Risperidone

Class & Mechanism

Risperidone is a second-generation (atypical) antipsychotic. It works primarily through dopamine D2 receptor blockade and serotonin 5-HT2A receptor antagonism. The 5-HT2A blockade reduces the risk of extrapyramidal side effects (EPS) compared to typical antipsychotics, particularly at lower doses.

Indications

• First-line treatment for acute psychosis in schizophrenia and related disorders.
• First-line pharmacological treatment for the delusional type of morbid-jealousy.
• Maintenance therapy in schizophrenia.
• Available as a long-acting injectable (LAI) formulation for patients with poor adherence.

Dosage

• Typical daily dose: 2–6 mg.
• Start at the lower end of the licensed dose range and titrate according to response and tolerability.

Side Effects

• EPS — risk increases at higher doses. Can cause acute dystonia, parkinsonism, and akathisia.
• Hyperprolactinaemia — more common with risperidone than other atypicals. Can cause galactorrhoea, gynaecomastia, and sexual dysfunction.
• Weight gain and metabolic effects — less than olanzapine and clozapine, but still significant.
• Sedation — less sedating than olanzapine or quetiapine.

Monitoring

• Baseline body mass index (BMI), blood pressure (BP), fasting blood sugar (FBS), and lipids before starting.
• Regular monitoring of weight, metabolic parameters, and EPS (using the Abnormal Involuntary Movement Scale [AIMS]).

📝 TODO: Needs source — specific monitoring protocols, interaction profile, contraindications.

Sri Lanka Availability

• Available in government hospitals in Sri Lanka as one of the most widely used atypical antipsychotics.

Exam Focus

Viva Questions

• Why is risperidone preferred as a first-line atypical? (Widely used, good efficacy, available in oral and LAI forms.)
• What are the key side effects? (EPS at higher doses, hyperprolactinaemia.)

MCQ Traps

• ⚠️ EXAM DETAIL: EPS risk with risperidone is dose-dependent — low doses have low EPS risk, but high doses approach typical antipsychotic EPS rates.
• ⚠️ EXAM DETAIL: Hyperprolactinaemia is more common with risperidone than with other atypicals like olanzapine or aripiprazole.

Source Notes

• Information in this page is drawn from management discussions in schizophrenia, delusional-disorder, and morbid-jealousy, which are sourced from the Handbook of Clinical Psychiatry (de Silva & Hanwella), the Shorter Oxford Textbook of Psychiatry, and Dr. Ajith Jayasekara’s lectures.