually divided into two doses
• Manic episodes (adults): 2–6 mg per day
• Children and adolescents (ASD, behavioral disorders): Significantly lower doses, individually adjusted

Dose adjustments are required in patients with renal or hepatic impairment and in elderly patients. Dosage must always be determined and monitored by a qualified healthcare professional.

Side Effects

Like all antipsychotic medications, risperidone can cause side effects. Common and clinically relevant side effects include:

• Extrapyramidal symptoms (EPS): Movement disorders such as tremor, muscle rigidity, or involuntary movements (tardive dyskinesia)
• Weight gain and metabolic changes (elevated blood lipids, increased blood glucose)
• Elevated prolactin levels: May lead to menstrual irregularities, gynecomastia (breast enlargement in males), or galactorrhea (milk discharge)
• Sedation and drowsiness
• Orthostatic hypotension: A drop in blood pressure when standing up
• Sexual dysfunction
• Rare but serious: Neuroleptic malignant syndrome (high fever, severe muscle rigidity, altered consciousness – a medical emergency)

Contraindications and Drug Interactions

Risperidone is contraindicated in patients with known hypersensitivity to the active substance. Special caution is required in:

• Patients with cardiac conditions (possible QT interval prolongation)
• Patients with Parkinson's disease (symptoms may worsen)
• Elderly patients with dementia (increased risk of stroke)

Important drug interactions exist with other centrally acting substances, antihypertensive medications, and drugs that prolong the QT interval. Alcohol should be avoided during treatment.

Important Notes on Use

Risperidone can be taken with or without food. The medication must not be discontinued without medical consultation, as abrupt discontinuation may lead to withdrawal symptoms or relapse. Pregnant or breastfeeding individuals should only use risperidone after careful medical evaluation.

References

1. European Medicines Agency (EMA): Summary of Product Characteristics – Risperidone. www.ema.europa.eu
2. Leucht S, Corves C, Arbter D, et al. – Second-generation versus first-generation antipsychotic drugs for schizophrenia: a meta-analysis. The Lancet. 2009;373(9657):31-41.
3. American Psychiatric Association (APA): Practice Guideline for the Treatment of Patients with Schizophrenia, 3rd Edition, 2021.