Risperidone

1. Introduction

Risperidone is an atypical antipsychotic medication used to treat schizophrenia, bipolar disorder, and irritability associated with autism spectrum disorder (ASD). It works by modulating dopamine (D2) and serotonin (5-HT2A) receptors in the brain, helping to alleviate psychotic symptoms, mood instability, and behavioural disturbances.

2. Indications

  • Schizophrenia (adults and adolescents ≥13 years)
  • Bipolar disorder (manic or mixed episodes; adults and children ≥10 years)
  • Irritability associated with autism spectrum disorder (children and adolescents 5–16 years)

3. Dosage

Adults:

  • Schizophrenia: Start with 1 mg twice daily; increase by 1–2 mg daily until the target dose of 4–8 mg/day is reached. Maximum dose: 16 mg/day.
  • Bipolar disorder (manic or mixed episodes): Start with 2–3 mg once daily; titrate up to 6 mg/day if needed.
  • Long-acting injection (Risperdal Consta): Start with 25 mg intramuscularly every 2 weeks. Adjust to 37.5–50 mg every 2 weeks if required.

Elderly or Debilitated Patients:

  • Start at 0.5 mg twice daily; titrate gradually as tolerated.

Children:

  • Schizophrenia (≥13 years): Start with 0.5 mg once daily; increase to 3 mg/day if needed. Maximum dose: 6 mg/day.
  • Bipolar disorder (≥10 years): Start with 0.5 mg once daily; titrate up to 2.5 mg/day.
  • Autism-associated irritability (5–16 years): Start with 0.25 mg once daily (≤20 kg) or 0.5 mg once daily (>20 kg); titrate to a maximum dose of 1–2.5 mg/day based on weight.

4. Administration

  • Oral tablets and liquid forms can be taken with or without food.
  • Orally disintegrating tablets should be placed on the tongue to dissolve.
  • Long-acting injections should only be administered by healthcare professionals.

5. Forms Available

  • Tablets: 0.25 mg, 0.5 mg, 1 mg, 2 mg, 3 mg, 4 mg, 6 mg
  • Orally disintegrating tablets: 0.5 mg, 1 mg, 2 mg, 3 mg, 4 mg
  • Oral solution: 1 mg/mL
  • Long-acting injection: 25 mg, 37.5 mg, 50 mg

6. Side Effects

6.1 Common Side Effects:

  • Drowsiness or sedation
  • Weight gain
  • Increased appetite
  • Fatigue
  • Dizziness

6.2 Less Common Side Effects:

  • Increased prolactin levels (hyperprolactinaemia)
  • Constipation
  • Dry mouth
  • Restlessness (akathisia)

6.3 Rare but Serious Side Effects:

  • Tardive dyskinesia (involuntary movements)
  • Neuroleptic malignant syndrome (NMS)
  • Severe allergic reactions (e.g., anaphylaxis)
  • Extrapyramidal symptoms (e.g., tremors, muscle rigidity)
  • QT prolongation (heart rhythm changes)

7. Warnings

  • Elderly with Dementia: Increased risk of mortality in elderly patients with dementia-related psychosis; risperidone is not approved for this use.
  • Neuroleptic Malignant Syndrome (NMS): Discontinue immediately if symptoms like high fever, muscle stiffness, or confusion occur.
  • Tardive Dyskinesia: Long-term use may lead to irreversible involuntary movements.
  • Hyperglycaemia and Diabetes: Monitor blood glucose in patients at risk of metabolic complications.

8. Precautions

  • Use cautiously in patients with a history of seizures, cardiovascular disease, or electrolyte imbalances.
  • Monitor weight, lipid profile, and blood glucose levels in long-term use.
  • Avoid abrupt discontinuation to minimise withdrawal effects or symptom relapse.

9. Interactions

  • CNS depressants (e.g., opioids, alcohol): Enhanced sedation and respiratory depression.
  • CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): Increased risperidone plasma levels; monitor for side effects.
  • Antihypertensives: May enhance the blood pressure-lowering effect, causing dizziness or hypotension.
  • QT-prolonging drugs (e.g., amiodarone): Increased risk of arrhythmias.

10. Monitoring Parameters

  • Monitor for symptom improvement (e.g., reduction in psychotic or manic episodes).
  • Assess for weight gain, hyperglycaemia, and metabolic changes periodically.
  • Observe for signs of extrapyramidal symptoms or tardive dyskinesia.
  • Measure prolactin levels if symptoms of hyperprolactinaemia occur (e.g., breast tenderness, galactorrhoea).

11. Use in Children

  • Approved for schizophrenia (≥13 years), bipolar disorder (≥10 years), and autism-related irritability (5–16 years).
  • Monitor for weight gain, metabolic changes, and sedation in paediatric use.

12. Use in Pregnancy

  • Category C: Use only if the potential benefits outweigh the risks. Neonates exposed in the third trimester may experience withdrawal symptoms or extrapyramidal effects.

13. Use in Elderly

  • Use cautiously in elderly patients due to an increased risk of falls, sedation, and metabolic effects.
  • Avoid in dementia-related psychosis due to a higher risk of stroke and death.

14. Use in Kidney Disease

  • Reduce dose in patients with moderate to severe renal impairment.
  • Start with 0.5 mg twice daily and titrate slowly.

15. Use in Liver Disease

  • Use cautiously in patients with hepatic impairment; initiate at 0.5 mg twice daily and adjust as needed.

16. Patient Counselling Points

  • Take risperidone as prescribed, and do not stop taking it without consulting your doctor.
  • Avoid alcohol while using this medication, as it may enhance sedation.
  • Report any unusual movements, severe muscle stiffness, or fever to your doctor immediately.
  • Inform your doctor if you experience excessive weight gain or signs of high blood sugar (e.g., increased thirst, frequent urination).
  • Orally disintegrating tablets dissolve on the tongue and do not require water.

17. Table of Brand Names, Manufacturer, and Prices in USD

Brand NameManufacturerStrength/Dosage FormPrice (USD)
RisperdalJanssen2 mg Tablet$120 (30 tablets)
Risperdal ConstaJanssen25 mg Injection$500 (1 dose)
Generic RisperidoneVarious2 mg Tablet$10 (30 tablets)

18. 15 FAQs (Frequently Asked Questions)

1. What is Risperidone used for?
Risperidone is used to treat schizophrenia, bipolar disorder, and autism-related irritability.

2. How does Risperidone work?
It blocks dopamine and serotonin receptors, reducing psychotic symptoms and mood instability.

3. Can Risperidone cause weight gain?
Yes, weight gain is a common side effect, particularly in long-term use.

4. Is Risperidone safe for children?
Yes, it is approved for certain conditions in children aged 5 years and older.

5. Can Risperidone cause drowsiness?
Yes, drowsiness or sedation is a common side effect.

6. Can Risperidone cause diabetes?
It may increase the risk of hyperglycaemia and diabetes in some patients.

7. Can Risperidone cause extrapyramidal symptoms?
Yes, symptoms like tremors or muscle stiffness may occur, especially at higher doses.

8. Can Risperidone be used during pregnancy?
It should only be used if the benefits outweigh the risks. Consult your doctor.

9. How long does Risperidone take to work?
Improvement in symptoms may be noticed within a few days, but full effects can take weeks.

10. Is Risperidone addictive?
No, risperidone is not considered addictive.

11. Can I drink alcohol while taking Risperidone?
No, alcohol can enhance sedation and other side effects.

12. Does Risperidone require regular monitoring?
Yes, weight, glucose levels, and signs of movement disorders should be monitored regularly.

13. Can Risperidone cause high prolactin levels?
Yes, it may cause hyperprolactinaemia, leading to symptoms like breast enlargement