Effects of atomoxetine on subjective and neurocognitive symptoms of nicotine abstinence

Nicotine dependence has been linked to attention-deficit hyperactivity disorder (ADHD) symptoms in both clinical and general populations. This behavioural pharmacology study used a within-subject, double-blind, crossover design to test the effects of atomoxetine, a medication for ADHD, on nicotine abstinence symptoms. Fifty non treatment-seeking smokers (>/=15 cigarettes/day) completed a baseline session when they were smoking as usual and then two laboratory testing sessions after overnight abstinence and treatment with 7 days of either atomoxetine (1.2 mg/kg) or placebo. During each laboratory session, participants completed subjective measures of abstinence symptoms and performed neurocognitive tasks. In mixed effects models, atomoxetine, compared with placebo, was found to be associated with a reduction in abstinence-induced subjective withdrawal symptoms. Atomoxetine was also associated with significant reductions in self-reported smoking urges amongst smokers who scored high on a baseline measure of smoking for stimulation. However, atomoxetine had no effect on any of the cognitive tasks employed in the study. Thus, atomoxetine may reduce cravings to smoke among smokers who use nicotine to increase arousal.

Association of OPRM1 A118G variant with the relative reinforcing value of nicotine

RATIONALE

The endogenous opioid system has been implicated in substance abuse and response to pharmacotherapies for nicotine and alcohol addiction. We examined (1) the association of the functional OPRM1 A118G variant with the relative reinforcing value of nicotine and (2) the main and interacting effects of the mu-opioid receptor antagonist naltrexone on nicotine reinforcement.

METHODS

In a within-subject, double-blind human laboratory study, 30 smokers of each OPRM1 genotype (A/A vs. A/G or G/G) participated in two experimental sessions following 4 days of orally administered naltrexone 50 mg or placebo. Participants completed a validated assessment of the relative reinforcing value of nicotine. This cigarette choice paradigm assesses self-administration of 0.6 mg nicotine vs. 0.05 mg (denicotinized) cigarettes after a brief period of nicotine abstinence.

RESULTS

The relative reinforcing value of nicotine (number of nicotine cigarette puffs) was predicted by a significant OPRM1 by gender interaction. Among women, the low-activity G allele (A/G and G/G) was associated with a reduced reinforcing value of nicotine; among male smokers, there was no association with genotype. Smokers carrying a G allele were also significantly less likely to differentiate the nicotine vs. denicotinized cigarettes by subjective ratings of satisfaction and strength. No evidence for an effect of naltrexone on nicotine reinforcement was found in the overall sample or in the genotype or gender subgroups.

CONCLUSIONS

This study provides initial evidence for an association of the OPRM1 A118G variant with nicotine reinforcement in women.

The functional mu opioid receptor (OPRM1) Asn40Asp variant predicts short-term response to nicotine replacement therapy in a clinical trial

To determine whether the functional mu-opioid receptor (OPRM1) Asn40Asp variant predicts the comparative efficacy of different forms of NRT, we conducted a clinical trial of transdermal nicotine (TN) vs nicotine nasal spray (NS) in 320 smokers of European ancestry. Smokers carrying the OPRM1 Asp40 variant (n=82) were significantly more likely than those homozygous for the Asn40 variant (n=238) to be abstinent at the end of treatment, and reported less mood disturbance and weight gain. The genotype effect on treatment outcome was most pronounced among smokers receiving TN, particularly during the 21 mg dose phase. Smokers who carry the OPRM1 Asp40 variant are likely to have a favorable response to TN and may benefit from extended therapy with the 21 mg dose.

Predicting treatment response to naltrexone: the influence of craving and family history

Naltrexone has repeatedly been shown to reduce drinking in alcohol-dependent patients. Previous clinical research suggests that naltrexone may be more effective at reducing drinking among patients with high levels of alcohol craving at the beginning of treatment. In addition, laboratory studies suggest that naltrexone may be more efficacious among patients with a high familial loading of alcohol problems. We explored both of these possibilities in the context of the first 12-week phase of a double blind, placebo-controlled naltrexone trial. A total of 121 patients were randomized to receive 100 mg/day naltrexone and 62 patients were randomized to receive placebo. Both naltrexone and placebo were given in conjunction with a psychosocial intervention designed to be integrated with the use of pharmacotherapy. This intervention was administered by nurse practitioners. Overall, patients randomized to naltrexone reported drinking five or more drinks on fewer days than did placebo controls (p = .04). Interactions were observed between medication group assignment and both craving level prior to randomization (p = .02) and family loading of alcohol problems (p = .05). In both cases, the interaction was in the predicted direction. These data suggest that patients with high levels of alcohol craving or a strong family history of alcoholism are more likely to benefit from naltrexone treatment.

Effects of triazolam at three phases of the menstrual cycle

This study investigated the subjective and behavioral effects of a commonly used benzodiazepine, triazolam, in healthy women at three phases of the menstrual cycle: follicular, periovulatory, and luteal. Ovarian hormones or their metabolites have direct and indirect actions on neuronal receptors, which may affect responses to psychoactive drugs acting on the same central nervous system receptors. This study explored the effect of menstrual cycle phase on the mood-altering and performance effects of a single oral dose of the benzodiazepine triazolam. Twenty women received triazolam (0.25 mg orally) or placebo at the follicular, periovulatory, and luteal phases of their menstrual cycles in a within-subject design. Dependent measures included self-reported mood states, psychomotor performance, and plasma levels of triazolam, estradiol, progesterone, and allopregnanolone. After administration of triazolam, most subjects reported the expected increases in fatigue and decreases in arousal and psychomotor performance. Neither plasma levels nor mood and performance effects of triazolam differed across the three phases. This study illustrates a useful methodology for assessing responses to psychoactive drugs in normally cycling women and shows that the effects of this drug were highly stable across the cycle.

Open trials as a method of prioritizing medications for inclusion in controlled trials for cocaine dependence

This paper describes a rapid and systematic method of using open trials to identify medications that may be useful for the treatment of cocaine dependence. Results of these open trials can be used to prioritize medications for inclusion in subsequent double-blind, placebo-controlled trials. Preliminary results are presented from the evaluation of propranolol, nefazodone, and the combination of phentermine and fenfluramine (phen/fen). Each medication was evaluated in an open trial, and results were compared to results obtained from a group that received a multivitamin. Outcome measures included treatment retention, urine toxicology screens, self-reported cocaine use, and changes on the Addiction Severity Index (ASI). Treatment retention was significantly better in the propranolol group than in the multivitamin group. Concurrent alcohol abuse was associated with increased rates of attrition in the multivitamin group, and the phen/fen group, but not in the propranolol group. Neither the nefazodone nor the phen/fen groups showed any outcome advantages over the multivitamin group. We conclude that propranolol may enhance retention among cocaine-dependent patients, especially among those who also abuse alcohol. These results encourage a double-blind, placebo-controlled trial of propranolol.

Acute effects of triazolam in women: relationships with progesterone, estradiol and allopregnanolone

This study investigated hormone levels and mood in normal women to explore relationships between levels of circulating hormones and i) baseline mood states and ii) effects of triazolam on mood. Certain ovarian hormones or their metabolites have direct actions on neuronal receptors. These actions may result in changes in mood state, or changes in responses to psychoactive drugs which act on the same receptors. The present study explored relationships between estrogen, progesterone and a metabolite of progesterone, allopregnanolone, and the mood-altering and performance effects of an acute dose of triazolam. Triazolam is a short-acting benzodiazepine which acts via the GABAA receptor complex. Twenty women received triazolam (0.25 mg) or placebo at the follicular, ovulatory and luteal phases of their menstrual cycle. Each subject participated in six conditions (i.e., drug and placebo at each of the three phases), across two menstrual cycles. Dependent measures included self-reported mood states, psychomotor performance, and plasma levels of estradiol, progesterone, allopregnanolone, and triazolam. Mood and performance measures were not clearly related to hormone levels when data from all three phases were examined. However, within the luteal phase, higher levels of allopregnanolone were associated with lower self-reported arousal before any drug administration (i.e., at baseline). After administration of triazolam, most subjects reported the expected decreases in rating of arousal. However, the subjects with the highest levels of allopregnanolone reported increases in ratings of arousal. Thus, hormone levels were related to mood and responses to triazolam, particularly during the luteal phase of the cycle. However, the drug-hormone interactions on mood and behavior were complex.