Possibly through their actions upon glia, peroxisome proliferator-activated receptor agonists (PPAR) have been shown to alter the abuse potential of addictive drugs in several preclinical models. The current study extends this research into the human laboratory as the first clinical study into the effects of the PPAR gamma agonist, pioglitazone, on the abuse potential of nicotine. Heavy smokers were recruited for this 3-week study. Upon admission, participants were randomized to either active (45 mg, n = 14) or placebo (0 mg, n = 13) PIO maintenance conditions for the duration of the study. After 5–7 days of stabilization on a 7 mg nicotine patch, participants began laboratory testing. On the 1st–4th test days, participants could self-administer cigarettes or receive money by making verbal choices for either option. On the 5th day, participants were administered 10 puffs of their usual brand of cigarette in the morning and later chose between smoking and money by making finger presses on a computer mouse in a progressive ratio self-administration task. Later on the 5th day participants also underwent a smoking cue exposure session. The 8th–11th test days were identical to the 1st–4th test days with the exception that during one of the test weeks de-nicotinized cigarettes were available, and during the other nicotinized cigarettes were available. Nicotinized cigarettes were always administered on the 5th and 12th days. On some measures PIO increased indicators of abuse potential, though this effect was typically not statistically significant. However, PIO did significantly reduce measures of craving.

Preclinical data indicate that selective kappa opioid receptor antagonists reduce nicotine self‐administration and withdrawal symptoms. The aim of the current study was to determine whether treatment with CERC‐501, an orally available, potent, and selective kappa opioid receptor antagonist, could alleviate nicotine withdrawal and craving and mitigate mood alterations associated with nicotine withdrawal in humans. Healthy, adult cigarette smokers were enrolled into this randomized, multisite, double‐blind, placebo‐controlled, crossover study. Participants completed two 8‐day treatment phases during which they received either CERC‐501 (15 mg, p.o., once daily) or placebo. On the seventh day of each dosing phase, participants were admitted as inpatients for an 18‐hour cigarette abstinence period followed by experimental testing. The primary outcome measures were (a) performance on the McKee Smoking Lapse test (ie, latency to smoke in exchange for money) and (b) number of cigarettes self‐administered during a 60‐minute ad lib smoking period. Other outcomes included measures of craving, mood, anxiety, nicotine withdrawal, and subjective effects of cigarette smoking. A total of 71 participants who smoked an average of approximately 23 cigarettes per day were enrolled, and 56 subjects completed the study. CERC‐501 was well tolerated, but it did not significantly alter the latency to start smoking (CERC‐501: 16.5 min vs placebo: 17.7 min) or the number of cigarettes smoked (CERC‐501: 3.3 cigarettes vs placebo: 3.1 cigarettes). Compared with placebo, CERC‐501 also did not affect cigarette craving, mood, anxiety, nicotine withdrawal, or subjective effects of smoking. These findings do not support a role for CERC‐501 in the treatment of nicotine use disorder.

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