Isipredon (Risperidone)

Risperidone is used to manage psychotic and mood disorders by modulating dopamine and serotonin pathways.

• Schizophrenia: reduces positive and negative symptoms, improving overall functioning.
• Bipolar I disorder: helps control manic episodes and stabilizes mood.
• Irritability associated with autistic disorder: lessens aggression and temper outbursts in children and adolescents.
• Schizoaffective disorder: alleviates psychotic symptoms and stabilizes mood when used as adjunct therapy.
• Maintenance therapy in schizophrenia: maintains symptom control and reduces relapse risk.
• Acute agitation in schizophrenia: provides rapid calming effect when administered orally.

• Risperidone exerts its antipsychotic activity by antagonizing dopamine D2 receptors and serotonin 5‑HT2A receptors in the central nervous system. This dual blockade reduces dopaminergic hyperactivity linked to psychosis while modulating serotonergic transmission that influences mood, cognition and behavior. The drug also shows moderate affinity for α1‑adrenergic, histamine H1 and serotonin 5‑HT7 receptors, contributing to its overall pharmacodynamic profile.

Risperidone may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Drowsiness
• Weight gain
• Dry mouth
• Constipation

Serious or Rare Side Effects

• Extrapyramidal symptoms (tremor, rigidity)
• Neuroleptic malignant syndrome
• Elevated prolactin levels (galactorrhea, menstrual changes)

When prescribing risperidone, clinicians should consider several safety precautions to minimise risks.

• Assess psychiatric history: confirm diagnosis and evaluate previous antipsychotic response.
• Monitor metabolic parameters: check weight, glucose and lipid levels regularly.
• Evaluate cardiovascular status: watch for orthostatic hypotension and ECG changes.
• Observe for movement disorders: screen for early signs of extrapyramidal symptoms.
• Pregnancy and lactation: use only if benefits outweigh potential risks (Category B1).
• Store at ambient temperature: keep below 25 °C in the original container, protect from moisture.

Risperidone can interact with other medicines, altering its effectiveness or safety profile.

Major Interactions (Avoid)

• Strong CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): may increase risperidone plasma levels.
• CNS depressants (e.g., benzodiazepines, opioids): can enhance sedation and respiratory depression.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., carbamazepine, phenytoin): may reduce risperidone concentrations.
• Antihypertensive agents: additive hypotensive effect.
• Anticholinergic drugs: may mask extrapyramidal symptoms.
• Lithium: combined use may increase risk of neurotoxicity.