From the Guidelines
For a geriatric patient experiencing nausea and vomiting despite being on ondansetron (Zofran), I recommend adding a different antiemetic with a complementary mechanism of action, such as metoclopramide 5 mg orally or IV every 6-8 hours, to target different antiemetic pathways and potentially provide better symptom control. When considering additional antiemetics, it's essential to evaluate the patient's overall clinical context, including potential underlying causes of nausea and vomiting, such as constipation, gastroparesis, or other gastrointestinal disorders 1.
Key Considerations
- Ensure adequate hydration and consider IV fluids if the patient shows signs of dehydration
- Use caution with metoclopramide in geriatric patients due to increased risk of extrapyramidal symptoms; limit use to 5 days if possible
- Consider alternative agents, such as prochlorperazine or olanzapine, if metoclopramide is not suitable
- Evaluate the patient's medication regimen for potential contributors to nausea and vomiting, and adjust as needed
Additional Interventions
- Consider GI consultation for further evaluation if symptoms persist despite initial interventions
- Assess for potential electrolyte abnormalities and correct as needed
- Consider antacid therapy, such as proton pump inhibitors or H2 blockers, if the patient experiences heartburn or gastroesophageal reflux symptoms 1
Mechanism of Action
The recommended antiemetics target different pathways, including:
- Ondansetron: serotonin receptors
- Metoclopramide: dopamine receptors and gastric emptying enhancement
- Prochlorperazine: dopamine receptors
- Olanzapine: multiple mechanisms, including dopamine and serotonin receptor antagonism
By combining antiemetics with complementary mechanisms of action, healthcare providers can potentially improve symptom control and reduce the burden of nausea and vomiting in geriatric patients 1.
From the Research
Evaluation of Nausea and Vomiting
- A thorough history and physical examination are essential to determine the severity of symptoms and clues to their underlying etiology 2
- The evaluation should consider associated symptoms, timing of onset and duration of symptoms, exacerbating or relieving factors, alarm symptoms, medication and substance use, relationship with recent food ingestion, and comorbidities 3
Treatment Options
- Antiemetic therapy should be guided by the likely aetiology, although in practice, the clinical picture is often complex, and so regular reassessment is essential for adequate symptom control 4
- Nonpharmacologic management options include fluid and electrolyte replacement; small, frequent meals; and avoidance of trigger foods 3
- Pharmacologic therapy should be used for the shortest time necessary to control symptoms 3
- If symptoms are refractory despite adequate dosage and around-the-clock prophylactic administration, an empirical trial combining several therapies to block multiple emetic pathways should be attempted 2
Alternative Antiemetic Agents
- Metoclopramide and ondansetron have been compared in several studies, with similar effectiveness in reducing nausea and vomiting 5, 6
- However, metoclopramide may have a higher incidence of side effects such as drowsiness and anxiety 6
- The choice of antiemetic agent may depend on the individual patient's needs and medical history 6