This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Ulcer, Subject name: Pharmacology
[{'content': 'Drug not used in the treatment of H.pylori is? \nSelect and explain. \nA. Cisapride, B. Clarithromycin, C. Metronidazole, D. Omeprazole', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ANSWER: (A) CisaprideREF: Harrison 17th ed table 144-2Recommended Treatment Regimens for Helicobacter pylori:First-Line Treatment:Regimen 1: OCA (7-14 days)Omeprazoleb (20 mg bid)Clarithromycin (500 mg bidAmoxicillin (1 g bid)Regimen 2: OCM (7-14 days)Omeprazoleb (20 mg bid)Clarithromycin (500 mg bid)Metronidazole (500 mg bid)Second-Line Treatment:Regimen 3: OBTM (14 days)Omeprazoleb (20 mg bid)Bismuth subsalicylate (2 tabs qid)Tetracycline HC1 (500 mg qid)Metronidazole (500 mg tid)', 'role': 'assistant'}]