Effects of Naltrexone on Nicotine Reinforcement

"All participants took naltrexone during one of the two 4-day study medication periods. Both 4-day study medication periods were randomized and counterbalanced between naltrexone and placebo; all study medication periods were separated by a 5-7 day washout period.~Dosing of the naltrexone was the same for all participants: Day 1: 12.5mg, Day 2: 25mg, Days 3 and 4: 50mg."

"All participants took a placebo (sugar pill) during one of the two 4-day study medication periods. Both 4-day study medication periods were randomized and counterbalanced between naltrexone and placebo.~Placebo capsules matched the naltrexone in color, weight and inactive ingredients. The only difference the lack of active naltrexone in each capsule."