This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Pharmacology
[{'content': 'Which of the following drugs is LEAST effective luminal amoebicide? \nSelect and explain. \nA. Metronidazole, B. Diloxanide furoate, C. Iodoquinol, D. Paromomycin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (Ref: KDT 6/e p798, 799) Metronidazole is least effective luminal amoebicide because it is almost completely absorbed in small intestine and little drug is available to act in the colon.', 'role': 'assistant'}]