Management of Risperidone Overdose
Risperidone overdose primarily causes drowsiness, sedation, tachycardia, hypotension, and extrapyramidal symptoms, requiring supportive care with close monitoring as there is no specific antidote. 1
Clinical Manifestations of Risperidone Overdose
Common Symptoms
- Central nervous system effects:
- Drowsiness and sedation (most common)
- Lethargy
- Altered consciousness
- Cardiovascular effects:
- Tachycardia (common)
- Hypotension
- QT prolongation (in some cases)
- Neurological effects:
- Extrapyramidal symptoms (EPS)
- Dystonic reactions
- Muscle spasms
- Tremors
Severity Based on Studies
- In a study of 107 patients with risperidone overdose, tachycardia (58%) and dystonic reactions (11%) were the main features, with minimal cardiac toxicity and no deaths 2
- Pediatric patients may be particularly susceptible to EPS even at relatively low doses 3
Management Algorithm
1. Initial Assessment and Stabilization
- Ensure adequate airway, breathing, and circulation
- Obtain vital signs with special attention to:
- Blood pressure (monitor for hypotension)
- Heart rate (monitor for tachycardia)
- Respiratory rate
- Temperature (monitor for hyperthermia)
2. Decontamination
- For recent ingestions (<1 hour):
- Consider activated charcoal with sorbitol
- Gastric lavage may be considered in massive ingestions
3. Cardiac Monitoring
- Obtain ECG to assess for:
- QT prolongation
- QRS widening
- Dysrhythmias
- Continuous cardiac monitoring for at least 6 hours post-ingestion
4. Management of Specific Complications
Extrapyramidal Symptoms
- Administer diphenhydramine:
- Adults: 25-50 mg IV/IM
- Children: 1-2 mg/kg IV/IM (maximum 50 mg)
- May repeat every 30 minutes until symptoms resolve
Hypotension
- IV fluid bolus with normal saline
- If refractory, consider vasopressors
QT Prolongation
- Correct electrolyte abnormalities (particularly potassium and magnesium)
- Avoid other QT-prolonging medications
- Consider cardiology consultation for significant prolongation
Seizures
- Benzodiazepines (lorazepam 2-4 mg IV in adults)
- If seizures persist, consider standard anticonvulsant therapy
5. Laboratory Studies
- Complete blood count
- Comprehensive metabolic panel
- Serum electrolytes (particularly sodium and potassium)
- Liver and renal function tests
- Toxicology screen (to rule out co-ingestions)
6. Disposition
- Patients with significant symptoms require admission for observation
- Asymptomatic patients should be observed for at least 6 hours
- Most symptoms resolve within 24 hours, with all patients typically asymptomatic by 72 hours post-ingestion 4
Special Considerations
Pediatric Patients
- Children are more susceptible to EPS at lower doses
- Dystonic reactions may respond well to diphenhydramine 3
- Careful weight-based dosing of all medications
Co-ingestions
- Co-ingestion with other psychiatric medications may worsen toxicity
- Particular caution with:
- SSRIs (especially paroxetine, which has been associated with Torsade de pointes when combined with risperidone) 1
- Tricyclic antidepressants
- Other antipsychotics
Pitfalls and Caveats
No specific antidote exists for risperidone overdose - treatment is supportive 1
Underestimating pediatric sensitivity - Children may develop significant EPS at doses that would be therapeutic in adults 3
Failing to monitor for delayed effects - While most symptoms appear early, continued monitoring is necessary as some effects may be delayed
Missing co-ingestions - Many overdoses involve multiple substances, which can complicate the clinical picture
Premature discharge - Patients should be observed until symptoms have clearly resolved, which may take up to 24-72 hours in severe cases 4
The prognosis for isolated risperidone overdose is generally good, with most patients experiencing complete resolution of symptoms within 24-72 hours with appropriate supportive care 4, 2.