Mechanism of Action of Ondansetron
Ondansetron is a potent antiemetic that acts as:
- D2 antagonist
- H1 antagonist
- Muscarinic antagonist
- 5HT3 antagonist — Correct Answer
Explanation:
Correct Answer: 5HT3 antagonist
Ondansetron is a 5HT3 antagonist and is a potent antiemetic. It is very effective in patients receiving cancer chemotherapy. It can also be used for CTZ-mediated nausea.
Classification of Centrally Acting Antiemetics
- Phenothiazines (broad-spectrum): Chlorpromazine, prochlorperazine — block CTZ at low doses, emetic center at high doses.
- Metoclopramide: D2 antagonist + weak 5HT3 antagonist; also a prokinetic.
- Ondansetron: 5HT3 antagonist — especially useful in chemotherapy-induced vomiting.
- Hyoscine (scopolamine): Muscarinic antagonist (M2) — for CTZ-mediated vomiting.
- Xylazine: Used as an emetic in cats (alpha-2 agonist).
📚 About this Topic — Veterinary Pharmacology and Toxicology
This multiple choice question is from Veterinary Pharmacology and Toxicology, Veterinary Science. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Veterinary Pharmacology and Toxicology to strengthen your preparation.
