Aprepitant is a neurokinin-1 (NK1) receptor antagonist, primarily used to prevent acute and delayed nausea and vomiting caused by chemotherapy (especially highly emetogenic and moderately emetogenic chemotherapy). Despite its significant efficacy, potential side effects and special precautions must be closely monitored during medication use.

What Are the Side Effects of Aprepitant?

Common Adverse Reactions in Adult Patients

Systemic reactions: Fatigue (13%), weakness (7%), dehydration (3%).

Digestive system: Diarrhea (9%), dyspepsia (7%), abdominal pain (6%), nausea and vomiting (though it is a preventive medication, these symptoms may still occur).

Skin and subcutaneous tissue: Rash, pruritus, hyperhidrosis.

Abnormal laboratory findings: Decreased white blood cell count (4%), elevated alanine aminotransferase (3%).

Common Adverse Reactions in Pediatric Patients

Hematological system: Neutropenia (13%), decreased hemoglobin (5%).

Nervous system: Headache (9%), dizziness (5%).

Others: Cough (5%), decreased appetite (5%), hiccups (4%).

Severe Side Effects of Aprepitant Requiring Vigilance

Allergic Reactions

Manifestations: Include urticaria, angioedema, skin exfoliation (e.g., Stevens-Johnson syndrome), and even anaphylactic shock.

If symptoms such as difficulty breathing or severe rash occur, discontinue the medication immediately and seek medical attention.

QT Interval Prolongation and Arrhythmia

Risk scenario: Concurrent use with other QT-prolonging drugs (e.g., pimozide) may induce torsades de pointes.

Concurrent use with pimozide is contraindicated.

Failure of Hormonal Contraceptives

Mechanism: Aprepitant can reduce the plasma concentration of estrogen-containing contraceptives. Non-hormonal contraceptive measures (e.g., condoms) must be used during medication and for 1 month after discontinuing the drug.

Decreased Efficacy of Warfarin

Monitoring requirement: When used in combination with warfarin, the International Normalized Ratio (INR) should be closely monitored 7–10 days after starting Aprepitant to prevent insufficient anticoagulation.

Precautions for Aprepitant Administration

Medication in Special Populations

Hepatic impairment: No dosage adjustment is needed for mild to moderate hepatic impairment; use with caution in patients with severe hepatic impairment.

Renal impairment: No dosage adjustment is required, including for patients undergoing hemodialysis.

Pregnant and lactating women: Use only when necessary; for lactating women, the benefits and risks must be weighed.

Management of Drug Interactions

Contraindicated concurrent drugs: Pimozide (due to the risk of QT interval prolongation).

Drugs requiring dosage adjustment:

Dexamethasone: The dose should be reduced by 50% (because Aprepitant inhibits its metabolism).

Methylprednisolone: Reduce the intravenous dose by 25% and the oral dose by 50%.

Patient Education

Administration timing: Take the medication strictly according to the chemotherapy schedule. If chemotherapy is only administered on Day 1, the medication should still be taken in the morning on Days 2–3.

Dosage form selection: Capsules should be swallowed whole; for patients unable to swallow, oral suspension (to be prepared by medical staff) can be used.

Storage conditions: After preparation, the suspension should be refrigerated (2–8°C) and used within 72 hours. It should not be left at room temperature for more than 3 hours.