What is the typical dosing of Metoclopramide (Reglan) for a patient with intractable nausea and vomiting due to gastroparesis?

Metoclopramide Dosing for Intractable Nausea and Vomiting in Gastroparesis

For patients with intractable nausea and vomiting due to gastroparesis, the recommended dosing of metoclopramide is 5-10 mg orally four times daily, 30 minutes before meals and at bedtime. 1

Initial Dosing Considerations

• For mild to moderate symptoms:

  • Start with oral metoclopramide 5-10 mg PO QID, 30 minutes before meals and at bedtime 1
  • Maximum recommended daily dose: 40 mg

• For severe or intractable symptoms:

  • Consider initiating therapy with injectable metoclopramide (IM or IV) 2
  • IV doses should be administered slowly over 1-2 minutes
  • Once symptoms begin to subside (may take up to 10 days), transition to oral therapy 2

Dosing Adjustments

• Renal impairment: For patients with creatinine clearance <40 mL/min, start at approximately half the recommended dose 2
• Hepatic impairment: No specific dose adjustment needed for patients with advanced liver disease if renal function is normal 2

Duration of Treatment

• FDA limits metoclopramide use to ≤12 weeks due to risk of tardive dyskinesia 3
• This limitation is important as the risk of tardive dyskinesia is approximately 0.1% per 1000 patient-years 3

Monitoring and Side Effects

• Monitor closely for:

  • Extrapyramidal symptoms (acute dystonia, parkinsonism)
  • Tardive dyskinesia (higher risk in elderly patients)
  • QT prolongation
  • Somnolence and depression 3

• If acute dystonic reactions occur:

  • Administer diphenhydramine 50 mg IM; symptoms usually subside 2

Alternative Options for Refractory Cases

When metoclopramide fails or is contraindicated, consider:

1. 5-HT3 receptor antagonists:

   • Ondansetron 4-8 mg BID or TID
   • Granisetron 1 mg BID or transdermal patch 1

2. Phenothiazine antipsychotics:

   • Prochlorperazine 5-10 mg QID
   • Chlorpromazine 10-25 mg TID or QID 1

3. Other antiemetics:

   • Meclizine 12.5-25 mg TID
   • Scopolamine 1.5 mg patch every 3 days 1

4. For continuous symptoms:

   • Consider continuous intravenous or subcutaneous infusions of different antiemetics 1

Special Considerations

• Diabetic patients: Optimize glycemic control first, as hyperglycemia can further delay gastric emptying 3
• Medication review: Discontinue any unnecessary medications that may worsen gastroparesis (opioids, anticholinergics, GLP-1 receptor agonists) 3
• Domperidone: May be considered for patients who cannot tolerate metoclopramide, but requires FDA investigational drug application in the US 1

Treatment Algorithm

1. Start with metoclopramide 5-10 mg PO QID before meals and at bedtime
2. If oral therapy ineffective for severe symptoms, switch to IV/IM administration
3. If symptoms persist, add a 5-HT3 antagonist (e.g., ondansetron)
4. Consider adding an anticholinergic agent (e.g., scopolamine) or antihistamine (e.g., meclizine) if needed 1
5. For patients who fail all standard therapies, consider gastric electrical stimulation or other interventional approaches 1

Remember that metoclopramide is the only FDA-approved medication specifically for gastroparesis, with all other agents considered off-label use 1.