Fosaprepitant — Drug Monograph

Brand names: Emend IV

Drug class: Supportive Care Agent

Mechanism of Action

Prodrug of aprepitant. Fosaprepitant is rapidly converted to aprepitant after IV administration (within ~30 minutes). Aprepitant then exerts selective NK1 receptor antagonism, blocking substance P–mediated delayed CINV. A single IV dose of 150 mg fosaprepitant provides equivalent aprepitant exposure to the 3-day oral aprepitant regimen (125 mg Day 1, 80 mg Days 2–3), enabling once-per-cycle single-dose IV therapy.

FDA Indications

• Prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of highly emetogenic chemotherapy, including high-dose cisplatin — in combination with other antiemetics
• Prevention of nausea and vomiting associated with moderately emetogenic chemotherapy — in combination with other antiemetics

Common Side Effects

• Infusion site reactions — injection site pain, erythema, phlebitis (more common than oral aprepitant)
• Fatigue
• Hiccups
• Constipation
• Diarrhea
• Nausea

Clinical Pearl

Fosaprepitant 150 mg IV (single Day 1 dose) provides equivalent systemic aprepitant exposure to the full 3-day oral schedule and simplifies administration significantly — the patient does not need to take oral pills on Days 2 and 3. Infusion-site reactions are a practical concern; central venous access or a large-bore peripheral line in the antecubital fossa reduces risk. If the patient has an existing central line for chemotherapy, piggyback fosaprepitant into the line after flushing with NS.

Related Therapies & Mechanisms

• Aprepitant (Emend) — Supportive Care Agent
• Avatrombopag (Doptelet) — Supportive Care Agent
• Darbepoetin Alfa (Aranesp) — Supportive Care Agent
• Defibrotide (Defitelio) — Supportive Care Agent