A breast cancer patient receiving highly emetogenic cisplatin chemotherapy is given ondansetron plus dexamethasone for acute vomiting, and aprepitant is added specifically to control vomiting occurring more than 24 hours after chemotherapy. Aprepitant achieves this by:

• A Blocking 5-HT3 receptors in the chemoreceptor trigger zone
• B Inhibiting dopamine D2 receptors in the chemoreceptor trigger zone
• C Antagonising substance P at neurokinin-1 receptors in the vomiting centre and area postrema ✓
• D Enhancing gastric emptying through 5-HT4 agonism

Explanation

Substance P acting at neurokinin-1 receptors in the nucleus tractus solitarius and area postrema is a key mediator of both acute and especially delayed-phase emesis. Aprepitant is a selective NK1 receptor antagonist and, combined with a 5-HT3 blocker and dexamethasone, improves control of delayed CINV after cisplatin. It is a moderate CYP3A4 inhibitor, so it interacts with dexamethasone and warfarin. Dopamine and serotonin pathways are targeted by other drug classes.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.