Can I give Emeset (ondansetron) injection IV to a patient who is currently vomiting?

Administration of Ondansetron (Emeset) Injection for Active Vomiting

Yes, ondansetron (Emeset) injection can be safely administered intravenously to a patient who is actively vomiting, and is in fact the preferred treatment in this situation.

Rationale for IV Ondansetron in Active Vomiting

Ondansetron is a 5-HT3 receptor antagonist that effectively blocks serotonin receptors involved in the vomiting reflex. When a patient is actively vomiting:

• Oral medications are not feasible due to ongoing emesis
• IV administration provides rapid onset of action
• The FDA has approved ondansetron injection for the prevention and treatment of nausea and vomiting 1

Proper Administration Protocol

For a patient who is currently vomiting:

1. Dosage: Administer 8 mg IV ondansetron (standard adult dose) 1
2. Administration method: Dilute in 50 mL of 5% Dextrose Injection or 0.9% Sodium Chloride Injection 1
3. Infusion rate: Infuse over 15 minutes to minimize side effects 1
4. Timing: Administer immediately to control ongoing vomiting 2

Special Considerations

• Hepatic impairment: For patients with severe hepatic impairment (Child-Pugh score ≥10), reduce maximum daily dose to 8 mg 1
• Monitoring: Watch for potential side effects including headache and constipation 3
• Breakthrough vomiting: If vomiting persists despite initial ondansetron, consider adding:
  • A dopamine antagonist such as metoclopramide 2
  • A benzodiazepine such as lorazepam for added anxiolytic effect 2

Efficacy Evidence

Ondansetron has demonstrated high efficacy in treating acute vomiting:

• Intravenous ondansetron provides significant reduction in nausea scores (mean decrease of 4.0 on a 10-point scale) in emergency settings 4
• Complete control of vomiting has been achieved in up to 97.3% of patients with acute vomiting when using IV ondansetron 5
• Ondansetron is considered safe and effective for prehospital treatment of nausea and vomiting 4

Important Caveats

• Ensure adequate hydration and assess for electrolyte abnormalities in patients with prolonged vomiting 2
• Rule out other causes of vomiting that may require specific treatment (e.g., increased intracranial pressure, bowel obstruction) 3
• For refractory vomiting, consider adding a second agent from a different drug class rather than repeating ondansetron 2

Follow-up Management

After administering IV ondansetron:

• Monitor response for 15-30 minutes
• If vomiting resolves, consider maintenance therapy
• For patients with cyclical vomiting or chemotherapy-induced vomiting, prophylactic regimens may be needed for subsequent episodes 2

Ondansetron injection is highly effective for treating active vomiting and is considered a first-line agent in emergency settings due to its favorable safety profile and lack of sedating effects compared to other antiemetics 6.