A 55-year-old man on cisplatin-based chemotherapy receives ondansetron plus dexamethasone before each cycle but continues to vomit predominantly between 24 and 120 hours after infusion. The most appropriate addition to his antiemetic regimen is:

• A Metoclopramide at prokinetic dose
• B Hyoscine (scopolamine)
• C Lorazepam
• D Aprepitant ✓

Explanation

The delayed phase of chemotherapy-induced nausea and vomiting (24 to 120 hours, classically after cisplatin) is mediated largely by substance P acting at neurokinin-1 receptors in the vomiting centre. Aprepitant, an NK-1 receptor antagonist, added to ondansetron and dexamethasone specifically covers this phase. Scopolamine targets vestibular motion sickness pathways, lorazepam provides anticipatory anxiety relief, and metoclopramide alone is inferior for delayed CINV.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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