This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
True regarding ondansetron are all of the following except: March 2010 
Select and explain. 
A. Antiemetic of choice for chemotherapy induced vomiting, B. 5-HT3 receptor antagonist, C. Significant drug interactions, D. May have 5-HT4 antagonism
C: Significant drug interactions
Answer: C: Significant drug interactions 
Explanation: Ans. C: Significant Drug Interactions Ondansetron is the prototype of new class of antiemetic drugs developed to control chemotherapy/radiotherapy induced vomiting, and later found to be highly effective in postoperative nausea and vomiting as well. It blocks the action of 5-HT through 5-HT3 receptors on vagal afferents in the GIT as well as in NTS and CTZ. A minor 5-HT4 antagonistic action has also been shown. It is hydroxylated by CYP 1A2, 2D6 and 3A, but no clinically significant drug interactions have been noted.