Generic Name

Fosaprepitant Dimeglumine

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Classification

FDA Approved Indications

• Prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of chemotherapy, including high-dose chemotherapy regimens.

Mechanism of Action

Fosaprepitant is a prodrug of aprepitant, which selectively antagonizes substance P/neurokinin 1 (NK1) receptors in the central nervous system, blocking the emetic signaling pathway.

Dosage and Administration

Adult: 150 mg IV administered as a single dose approximately 30 minutes prior to chemotherapy.

Pediatric: Not approved for pediatric use; safety and efficacy not established.

Geriatric: Adjust dosing based on renal and hepatic function; no specific dose adjustment required solely based on age.

Renal Impairment: No adjustment recommended, but cautious use advised in severe impairment.

Hepatic Impairment: Adjust dose in severe hepatic impairment; consult prescribing information.

Pharmacokinetics

Absorption: Rapid conversion from prodrug to active form, with rapid distribution.

Distribution: Widely distributed in tissues, crosses the blood-brain barrier.

Metabolism: Metabolized primarily in the liver via CYP3A4.

Excretion: Excreted mainly in feces; minimal renal excretion.

Half Life: Approximately 9-13 hours for the active metabolite.

Contraindications

• Hypersensitivity to fosaprepitant or any component of the formulation.

Precautions

• Use with caution in patients with hepatic impairment; monitor for drug interactions, especially with CYP3A4 substrates.

Adverse Reactions - Common

• Hiccups (Frequent)
• Fatigue (Less frequent)

Adverse Reactions - Serious

• Hypersensitivity reactions (rash, anaphylaxis) (Rare)
• Elevated liver enzymes (Uncommon)

Drug-Drug Interactions

• CYP3A4 substrates (may increase levels)
• Corticosteroids (may require dose adjustment)
• Warfarin (potential interaction)

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Report any allergic symptoms immediately.
• Take antiemetics as prescribed.
• Maintain hydration.

Special Considerations

Black Box Warnings:

• Use with caution in patients receiving therapies with significant CYP3A4 interactions; potential for decreased effectiveness of oral contraceptives.

Genetic Factors: Genetic variations in metabolizing enzymes may affect drug levels.

Lab Test Interference: May elevate liver function tests transiently.

Overdose Management

Signs/Symptoms: Unknown, but may include hypersensitivity or infusion reactions.

Treatment: Supportive care; symptomatic management; no specific antidote.

Storage and Handling

Storage: Store at room temperature, away from light and moisture.

Stability: Stable under recommended storage conditions.