A patient undergoing cancer chemotherapy is vomiting frequently. The drug of choice in this case is?

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

Ondansetron is a selective 5-HT3 receptor antagonist, which is the first-line and prototypical drug for managing Chemotherapy-Induced Nausea and Vomiting (CINV).
Its mechanism involves blocking serotonin (5-HT) at the 5-HT3 receptors, both peripherally on vagal nerve terminals in the GI tract and centrally in the chemoreceptor trigger zone (CTZ).
Chemotherapeutic agents cause damage to the GI mucosa, leading to a release of serotonin, which initiates the vomiting reflex. Ondansetron directly interrupts this pathway.

Option A: Ergotamine is a vasoconstrictor used for treating acute migraine headaches, not for nausea and vomiting.
Option C: Cimetidine is an H2-receptor antagonist that reduces stomach acid. While it treats gastrointestinal issues like ulcers and GERD, it is not an antiemetic for CINV.
Option D: Bromocriptine is a dopamine agonist used to treat Parkinson's disease and conditions involving high prolactin levels. Nausea and vomiting are common side effects of this drug.

Clinical Relevance

Nursing practice connection: Use the key finding related to Pharmacological management of Chemotherapy-Induced Nausea and Vomiting (CINV) to guide bedside assessment, documentation, and the next nursing action.
Controlling CINV is critical in oncology nursing to ensure patient comfort, maintain nutritional status, and improve adherence to life-saving chemotherapy regimens.
Nurses are responsible for administering antiemetics prophylactically, assessing their effectiveness, managing side effects, and educating the patient and family on CINV management at home.
What if the patient experiences vomiting more than 24 hours after chemotherapy (delayed CINV)? The answer might change. For delayed CINV, other agents like NK1 receptor antagonists (e.g., aprepitant) are often added to the 5-HT3 antagonist regimen for better control.

How to Approach the Question

First, identify the core clinical problem presented in the question: frequent vomiting in a patient receiving cancer chemotherapy.
Recognize this specific condition as Chemotherapy-Induced Nausea and Vomiting (CINV), a common and significant side effect.
Recall the primary drug classes used to manage CINV. The 5-HT3 receptor antagonists are a cornerstone of treatment.
Evaluate the given options. Identify Ondansetron as a member of the 5-HT3 antagonist class.
Consider the mechanisms of the other drugs: Ergotamine (migraine), Cimetidine (acid reduction), and Bromocriptine (dopamine agonist). Confirm they are not indicated for CINV.
Conclude that Ondansetron is the most appropriate and specific choice for this clinical scenario.

Concept Tested & Keywords

Concept Tested: Pharmacological management of Chemotherapy-Induced Nausea and Vomiting (CINV)
Stem keywords: cancer chemotherapy, vomiting frequently
Lead-in keywords: drug of choice
Negative lead-in flag: false

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E6 Pharmacology Nursing Lilley 11e Part 3 p. 188-190

E6 Pharmacology KD Tripathi Essentials 9e Part 2 p. 342-344

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Attempt every question from this paper in a timed mock, then review the full solution for each one.