Varenicline tartrate (VAR) (Pfizer Int., Groton, CT), in doses of 0.5, 1.0, and 2.0 mg/kg BW, was incorporated into flavored, star-shaped pieces of gelatin that were voluntarily consumed by the rats, as previously described (Froehlich et al., 2013a, b, 2016, 2017). The volume of each gelatin star (approximately 1.8 g) was determined by the body weight of each rat on a daily basis. The gelatin star was inserted through a hole in the front of the cage. All of the rats consumed the gelatin star within 1 minute. Cages were checked to confirm that no small pieces of gelatin were dropped. If pieces were dropped, which was rare, they were refed to the rat. Gelatin stars were fed once each day at 1 hour prior to onset of the daily 2-hour alcohol access period because the half-life of VAR in the rat is short (4.0 ± 0.9 hours) (Obach et al., 2006). This oral drug delivery approach can be used for any water soluble drug that is orally active. It is well suited for chronic drug delivery because it eliminates stress and conditioned aversion to handling and eliminates the potential for harming the animal.
