This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti Histaminics, Subject name: Pharmacology
H2 blocker used as anti-ulcer drug: 
Select and explain. 
A. Pirenzepine, B. Famotidine, C. Rabeprazole, D. Sucralfate
B: Famotidine
Answer: B: Famotidine 
Explanation: Ans: b (Famotidine) Ref: KDT, 6th ed,p. 629DRUGS USED IN PEPTIC ULCER1) H2 antagonists - Ranitidine, cimetidine. famotidine roxatidine and nizatidine.Nizatidine has little first-pass metabolism and a bioavailability of almost 100%. Famotidine is the most potent among them.2) Proton pump inhibitors (PPIs) - Omeprazole, lansoprazole, rabeprazole, pantoprazole, and esomeprazole.They are the most effective drugs in GERD.3) Mucosal protective agents - Sucralfate, colloidal bismuth compounds4) Prostaglandin analogs - Misoprostol5) Antacids6) Anticholinergics - Pirenzipine, propantheline7) Anti-H.pylori drugs - Amoxicillin, clarithromycin, metronidazole, tinidazole, tetracycline.