Ruixintuo Risperidone Microspheres for Injection (II)

1. Indications and Usage
Schizophrenia Spectrum Disorders:
Treatment of acute and chronic schizophrenia and other psychotic states.
Symptom Management:
Effective in managing prominent positive symptoms (e.g., hallucinations, delusions, thought disorder), negative symptoms (e.g., emotional withdrawal, retardation), and associated emotional symptoms (e.g., depression, anxiety, guilt).
2. Dosage and Administration
Route of Administration:
For Deep Intramuscular (IM) Injection ONLY. Intravenous administration is strictly contraindicated.
Recommended Dosage:
Initial Dose: Typically 25 mg, administered once every 2 weeks.
Titration: Dosage may be increased or decreased in 25 mg increments based on clinical response and tolerability.
Maximum Dose: Usually not exceed 50 mg every 2 weeks.
Critical Administration Instructions:
Reconstitution: Must be reconstituted with the provided vehicle/suspension immediately before use. Gently shake to form a uniform suspension.
Injection Site: Administer into the deep gluteal muscle. Rotate injection sites between the left and right buttocks.
Oral Overlap: Patients must continue their existing oral antipsychotic medication for at least the first 3 weeks after the initial injection to maintain therapeutic drug levels.
3. Mechanism of Action
Receptor Antagonism:
Risperidone acts as a potent antagonist at serotonin 5-HT2A receptors and dopamine D2 receptors.
Therapeutic Effect:
By blocking these neurotransmitter receptors, it alleviates the positive and negative symptoms of schizophrenia. The microsphere formulation ensures slow, sustained release of the drug into the systemic circulation over a 2-week period.
4. Safety and Warnings
Hyperprolactinemia:
Risperidone elevates prolactin levels, potentially causing galactorrhea, gynecomastia, menstruation disorders, and amenorrhea.
Extrapyramidal Symptoms (EPS):
Includes muscle stiffness, tremor, rigidity, akinesia, and akathisia. The risk is dose-dependent.
Metabolic Changes:
May cause weight gain, hyperglycemia, and dyslipidemia. Regular monitoring of blood glucose and lipid profiles is required.
Neuroleptic Malignant Syndrome (NMS):
A rare but fatal syndrome characterized by high fever, muscle rigidity, altered consciousness, and elevated creatine phosphokinase.
Tardive Dyskinesia:
A potentially irreversible movement disorder that may occur with long-term use.
5. Adverse Reactions and Clinical Research
Most Common Adverse Reactions:
Insomnia, anxiety, agitation, memory impairment, headache, dizziness, dry mouth, visual changes, constipation, nausea, vomiting, and abdominal pain.
Clinical Research Highlights:
Phase 3 clinical trials have demonstrated that Risperidone Microspheres (II) provide significant and sustained improvement in schizophrenia symptoms with a favorable long-term safety profile compared to placebo.
6. Drug Interactions
CYP2D6 Inhibitors:
Concomitant use with strong CYP2D6 inhibitors (e.g., paroxetine, fluoxetine) may increase risperidone exposure and the risk of adverse effects.
Antihypertensives:
May enhance the hypotensive effect of antihypertensive drugs due to alpha-adrenergic blockade.
CNS Depressants:
Concomitant use with alcohol or other CNS depressants may increase sedation.
7. Pharmaceutical Information
Chemical Composition:
Active Ingredient: Risperidone.
Excipients: Poly(lactic-co-glycolic acid) (PLGA) microspheres.
Appearance: White to off-white powder prior to reconstitution; forms a milky white suspension after mixing with the vehicle.
Packaging: Single-use vial.
Storage: Store in the original carton at 2°C to 8°C. Do not freeze.