Which of the following is the most potent 5HT3 antagonist -

Ans. is 'd' i.e., Palonasetrono Among 5HT3 antagonists, Palonosetron has maximum affinity for 5HT3 receptor.o 5-HT3 receptor antagonists (ondansetron, granisetron and tropisetron) are DOCs for chemotherapy induced vomiting.o When used alone, these drugs have no efficacy for the prevention of delayed nausea and vomiting (i.e., occurring >24 hours after chemotherapy ). These drugs are most effective when given as a single dose by intravenous injection 30 minutes prior to administration of chemotherapy.Newer Drug:o Alosetron is a 5HT3 antagonist that has been approved for the treatment of patients with severe IBS with diarrhea.