Drug of choice for cisplatin induced emesis is :
**Core Concept**
Cisplatin-induced emesis is a type of acute chemotherapy-induced nausea and vomiting (CINV), which is a major side effect of platinum-based chemotherapy agents like cisplatin. This condition involves a complex interplay of neurotransmitters, hormones, and the central nervous system, leading to intense nausea and vomiting.
**Why the Correct Answer is Right**
Ondansetron, a serotonin 5-HT3 receptor antagonist, is the drug of choice for cisplatin-induced emesis. This is because the 5-HT3 receptors are located in the central nervous system and the vomiting center, and their activation is a key step in the pathophysiology of CINV. Ondansetron works by competitively inhibiting the 5-HT3 receptors, thus blocking the afferent signals to the vomiting center and preventing nausea and vomiting.
**Why Each Wrong Option is Incorrect**
**Option A:** Metoclopramide is a dopamine antagonist and a prokinetic agent, but it is not the first-line treatment for cisplatin-induced emesis due to its side effects and limited efficacy in CINV.
**Option B:** Aprepitant is a substance P/neurokinin 1 (NK1) receptor antagonist, which is used as an adjunct therapy to ondansetron for CINV, but it is not the primary treatment.
**Option C:** Dexamethasone is a corticosteroid that is often used in combination with ondansetron for CINV, but it is not the drug of choice for cisplatin-induced emesis.
**Clinical Pearl / High-Yield Fact**
For optimal management of CINV, the World Health Organization (WHO) recommends a three-drug combination of a 5-HT3 antagonist (like ondansetron), a corticosteroid (like dexamethasone), and an NK1 receptor antagonist (like aprepitant).
**Correct Answer:** C. Ondansetron