Specific 5HT3 antagonist used for nausea and vomiting secondary to chemo therapy*1 pointMethylgersideOndansetronMetoclopromideBaclofen

The specific 5HT3 antagonist used for nausea and vomiting secondary to chemotherapy is Ondansetron.

Explanation

1. 5HT3 Antagonists: These drugs work by blocking serotonin receptors in the gastrointestinal tract and the central nervous system, which can help reduce the feeling of nausea and the urge to vomit, particularly in patients undergoing chemotherapy.
2. Ondansetron: This is the most commonly used medication in this class for managing nausea and vomiting specifically related to chemotherapy treatments. It is effective and well-tolerated.
3. Other Options:
   • Methylgerside is not a recognized medication for this indication.
   • Metoclopramide works differently; it is primarily an antiemetic and prokinetic agent but not exclusively a 5HT3 antagonist.
   • Baclofen is a muscle relaxant and not used for nausea or vomiting.

Therefore, the correct answer is Ondansetron.