What are the criteria for taking Fosaprepitant (Aprepitant)?

Criteria for Taking Fosaprepitant (Aprepitant)

Fosaprepitant is FDA-approved for the prevention of nausea and vomiting associated with highly emetogenic chemotherapy (HEC) and moderately emetogenic chemotherapy (MEC), and should be administered as part of a three-drug regimen that includes a 5-HT3 receptor antagonist and dexamethasone. 1

Primary Indications

• Fosaprepitant is indicated for patients receiving:
  • Highly emetogenic chemotherapy (HEC) including cisplatin-based regimens 2
  • Combined anthracycline and cyclophosphamide (AC) regimens, which are classified as highly emetogenic 2
  • Moderately emetogenic chemotherapy (MEC) regimens 2

Dosing Regimens

Adult Patients

• For HEC:

  • Fosaprepitant 150 mg IV on day 1 only (30 minutes before chemotherapy) 2, 1
  • Dexamethasone 12 mg orally on day 1, then 8 mg orally on days 2-4 1
  • 5-HT3 antagonist on day 1 only (per specific medication guidelines) 2, 1

• For MEC:

  • Fosaprepitant 150 mg IV on day 1 only (30 minutes before chemotherapy) 1
  • Dexamethasone 12 mg orally on day 1 1
  • 5-HT3 antagonist on day 1 only (per specific medication guidelines) 2, 1

Pediatric Patients

• Fosaprepitant is approved for pediatric patients 6 months and older 1
• Dosing is weight-based:
  • 12-17 years: 150 mg IV over 30 minutes 1
  • 2 to <12 years: 4 mg/kg (maximum 150 mg) IV over 60 minutes 1
  • 6 months to <2 years: 5 mg/kg (maximum 150 mg) IV over 60 minutes 1

Administration Guidelines

• Administer fosaprepitant intravenously over 20-30 minutes in adults 1
• Complete the infusion approximately 30 minutes prior to chemotherapy 1
• For pediatric patients, administer over 30 minutes (12-17 years) or 60 minutes (6 months to <12 years) 1
• Fosaprepitant 150 mg IV on day 1 eliminates the need for oral aprepitant on days 2-3 2

Important Contraindications

• Fosaprepitant should not be administered to patients taking:
  • Pimozide 2
  • Terfenadine 2
  • Astemizole 2
  • Cisapride 2

Drug Interactions

• Fosaprepitant/aprepitant is a substrate, moderate inducer, and moderate inhibitor of CYP3A4 2
• Fosaprepitant/aprepitant also induces CYP2C9 2
• Use with caution in patients receiving:
  • Chemotherapeutic agents metabolized by CYP3A4 (docetaxel, paclitaxel, etoposide, irinotecan, ifosfamide, imatinib, vinorelbine, vinblastine, vincristine) 2
  • Warfarin (may reduce INR values, particularly in patients on therapeutic regimens) 2
  • Oral contraceptives (may decrease effectiveness) 2
  • Dexamethasone and methylprednisolone (requires dose adjustment - 50% reduction of dexamethasone is recommended) 2, 1

Clinical Efficacy Considerations

• Fosaprepitant has been shown to be noninferior to the standard 3-day oral aprepitant regimen 2, 3
• Particularly effective for preventing delayed emesis (24-120 hours after chemotherapy) 2, 4
• Single-dose fosaprepitant blocks >90% of NK-1 receptors in the CNS for at least 48 hours 4
• Complete response rates (no vomiting, no rescue medication) are significantly higher with fosaprepitant compared to placebo in both adults and children 5, 6

Special Populations

• Pediatric patients: Efficacy demonstrated in children aged 6 months to 17 years 1, 6
• No studies show efficacy or safety of chronic dosing with fosaprepitant 2

Common Adverse Events

• Infusion-site reactions (more frequent than with oral aprepitant) 4
• Other adverse events are generally consistent with those observed in patients receiving emetogenic chemotherapy 3

Important Limitations

• Fosaprepitant has not been studied for the treatment of established nausea and vomiting 1
• Drug interactions are more significant with orally administered forms than with intravenous forms due to first-pass metabolism 2

Fosaprepitant provides a convenient single-dose alternative to the 3-day oral aprepitant regimen while maintaining equivalent efficacy in preventing chemotherapy-induced nausea and vomiting 3, 4.