This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET 2019, Subject name: Pharmacology
[{'content': 'Which of the following drug is used for smoking cessation? \nSelect and explain. \nA. Varenicline, B. Acamprostate, C. Nalmefene, D. Gabapentim', 'role': 'user'}, {'content': "Answer: A \nExplanation: DOC for smoking cessation : Varenicline Nicotine patch and gum are also used. Bupropion is also used in smoking cessation. Varenicline: is paial agonist at neuronal nicotinic acetylcholine receptor in CNS. Patient taking varenicline should be monitored for suicidal thoughts, vivid nightmares and mood changes. Acamprosate : agent used in alcohol dependent treatment programs with an as yet poorly understood mechanism of action. Gabapentin: analog of GABA: Does not act at GABA receptor. It's precise mechanism is not known. It is approved as adjunct therapy for focal seizure and treatment of post herpetic neuralgic. Nalmefene :- is opioid antagonist use for opioid poisoning", 'role': 'assistant'}]