What is the regimen for prophylactic dosing when starting chemotherapy?

Prophylactic Regimens for Chemotherapy-Induced Nausea and Vomiting

The optimal prophylactic antiemetic regimen for chemotherapy should be tailored based on the emetogenic potential of the chemotherapy regimen, with a three-drug combination of a 5-HT3 antagonist, dexamethasone, and aprepitant recommended for highly emetogenic chemotherapy. 1

Antiemetic Regimens Based on Emetogenic Potential

Highly Emetogenic Chemotherapy

• Day 1:
  • 5-HT3 antagonist (preferably palonosetron 0.25 mg IV)
  • Dexamethasone (12 mg IV)
  • Aprepitant (125 mg PO) or fosaprepitant (115 mg IV)
• Days 2-3:
  • Dexamethasone (8 mg PO/IV daily)
  • Aprepitant (80 mg PO daily) if used on day 1

Moderately Emetogenic Chemotherapy

• Day 1:
  • 5-HT3 antagonist (preferably palonosetron)
  • Dexamethasone (8 mg IV/PO)
  • ± Aprepitant (125 mg PO) for selected agents (e.g., carboplatin, cisplatin, doxorubicin)
• Days 2-3: One of the following:
  • Aprepitant (80 mg PO daily) if used on day 1
  • Dexamethasone (8 mg PO/IV daily)
  • 5-HT3 antagonist (except palonosetron)

Low Emetogenic Chemotherapy

• Single agent: Dexamethasone (8 mg IV/PO) or prochlorperazine or metoclopramide
• ± Lorazepam (0.5-2 mg every 4-6 hours)
• ± H2 blocker or proton pump inhibitor

Specific Dosing Guidelines

Ondansetron (5-HT3 antagonist)

• For highly emetogenic chemotherapy: 24 mg PO administered 30 minutes before chemotherapy 2
• For moderately emetogenic chemotherapy: 8 mg PO administered 30 minutes before chemotherapy, with a subsequent 8 mg dose 8 hours after the first dose, then 8 mg twice daily for 1-2 days 2

Palonosetron

• 0.25 mg IV on day 1 only (not repeated on subsequent days) 1
• Preferred 5-HT3 antagonist for moderately emetogenic chemotherapy due to superior efficacy in preventing both acute and delayed nausea/vomiting 1

Important Considerations

1. Timing is critical:

   • Antiemetics should be administered before chemotherapy begins
   • 5-HT3 antagonists: 30 minutes before chemotherapy
   • Dexamethasone: immediately before chemotherapy
   • Aprepitant: 1 hour before chemotherapy

2. Prevention is key:

   • Prophylactic treatment is much more effective than treating established nausea/vomiting
   • For delayed emesis, continue prophylaxis for 2-4 days after completion of chemotherapy cycle 1

3. Common pitfalls to avoid:

   • Administering growth factors on the same day as chemotherapy (should be given 24-72 hours after completion) 1
   • Using single-agent therapy for highly emetogenic regimens
   • Underdosing antiemetics for highly emetogenic regimens
   • Neglecting to provide prophylaxis for delayed nausea/vomiting

4. Special considerations:

   • For multi-day chemotherapy regimens, antiemetics should be given each day before chemotherapy
   • For oral chemotherapeutic agents with high/moderate emetic risk, prophylaxis with oral 5-HT3 antagonists is recommended 1

Breakthrough Nausea and Vomiting

If breakthrough nausea/vomiting occurs despite prophylaxis:

• Add an agent from a different drug class
• Consider around-the-clock dosing rather than PRN
• Use IV or rectal route if oral intake is compromised
• Options include metoclopramide, haloperidol, corticosteroids, or lorazepam
• Ensure adequate hydration and electrolyte replacement 1

By implementing these evidence-based prophylactic antiemetic regimens, you can significantly reduce the incidence and severity of chemotherapy-induced nausea and vomiting, improving both treatment adherence and quality of life for patients undergoing chemotherapy.