What is the recommended dosing regimen for Emend (aprepitant) in preventing chemotherapy-induced nausea and vomiting?

Recommended Dosing Regimen for Emend (Aprepitant) in CINV Prevention

The recommended oral dosing regimen for Emend (aprepitant) for prevention of chemotherapy-induced nausea and vomiting (CINV) is 125 mg on day 1 (one hour before chemotherapy) followed by 80 mg on days 2 and 3 after chemotherapy. 1

Standard Dosing Protocol

Highly Emetogenic Chemotherapy (HEC)

• Day 1:

  • Aprepitant 125 mg PO (1 hour before chemotherapy)
  • Dexamethasone 12 mg PO (30 minutes before chemotherapy)
  • 5-HT3 antagonist (e.g., ondansetron 8 mg IV or 16-24 mg PO)

• Day 2:

  • Aprepitant 80 mg PO in the morning
  • Dexamethasone 8 mg PO

• Day 3:

  • Aprepitant 80 mg PO in the morning
  • Dexamethasone 8 mg PO

• Day 4:

  • Dexamethasone 8 mg PO 2, 1

Moderately Emetogenic Chemotherapy (MEC)

• Day 1:

  • Aprepitant 125 mg PO (1 hour before chemotherapy)
  • Dexamethasone 12 mg PO (30 minutes before chemotherapy)
  • 5-HT3 antagonist (e.g., ondansetron 8 mg IV or 16-24 mg PO)

• Day 2:

  • Aprepitant 80 mg PO in the morning

• Day 3:

  • Aprepitant 80 mg PO in the morning 2, 1

Alternative IV Formulation Option

For patients who cannot tolerate oral medication, fosaprepitant (IV formulation of aprepitant) can be substituted:

• Single-dose regimen: Fosaprepitant 150 mg IV on day 1 only (30 minutes before chemotherapy)
  • When using this higher dose (150 mg IV), oral aprepitant is not needed on days 2-3
  • Note: Dexamethasone dosing changes to 8 mg twice daily on days 3-4 when using this regimen 2

Important Clinical Considerations

1. Drug Interactions:

   • Aprepitant affects CYP3A4 and CYP2C9 enzymes
   • Reduce dexamethasone dose by 50% when used with aprepitant due to drug interactions 2, 3
   • Contraindicated with pimozide, terfenadine, astemizole, and cisapride 2
   • Use caution with chemotherapeutic agents metabolized by CYP3A4 (docetaxel, paclitaxel, etoposide, irinotecan, etc.)

2. Efficacy Data:

   • Significantly improves complete response rates for both acute and delayed CINV
   • Particularly beneficial for patients receiving anthracycline plus cyclophosphamide regimens 4
   • Effective across a broad range of moderately emetogenic chemotherapy regimens 5

3. Administration Details:

   • Can be taken with or without food
   • Capsules should be swallowed whole 1
   • Administer 1 hour before chemotherapy on day 1 1

4. Special Populations:

   • Approved for patients 12 years and older 1
   • No dose adjustment needed for elderly patients or those with renal insufficiency

5. Limitations:

   • Not indicated for treatment of established nausea and vomiting
   • Chronic continuous administration is not recommended 1

The evidence strongly supports the triple-therapy regimen (aprepitant + 5-HT3 antagonist + dexamethasone) for prevention of CINV, with complete response rates significantly higher compared to standard dual therapy, particularly for delayed emesis control 2, 3.

Remember that while the standard oral regimen is 3 days, the single-dose IV fosaprepitant 150 mg option has been shown to be non-inferior to the 3-day oral regimen and may improve compliance in certain clinical scenarios 2.