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
[{'content': 'DOC for smoking cessation? \nSelect and explain. \nA. Acamprosate, B. Varenicline, C. Thalidomide, D. Tryptophan', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. Varenicline (If Bupropion is not an option)Anti-smoking drugs:Bupropion (along with Varenicline & Nicotine replacement therapy) is a USFDA approved first-line agent for pharmacotherapy in smoking cessation.Varenicline:Effective agent for smoking cessation.Synthetic drug with paial agonist action at a4ss2 nicotinic receptors.Has antagonist propeies persisting due to long half-life & high receptor affinity.Hence, prevents stimulant effect of nicotine at presynaptic a4ss2 receptors a results in dopamine release.', 'role': 'assistant'}]