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
Drug used for smoking cessation 
Select and explain. 
A. Varenicline, B. Nalmefene, C. Gabapentin, D. Acamprosate
A: Varenicline
Answer: A: Varenicline 
Explanation: Varenicline * Varenicline - paial agonist at alpha 3 beta 4, alpha 4 beta 2 & alpha 6 beta 2 subtypes of nAChRs and agonist at alpha 7 nicotinic Acetyl Choline Receptors. Block rewarding propeies of nicotine, alcohol and drugs of abuse. Ref:- Goodman & Gilman Pharmacological Basis of Therapeutics 13th Ed; Pg num:- 430