Varenicline dose dependently enhances responding for nonpharmacological reinforcers and attenuates the reinforcement-enhancing effects of nicotine.
Levin ME, Weaver MT, Palmatier MI, Caggiula AR, Sved AF, Donny EC. Varenicline dose dependently enhances responding for nonpharmacological reinforcers and attenuates the reinforcement-enhancing effects of nicotine. Nicotine Tob Res. 2012 Mar; 14(3):299-305.