Which receptor subtype is varenicline primarily targeted at?

• A. Alpha4beta2 nicotinic receptor
• B. Mu opioid receptor
• C. D2 receptor
• D. GABA-B receptor

Answer: (A)

Varenicline’s primary action is as a selective partial agonist at the alpha4beta2 nicotinic acetylcholine receptor in the brain. By partially activating this receptor, it eases withdrawal and cravings, while also blocking nicotine from producing its full rewarding dopamine surge because nicotine cannot fully activate the receptor in the presence of varenicline. This dual effect makes it effective for smoking cessation. The other receptors listed aren’t the main targets: mu opioid receptors relate to opioid reward and pain but aren’t how varenicline works; D2 receptors are involved in dopamine signaling but varenicline doesn’t directly target them; GABA-B receptors are inhibitory neurotransmitter receptors not central to varenicline’s mechanism.