Acute electronic cigarette use: nicotine delivery and subjective effects in regular users

Rationale

Electronic cigarettes are becoming increasingly popular among smokers worldwide. Commonly reported reasons for use include the following: to quit smoking, to avoid relapse, to reduce urge to smoke, or as a perceived lower-risk alternative to smoking. Few studies, however, have explored whether electronic cigarettes (e-cigarettes) deliver measurable levels of nicotine to the blood.

Objective

This study aims to explore in experienced users the effect of using an 18-mg/ml nicotine first-generation e-cigarette on blood nicotine, tobacco withdrawal symptoms, and urge to smoke.

Methods

Fourteen regular e-cigarette users (three females), who are abstinent from smoking and e-cigarette use for 12 h, each completed a 2.5 h testing session. Blood was sampled, and questionnaires were completed (tobacco-related withdrawal symptoms, urge to smoke, positive and negative subjective effects) at four stages: baseline, 10 puffs, 60 min of ad lib use and a 60-min rest period.

Results

Complete sets of blood were obtained from seven participants. Plasma nicotine concentration rose significantly from a mean of 0.74 ng/ml at baseline to 6.77 ng/ml 10 min after 10 puffs, reaching a mean maximum of 13.91 ng/ml by the end of the ad lib puffing period. Tobacco-related withdrawal symptoms and urge to smoke were significantly reduced; direct positive effects were strongly endorsed, and there was very low reporting of adverse effects.

Conclusions

These findings demonstrate reliable blood nicotine delivery after the acute use of this brand/model of e-cigarette in a sample of regular users. Future studies might usefully quantify nicotine delivery in relation to inhalation technique and the relationship with successful smoking cessation/harm reduction.     

Acute effects of nicotine and mecamylamine on tobacco withdrawal symptoms, cigarette reward and ad lib smoking

Separate and combined effects of nicotine and the nicotinic antagonist mecamylamine were studied in 32 healthy volunteer smokers after overnight abstinence from smoking. Subjects participated in three sessions (3 h each), during which they wore skin patches delivering either 0 mg/24 h, 21 mg/24 h or 42 mg/24 h nicotine. Thirty-two subjects were randomly assigned to two groups receiving oral mecamylamine hydrochloride (10 mg) vs. placebo capsules. Two and one-half hours after drug administration, subjects were allowed to smoke ad lib, rating the cigarettes for rewarding and aversive effects. Transdermal nicotine produced a dose-related reduction in the subjective rewarding qualities of smoking. Nicotine also reduced craving for cigarettes and this effect was attenuated, but not eliminated, by mecamylamine. Mecamylamine blocked the discriminability of high vs. low nicotine puffs of smoke, and increased nicotine intake substantially during the ad lib smoking period. Some of the psychophysiological effects of each drug (elevation in blood pressure from nicotine, sedation and decreased blood pressure from mecamylamine) were offset by the other drug. The results supported the hypothesis that nicotine replacement can alleviate tobacco withdrawal symptoms even in the presence of an antagonist such as mecamylamine. Mecamylamine did not precipitate withdrawal beyond the level associated with overnight cigarette deprivation, suggesting its effects were primarily due to offsetting the action of concurrently administered nicotine as opposed to blocking endogenous cholinergic transmission.     

Naltrexone alteration of acute smoking response in nicotine-dependent subjects

There are mixed results on the effects of opioid antagonists on acute nicotine response in humans. The present study examined the effects of a single dose of 50 mg oral naltrexone relative to placebo on smoking response in 22 chronic smokers during short-term nicotine abstinence, after acute smoking and subsequent smoking deprivation, and on smoking behavior in a choice paradigm. The results showed that naltrexone significantly reduced immediate postcigarette ratings of smoking craving and desire to smoke and increased light-headedness, dizziness, and head rush (ps < 0.05). Reductions in craving and smoking desire persisted during a subsequent 1 h nonsmoking interval. Naltrexone also was found to significantly reduce the total number of cigarettes smoked in the choice interval, which was supported by objective measures of both reduced CO and plasma nicotine levels (ps < 0.01). Exploratory analyses on potential individual difference factors revealed that smokers with the highest levels of craving during abstinence showed the most pronounced naltrexone attenuation of smoking response. The results support the continued exploration of naltrexone as an adjunct to smoking cessation, especially in identified smoker subgroups most sensitive to the effects of opioid antagonism.     

Smoking history, nicotine dependence, and changes in craving and mood during short-term smoking abstinence in alcohol dependent vs. control smokers

Objective

The goal of this study was to compare lifetime cigarette smoking, severity of nicotine dependence, and subjective effects of short-term tobacco abstinence in abstinent alcohol dependent (AD) and control smokers.

Method

AD (n = 119) and control (n = 55) ever-smokers were compared on tobacco use history and nicotine dependence. Negative affect and craving to smoke were examined in a subsample of currently smoking AD (N = 34) and control (N = 19) participants during a 6-h period of tobacco abstinence using the Profile of Mood States (POMS) and the Questionnaire on Smoking Urges-Brief (QSU-B).

Results

Although AD smokers did not differ from controls on heaviness of smoking, they were more likely to meet lifetime criteria for nicotine dependence. AD smokers also reported more withdrawal symptoms and were more likely to endorse withdrawal-related depressed mood during past smoking reduction or abstinence periods. During short-term abstinence, AD smokers were more likely to report high craving to smoke for negative affect relief within the first 150 min of tobacco abstinence, but did not differ from controls on overall craving to smoke or withdrawal-related negative affect on the POMS.

Conclusions

Results support previous findings that AD smokers have a greater prevalence of nicotine dependence and more severe nicotine withdrawal, with a greater propensity toward withdrawal-related depressed mood. These results, along with our novel finding that greater craving to smoke in abstaining smokers with AD is specific to negative affect-related craving, suggest that negative reinforcement may be a particularly salient factor in the maintenance of tobacco use among individuals with AD.     

High-dose transdermal nicotine and naltrexone: effects on nicotine withdrawal, urges, smoking, and effects of smoking

Although treatment with transdermal nicotine replacement (TNR) has improved smoking abstinence rates, higher doses of TNR could improve effects on urge to smoke, nicotine withdrawal, and reinforcement from smoking, and naltrexone might further reduce reinforcement and urges. A laboratory investigation with 134 smokers using a 3 x 2 parallel-group design evaluated the effects of TNR (42-mg, 21-mg, or 0-mg patch) as crossed with a single dose of naltrexone (50 mg) versus placebo on urge to smoke, withdrawal, and responses to an opportunity to smoke (intake, subjective effects) after 10 hr of deprivation. Urge and withdrawal were assessed both prior to and after cigarette cue exposure. Only 42 mg TNR, not 21 mg, prevented urge to smoke, heart rate change, and cue-elicited increase in withdrawal. Both 21 and 42 mg TNR blocked cue-elicited drop in heart rate and arterial pressure. Naltrexone reduced cue-elicited withdrawal symptoms but not urges to smoke or deprivation-induced withdrawal prior to cue exposure. Neither medication significantly affected carbon monoxide intake or subjective effects of smoking except that 42 mg TNR resulted in lower subjective physiological activation. No interaction effects were found, and no results differed by gender. Results suggest that starting smokers with 42 mg TNR may increase comfort during initial abstinence, but limited support is seen for naltrexone during smoking abstinence.     

Effect of glucose tablets on craving for cigarettes

Clients attending a smokers clinic were randomly allocated to two groups to assess the effects of glucose tablets in reducing craving for cigarettes. Smokers who had already been abstinent for 1 week were eligible to take part in the study. All subjects completed ratings relating to urge to smoke and craving. Then subjects in one group were given packets of dextrose tablets and those in the other group were given packets of tablets containing sorbitol (a low calorie sweetener). Ratings of urges to smoke and craving were taken after 1 week, during which time the subjects had been asked to chew their tablets ad lib. Eight out of ten smokers in each group maintained abstinence. The remaining two smokers either did not abstain or did not turn up for the second measurement session. There was a significant reduction in ratings of urges to smoke and craving in the glucose group compared with the sorbitol group. These results support a theory postulating a link between glucoregulation and cigarette craving. If the results are replicated and it is shown that the reduction in craving translates into improved abstinence rates, oral glucose could be of assistance to smokers wishing to give up.     

Leptin, hunger, and body weight: Influence of gender, tobacco smoking, and smoking abstinence

Leptin is a hormone involved in body weight and hunger regulation, and may contribute to the inverse relationship between cigarette smoking and body weight. Leptin levels, body mass indices (BMIs), and hunger ratings were determined in 22 nonsmokers (12 male, 10 female) and 19 cigarette smokers (11 male, 8 female). Smokers were tested after ad lib smoking and following a 24-h smoking abstinence period; nonsmokers came to the laboratory once. Leptin levels were not different among the groups. Hunger ratings, however, were higher after smoking abstinence compared to after ad lib smoking and nonsmokers (Ps<.05); levels of hunger did not differ between ad lib smokers and nonsmokers. Men reported higher hunger levels than did women, but women had higher serum leptin levels than did men, regardless of smoking condition (P<.05). Leptin levels were correlated with BMI (P<.05) among smokers only. This first study on leptin responses in female smokers suggests that leptin levels do not change following a 24-h smoking abstinence period and that leptin may not contribute to increased hunger following smoking abstinence.     

Sensory blockade of smoking satisfaction

Cigarette smokers were presented with controlled doses of cigarette smoke to determine whether the resulting reduction in cigarette craving depended upon perceiving the sensory qualities of the smoke. Cigarette craving was assessed before and after inhaling controlled doses of smoke in two conditions: (1) Local anesthesia of the upper and lower respiratory airways, induced by mouth rinsing, gargling and inhalation of a mist containing the topical anesthetic lidocaine; and (2) no-anesthesia control, in which all solutions were saline. A sham smoking procedure was presented in both conditions. Craving and ad lib smoking behavior were also assessed 30 minutes after controlled smoking. The results indicated that smoke, as opposed to sham puffs, significantly reduced reports of cigarette craving, and local anesthesia significantly blocked this immediate reduction in craving produced by smoke inhalation. Puffs were also rated as less desirable in the anesthesia condition. Thirty minutes after smoking, craving was no different in the anesthesia and saline control conditions. However, craving as well as smoking intake in both conditions was less when smoke had been given previously than in the sham smoking control. These results suggest that sensory cues accompanying inhalation of cigarette smoke are important determinants of immediate smoking satisfaction. However, the sustained effects of smoke intake on subsequent smoking behavior (30 min later) may be mediated by processes other than sensory stimulation of the respiratory tract, such as plasma nicotine levels.     

Cigarette smoking: Habit or nicotine maintenance? effects of short-term smoking abstinence and oversmoking

Cigarette consumption, craving to smoke and smoking pleasure, subjective reasons for smoking, heart rate, motor activity, and nutrient intake were continuously assessed in 22 subjects. After ad lib smoking on the first experimental day, subjects had to abstain between 12:30 h and 17:30 h on the second day and to smoke twice the habituated number of cigarettes during the same period of the third day. Craving and smoking pleasure decreased during oversmoking and increased for the first cigarettes after abstinence. Activity adjusted heart rates decreased by about 5 bpm during abstinence. In the evenings, however, these parameters as well as smoking rates, subjective reasons for smoking, and nutrient intake remained completely unaffected by the previous manipulations. Also cardiac nicotine tolerance, as assessed by the increases of the averaged activity-adjusted heart rates after cigarette lighting, was identical for all three evenings, irrespective of the afternoon smoking condition. Furthermore, none of the subjective effects of the afternoon abstinence was observed for the longer lasting overnight deprivation. These results suggest that habituated temporal patterns play a role in cigarette smoking which is perhaps even more important than the need to maintain a constant plasma nicotine level.     

Nicotine and Non-Nicotine Smoking Factors Differentially Modulate Craving,Withdrawal and Cerebral Blood Flow as Measured with Arterial Spin Labeling

Smoking cessation results in withdrawal symptoms such as craving and negative mood that may contribute to lapse and relapse. Little is known regarding whether these symptoms are associated with the nicotine or non-nicotine components of cigarette smoke. Using arterial spin labeling, we measured resting-state cerebral blood flow (CBF) in 29 adult smokers across four conditions: (1) nicotine patch+denicotinized cigarette smoking, (2) nicotine patch+abstinence from smoking, (3) placebo patch+denicotinized cigarette smoking, and (4) placebo patch+abstinence from smoking. We found that changes in self-reported craving positively correlated with changes in CBF from the denicotinized cigarette smoking conditions to the abstinent conditions. These correlations were found in several regions throughout the brain. Self-reported craving also increased from the nicotine to the placebo conditions, but had a minimal relationship with changes in CBF. The results of this study suggest that the non-nicotine components of cigarette smoke significantly impact withdrawal symptoms and associated brain areas, independently of the effects of nicotine. As such, the effects of non-nicotine factors are important to consider in the design and development of smoking cessation interventions and tobacco regulation.     

Delay discounting and the behavioural economics of cigarette purchases in smokers: the effects of nicotine deprivation

RATIONALE: In smokers, nicotine deprivation may increase impulsive decision-making and the demand for cigarettes. OBJECTIVES: To investigate the effects of acute nicotine deprivation on (a) the delay discounting of monetary and cigarette rewards, and (b) the behavioural economics of hypothetical cigarette purchases. MATERIALS AND METHODS: A repeated measures design was employed, with participants (daily cigarette smokers, N=30) repeating experimental tasks in two different sessions, once after at least 13 h of abstinence from smoking and once after ad lib smoking. Participants completed measures of cigarette craving, impulsivity, delay discounting and a behavioural economic simulation in which participants made hypothetical purchases of cigarettes and other commodities as the price of cigarettes was systematically varied. RESULTS: Participants showed more pronounced delay discounting of both cigarette and monetary rewards after abstinence compared to after ad lib smoking. In the behavioural economic simulation, nicotine deprivation had no influence on hypothetical cigarette purchases. However, spending on some commodities (alcohol, clothing, household goods, leisure activities and long-distance travel) was reduced as the price of cigarettes increased in order to fund increased spending on cigarettes, although the number of packs of cigarettes purchased actually decreased. CONCLUSIONS: Nicotine deprivation increases impulsive choices for both cigarette and monetary rewards in a delay-discounting task. Results from a behavioural economic simulation suggest that increases in the price of cigarettes may increase smokers' spending on cigarettes, while also reducing the number of cigarettes purchased.     

The effect of bupropion on nicotine craving and withdrawal

Rationale and objectives: Bupropion has demonstrated efficacy for smoking cessation. Given the importance of nicotine craving and withdrawal in the smoking cessation process, the current study examined the effects of bupropion on these parameters during smoking abstinence. Methods: During a 2-day Baseline phase with ad lib smoking, 91 non-depressed smokers (who were not trying to quit permanently) were administered measures of nicotine craving, withdrawal symptoms, and timed measures of cognitive performance five times daily. Participants were then assigned randomly to a 14-day treatment regimen with bupropion 300 mg/day, bupropion 150 mg/day, or placebo. Thereafter, the above measures were re-administered during 3 days of abstinence on a closed research ward. Results: Relative to placebo, 300 mg bupropion significantly reduced abstinence-associated increases in rated depression, difficulty concentrating, and irritability, and attenuated a decrease in positive affect. The results also suggested that bupropion might have a positive effect on performance measures during the withdrawal period. No effects were observed on craving, anxiety, restlessness, or hunger. The lack of findings on craving measures may be explained by a floor effect; except on the first day of abstinence, neither drug nor placebo groups showed much craving elevation during abstinence. Conclusions: Study results indicate that bupropion ameliorates some nicotine withdrawal symptoms. Received: 24 February 1999 / Final version: 15 August 1999     

Sweet taste preference in women smokers: Comparison with nonsmokers and effects of menstrual phase and nicotine abstinence

Cigarette smokers weigh less than comparably aged nonsmokers, and many gain weight following cessation. Though some evidence suggests that nicotine reduces food intake, with a selective effect on sweet-tasting foods, the issue remains unresolved. In the current study, 64 women (20 smokers, 26 never-smokers, and 18 ex-smokers) were tested for sweet taste preference; 9 of these smokers were studied under conditions of both ad lib smoking and overnight abstinence, in three hormonally verified menstrual phases. 1) Although no overall differences were detected in taste preference among the three groups, significantly more smokers than nonsmokers preferred the higher sucrose concentrations. 2) No significant differences due to menstrual phase were observed. 3) Although preference ratings did not differ significantly between overnight abstinence and ad lib smoking, a subset of smokers who preferred higher sucrose concentrations rated their preference for the solutions significantly higher during the ad lib smoking sessions. Our findings suggest that smoking and nonsmoking women differ with respect to taste preference and that, at least in a subset of female smokers, preference is affected by nicotine abstinence/acute dosing.     

Smokers deprived of cigarettes for 72 h: effect of nicotine patches on craving and withdrawal

Abstract Rationale. Research on the effects of nicotine abstinence and nicotine replacement has not provided consistent information about the impact of replacement therapies on tobacco withdrawal and craving. Objective. This study investigated craving and withdrawal symptoms over a 72-h period of abstinence from cigarettes. Methods. Twenty-four healthy volunteers, not intending to quit smoking, were housed in an experimental unit during three 72-h conditions, consisting of either free smoking, enforced smoking cessation with nicotine replacement therapy (NRT) patches, or enforced smoking cessation with placebo patches. The conditions were adhered to using a randomized crossover design, each separated by at least 10 days of washout. Patches, administered in a double-blind fashion, were given as nicotine (21 mg/24 h) and placebo every 24 h. Self-reported cigarette craving and withdrawal were assessed using multi-item scales at fixed intervals over each condition period. Urinary and plasma cortisol levels were also assayed at fixed intervals over each period. Results. Craving intensity was significantly lower with free smoke than with placebo and with NRT patches than with placebo. No difference in craving levels was found between those who smoked or those who had NRT patches. Withdrawal symptoms were significantly lower with free smoke than with either placebo or NRT patches, but there was no difference in levels of withdrawal between those on NRT patches and those on placebo. During the placebo and NRT patch periods, craving intensity displayed a circadian rhythm, with craving levels lowest in the morning and peaking in the evening. Nicotine delivered via the patch had no impact on these circadian variations in craving. There was no evidence of systematic temporal variations in craving levels during the free smoking period. Conclusions. The data suggested that craving and withdrawal symptoms may be sustained by different physiological pathways, and that only selected components of cigarette craving are influenced by NRT. Electronic Publication     

Psychophysiological effects of nicotine abstinence and behavioral challenges in habitual smokers

We tested the hypothesis that psychophysiological responses to behavioral challenges are enhanced by short-term abstinence from smoking. Blood pressure (BP), salivary cortisol levels, and withdrawal symptoms were measured after a period of smoking abstinence (18 h) or ad libitum smoking, during rest, and in response to acute behavioral challenges. Thirty habitual smokers (15 women and 15 men) participated in two laboratory sessions conducted on two separate days (after abstinence or ad libitum smoking). Cotinine concentrations in saliva and expired carbon monoxide were measured in both conditions. Abstinence produced significant withdrawal symptoms in all participants, with women reporting greater desire to smoke than men. Participants showed greater systolic BP responses to the behavioral challenges in the abstinence condition than the control condition. They also showed worse cognitive performance on the challenges in the abstinence than in the ad libitum condition. Men had greater salivary cortisol levels than women, and both men and women showed the expected decline in cortisol levels across time, but showed no difference between the abstinence and ad libitum smoking conditions in the laboratory or during ambulatory measurements. These results indicate that abstinence alters mood, performance, and BP responses to acute challenges but not adrenocortical responses. It is possible that these changes mediate stress-related vulnerability to smoking relapse.     

Dissociating nicotine and nonnicotine components of cigarette smoking

To dissociate the sensorimotor aspects of cigarette smoking from the pharmacologic effects of nicotine, smokers rated the subjective effects of nicotine-containing or denicotinized cigarettes, and intravenous (IV) nicotine or saline infusions. Three groups of participants (n=20 per group) received either: (1) continuous nicotine, (2) pulsed nicotine, or (3) saline. Each group was exposed to an IV condition once while smoking a denicotinized cigarette and once while not smoking, in a 3x2 mixed design. A fourth group (n=20) received saline while smoking their usual brand of cigarette. The dose and rate of nicotine administration were individualized based on previous measures of ad lib smoke intake. Denicotinized cigarette smoke significantly reduced craving and was rated significantly more satisfying and rewarding than the no-smoking conditions. IV nicotine reduced craving for cigarettes, and increased ratings of lightheadedness and dizziness. However, no significant satisfaction or reward was reported after IV nicotine. The combination of IV nicotine and denicotinized cigarette smoke produced effects similar to those of smoking the usual brand of cigarette. The results suggest that sensorimotor factors are critical in mediating the immediate subjective response to smoking, and that the immediate subjective effects of nicotine administered in doses obtained from cigarette smoking are subtle. Thus, addressing smokers' needs for both for the sensorimotor aspects of smoking as well as for the direct CNS effects of nicotine may be critical in enhancing smoking cessation treatment outcome.     

Pre-abstinence smoke intake and smoking motivation as predictors of severity of cigarette withdrawal symptoms

Twenty-nine cigarette smokers completed a smoking motivation questionnaire and had expired-air carbon monoxide (CO) and plasma nicotine concentrations measured prior to abstaining from smoking for 24 h. Before and after the abstinence period, the subjects rated mood and physical symptoms known to be affected by cigarette abstinence (e.g. irritability, restlessness). Scores on the dependent smoking subscale of the smoking motivation questionnaire correlated significantly with overall withdrawal severity, craving, and increased irritability. Indulgent smoking scores correlated positively with increased hunger. Pre-abstinence plasma nicotine concentration significantly pedicted craving, hunger, restlessness, inability to concentrate and overall withdrawal severity, while expired-air CO predicted craving and restlessness only. Usual daily cigarette consumption did not significantly predict any withdrawal effects. The data indicate that pre-abstinence measures of smoking motivation and smoke intake may provide a guide to withdrawal severity on smoking cessation and that smokers with a high pre-abstinence nicotine intake experience the greatest discomfort.     

Effects of nicotine on methadone self-administration in humans

The effects of nicotine abstinence, ad libitum smoking, and 0, 2, and 4 mg nicotine gum on methadone self-administration were investigated. Five methadone-maintained patients with a history of smoking (18–30 cigarettes/day) were recruited as subjects. Upon arrival expired carbon monoxide levels were measured to confirm self-reported abstinence of 10–12 h. At 30 min prior to the methadone self-administration session, two response options were concurrently available. When a 64-button press requirement (FR64) was completed, 10 ml of 0.054 mg/ml methadone solution, or vehicle, was delivered. Immediately following, and 30, 60, 90, and 120 min after the self-administration session, expired carbon monoxide levels and typical symptoms of nicotine withdrawal were assessed. Relative to abstinence, subjects consumed more methadone following the 4-mg nicotine gum and ad libitum smoking conditions. Ratings of cigarette craving were significantly less following ad libitum smoking or administration of 4-mg nicotine gum, than following abstinence. Implications for understanding opioid and nicotine interactions are discussed.     

Reduction of abstinence-induced withdrawal and craving using high-dose nicotine replacement therapy

Rationale Decreasing withdrawal and craving during smoking cessation is a major aim of cessation medications. Prior studies have shown that Nicotine Replacement Therapy (NRT) decreases withdrawal symptom severity but have relied on retrospective reports and lacked robust measures of baseline symptoms or symptoms during unmedicated abstinence. Objectives and methods We tested the effect of high-dose (35 mg) nicotine patch on withdrawal and craving during abstinence using real-time assessment with electronic diaries during ad libitum smoking, a brief period of experimentally directed trial abstinence, and the first 3 days of cessation. Subjects were 324 smokers randomized to high-dose nicotine patches or placebo. Results Treatment with active patches reduced withdrawal and craving during cessation and completely eliminated deprivation-related changes in affect or concentration. Conclusion High-dose NRT reduces withdrawal symptoms and craving and can eliminate some symptoms entirely. Saul Shiffman and Stuart Ferguson consult exclusively for GlaxoSmithKline Consumer Healthcare on matters relating to existing smoking cessation products. Dr. Shiffman also has an interest in a new smoking cessation product, and is a founder of invivodata, inc., which provides electronic diaries for clinical trials.     

Effects of selegiline (l-deprenyl) during smoking and short-term abstinence

RATIONALE: Changes in dopamine level are thought to play an important role in both smoking reward and withdrawal symptoms during abstinence. Medications that modulate dopamine levels may have beneficial effects on both withdrawal symptom levels and on response to smoking lapses during abstinence. OBJECTIVES: To examine the effects of the selective MAO-B inhibitor selegiline on withdrawal symptoms, smoking behavior and smoking satisfaction ratings. METHODS: Fifteen smokers received selegiline (10 mg/day) and placebo (in counterbalanced order) on Monday through Thursday of 2 study weeks, separated by a 2-week washout. During each study week, ad lib smoking sessions were scheduled to assess smoking behavior both before and after a brief period of abstinence. Subjective withdrawal symptoms and mood were measured daily, and a modified Stroop test sensitive to withdrawal was scheduled during the period of abstinence. RESULTS: Selegiline decreased craving, especially during abstinence, and impaired performance on the modified Stroop test during subjects' attempts to abstain. Medication also reduced number of cigarettes smoked and smoking satisfaction ratings during the smoking sessions both before and after the brief abstinence attempt. CONCLUSION: These results are consistent with an important role of dopamine in smoking behavior and abstinence. They suggest that pharmacological reduction of MAO-B levels during the early part of a quit attempt may aid in smoking cessation.