Acute effects of D-amphetamine on progressive-ratio performance maintained by cigarette smoking and money

An observational human laboratory assessment of nicotine delivery, vaping topography and subjective effects of usual brand electronic cigarette use among young adults

AIMS

To measure nicotine delivery, vaping topography and subjective effects of current generations of disposable, cartridge-based and other types of electronic cigarettes (e-cigarettes) among young adults.

DESIGN, SETTING, PARTICIPANTS

Observational, human laboratory assessment of e-cigarette use in Columbus, Ohio, USA (July 2020 to June 2021). Participants (n = 96, 60.4% female, age mean = 21.7 [standard deviation = 1.7] years, 82.4% white race) were identified via their participation in a cohort study or other convenience sampling and were 18 to 25 years old, vaped ≥4 days/week for ≥4 weeks and used other tobacco products for ≤5 days of past 30 days. Participants completed a pre-vaping questionnaire, vaped their usual brand of e-cigarette ad libitum for 30 min and completed a post-vaping questionnaire.

MEASUREMENTS

Outcome variables included pre- and post-vaping measures of plasma nicotine (t = 0 and t = 30, respectively) and craving and withdrawal symptoms, as well as vaping topography (e.g. flow rate and inter-puff interval), pre-vaping expectancies and post-vaping product appeal. Variables used to characterize the sample included demographics, e-cigarette and other tobacco use history, e-cigarette dependence and e-cigarette device characteristics (e.g. device type, flavor and nicotine form).

FINDINGS

Participants reported moderate nicotine dependence on average via the E-Cigarette Dependence Scale (mean = 6.9 [standard deviation = 4.0]). Following 30 min of ad libitum vaping, participants achieved substantial plasma nicotine boost (mean = 18.8 [standard deviation = 14.5] ng/mL), corresponding with statistically significant decreases in withdrawal symptoms measured via the Minnesota Nicotine Withdrawal Scale (pre-vaping mean = 9.0 [standard deviation = 5.1], post-vaping mean = 4.3 [standard deviation = 3.9]; P-value <0.0001). Pre-vaping, participants reported moderate vaping expectancies (e.g. mean = 2.5 [standard deviation = 1.0] on a scale from 0 to 4 for smell and taste expectancies); post-vaping, participants reported high satisfaction (mean = 4.6 [standard deviation = 1.2] on a scale from 1 to 7) and moderate reward (mean = 2.9 [standard deviation = 1.2]) and respiratory sensations (mean = 3.7 [standard deviation = 1.6]). Nearly half of participants (47.9%) used disposable e-cigarettes, and most used a mint/menthol or fruit flavored (99.0%) and nicotine salt (98.9%) e-liquid.

CONCLUSIONS

Among young adults in the United States, the latest generations of e-cigarettes appear to deliver large quantities of nicotine (similar to cigarettes) and significantly relieve withdrawal symptoms, and they are appealing.

Nicotine modifies cocaine responding in a concurrent self-administration model

BACKGROUND

Preclinical models of cocaine use disorder (CUD) have not yielded any FDA-approved pharmacotherapies, potentially due to a focus on cocaine use in isolation, which may not fully translate to real-world drug taking patterns. Cocaine and nicotine are commonly used together, and clinical research suggests that nicotine may increase the potency and reinforcing strength of cocaine. In this study, we sought to determine whether and how the addition of nicotine would alter ongoing intravenous cocaine self-administration and motivation to take cocaine in rats.

METHODS

Male Sprague-Dawley rats self-administered cocaine alone on a long access, Fixed Ratio one (FR1) schedule, and then switched to a combination of cocaine and nicotine. Finally, rats responded on a Progressive Ratio (PR) schedule for several doses of cocaine alone and in combination with a single dose of nicotine.

RESULTS

Under long access conditions, rats co-self-administering cocaine and nicotine responded less and with decreased response rates than for cocaine alone and did not escalate responding. However, under PR conditions that test motivation to take drugs, the dose response curve for the combination was shifted upwards relative to cocaine alone.

CONCLUSIONS

Together, these results suggest that nicotine may enhance the reinforcing strength of cocaine, increasing PR responding for cocaine across the dose response curve.

Concurrent Choice Assessment of Preference and Substitutability of E-cigarettes and Heated Tobacco Products for Combustible Cigarettes Among African American and White Smokers

INTRODUCTION

Alternative nicotine delivery products, including electronic cigarettes (e-cigarettes) and heated tobacco products (HTPs), contain fewer toxicants than combustible cigarettes and offer a potential for harm reduction. Research on the substitutability of e-cigarettes and HTPs is crucial for understanding their impact on public health. This study examined subjective and behavioral preferences for an e-cigarette and HTP relative to participants' usual brand combustible cigarette (UBC) in African American and White smokers naïve to alternative products.

AIMS AND METHODS

Twenty-two adult African American (n = 12) and White (n = 10) smokers completed randomized study sessions with their UBC and study provided e-cigarette and HTP. A concurrent choice task allowed participants to earn puffs of the products but placed UBC on a progressive ratio schedule, making puffs harder to earn, and e-cigarette and HTP on a fixed ratio schedule to assess behavioral preference for the products. Behavioral preference was then compared to self-reported subjective preference.

RESULTS

Most participants had a subjective preference for UBC (n = 11, 52.4%), followed by an equal preference for e-cigarette (n = 5, 23.8%) and HTP (n = 5, 23.8%). During the concurrent choice task, participants showed a behavioral preference (i.e., more earned puffs) for the e-cigarette (n = 9, 42.9%), followed by HTP (n = 8, 38.1%), and UBC (n = 4, 19.1%). Participants earned significantly more puffs of the alternative products compared to UBC (p = .011) with no difference in earned puffs between e-cigarettes and HTP (p = .806).

CONCLUSIONS

In a simulated lab setting, African American and White smokers were willing to substitute UBC for an e-cigarette or HTP when the attainment of UBC became more difficult.

TRIAL REGISTRATION

NCT04646668.

IMPLICATIONS

Findings suggest that African American and White smokers are willing to substitute their UBC for an alternative nicotine delivery product (e-cigarette or HTP) when the attainment of cigarettes became more difficult in a simulated lab setting. Findings require confirmation among a larger sample under real-world conditions but add to growing evidence suggesting the acceptability of alternative nicotine delivery products among racially diverse smokers. These data are important as policies that limit the availability or appeal of combustible cigarettes are considered or enacted.

The co-use of nicotine and prescription psychostimulants: A review of their behavioral and neuropharmacological interactions

BACKGROUND

Nicotine is commonly co-used with other psychostimulants. These high co-use rates have prompted much research on interactions between nicotine and psychostimulant drugs. These studies range from examination of illicitly used psychostimulants such as cocaine and methamphetamine to prescription psychostimulants used to treat attention deficit hyperactivity disorder (ADHD) such as methylphenidate (Ritalin™) and d-amphetamine (active ingredient of Adderall™). However, previous reviews largely focus on nicotine interactions with illicitly used psychostimulants with sparse mention of prescription psychostimulants. The currently available epidemiological and laboratory research, however, suggests high co-use between nicotine and prescription psychostimulants, and that these drugs interact to modulate use liability of either drug. The present review synthesizes epidemiological and experimental human and pre-clinical research assessing the behavioral and neuropharmacological interactions between nicotine and prescription psychostimulants that may contribute to high nicotine-prescription psychostimulant co-use.

METHODS

We searched databases for literature investigating acute and chronic nicotine and prescription psychostimulant interactions. Inclusion criteria were that participants/subjects had to experience nicotine and a prescription psychostimulant compound at least once in the study, in addition to assessment of their interaction.

RESULTS AND CONCLUSIONS

Nicotine clearly interacts with d-amphetamine and methylphenidate in a variety of behavioral tasks and neurochemical assays assessing co-use liability across preclinical, clinical, and epidemiological research. The currently available research suggests research gaps examining these interactions in women/female rodents, in consideration of ADHD symptoms, and how prescription psychostimulant exposure influences later nicotine-related outcomes. Nicotine has been less widely studied with alternative ADHD pharmacotherapy bupropion, but we also discuss this research.

E-cigarettes may serve as a gateway to conventional cigarettes and other addictive drugs

Electronic cigarettes (e-cigarettes) are devices that allow the user to inhale nicotine in a vapor, and are primarily marketed as a means of quitting smoking and a less harmful replacement for traditional cigarette smoking. However, further research is needed to determine if vaping nicotine via e-cigarettes can be effective. Conversely, nicotine has been considered a gateway drug to alcohol and other addictive drugs and e-cigarettes containing nicotine may have the same effects. Previous reports have shown that e-cigarette use may open the gate for the use of other drugs including conventional cigarettes, cannabis, opioids, etc. The increasing prevalence of e-cigarettes, particularly among youth and adolescents in the last decade have led to an increase in the dual use of e-cigarettes with alcohol, cannabis, and other illicit drug use like heroin and 3-4-methylenedioxymethamphetamine (MDMA). The advent of e-cigarettes as a device to self-administer addictive agents such as cocaine and synthetic cathinones may bring about additional adverse health effects associated with their concurrent use. This review aims to briefly describe e-cigarettes and their different generations, and their co-use with other addictive drugs as well as the use of the device as a tool to self-administer addictive drugs, such as cocaine, etc.

Investigating sex differences and the effect of drug exposure order in the sensory reward-enhancing effects of nicotine and d-amphetamine alone and in combination

Nicotine enhances the rewarding effects of other environmental stimuli; this reward-enhancement encourages and maintains nicotine consumption. Nicotine use precedes other psychostimulant use, but receiving a stimulant prescription also predicts future smoking. Previously, no study has investigated effects of drug exposure order in reward-enhancement, nor with nicotine and d-amphetamine. Thus, we aimed to investigate how drug exposure order impacted the reward-enhancing effects of nicotine and d-amphetamine, alone and in combination. We used 20 male and 20 female Sprague-Dawley rats. Enhancement was investigated within-subjects by examining responding maintained by a visual stimulus reinforcer following a pre-session injection of either d-amphetamine (Sal, 0.1, 0.3, or 0.6 mg/kg) or nicotine (Sal, 0.03, 0.06, 0.1, 0.3 mg/kg). Twenty rats (10 M, 10 F) completed enhancement testing with nicotine before d-amphetamine. The other 20 rats (10 M, 10 F) completed testing with d-amphetamine before nicotine. Following these phases, rats were then given two pre-session injections: one of d-amphetamine (Sal, 0.1, 0.3, or 0.6 mg/kg) and another of nicotine (Sal, 0.03, 0.06, 0.1, or 0.3 mg/kg). Experiencing amphetamine before nicotine increased reward-enhancing effects of nicotine. Females exhibited greater effects of d-amphetamine on reward-enhancement, with no effect of exposure order. During the interaction phase, receiving nicotine before amphetamine enhanced the interaction between nicotine and d-amphetamine for females whereas amphetamine before nicotine heightened this interaction for males. From this, prior and current amphetamine use, in addition to sex, should be considered when treating nicotine dependency and when examining factors driving poly-substance use involving nicotine and d-amphetamine. Keywords: Adderall, ADHD, Dexedrine, operant, smoking, polysubstance use.

Reward-enhancing effects of d-amphetamine and its interactions with nicotine were greater in female rats and persisted across schedules of reinforcement

Nicotine enhances the value of environmental stimuli and rewards, and reward enhancement can maintain nicotine consumption. Stimulants such as d-amphetamine are misused more by women and are commonly co-used with nicotine. d-Amphetamine potentiates nicotine's effects in human and animal research. To date, there are no published studies examining this interaction in a reward-enhancement task. The current study sought to investigate the reward-enhancing effects of nicotine alongside and coadministered with d-amphetamine. Further, we evaluated the persistence of reward enhancement across ratio and temporal schedules of reinforcement. We used 10 male and 10 female Sprague-Dawley rats. Enhancement was assessed within subjects by examining active lever pressing for a visual stimulus reinforcer on variable ratio 3, variable interval 30 s and variable time 30 s - variable ratio 3 schedules. Before 1-h sessions, rats received one injection of saline, 0.1 or 0.3 mg/kg d-amphetamine and one of saline or 0.4 mg/kg nicotine, making six possible drug combinations (saline + saline, saline + nicotine, 0.1 d-amphetamine + aline, 0.1 d-amphetamine + nicotine, 0.3 d-amphetamine + saline and 0.3 d-amphetamine + nicotine) experienced in a randomized order by each rat. When d-amphetamine was coadministered with nicotine, we found an interaction effect on reward enhancement that persisted across schedules of reinforcement. Males and females exhibited reward enhancement by 0.3 d-amphetamine, while only females showed reward enhancement by 0.1 d-amphetamine. Further, females responded more for the visual stimulus than males in all d-amphetamine conditions. Future studies should assess how reward enhancement is involved in high nicotine-amphetamine comorbidity rates and enhanced amphetamine misuse in women.

Examining Age as a Potential Moderator of Response to Reduced Nicotine Content Cigarettes in Vulnerable Populations

Introduction

Young adults (aged 18–24 years) have a higher smoking prevalence than younger and older age groups and young adulthood is an important developmental period during which long-term behavior patterns like cigarette smoking are established. The aim of the current study was to examine how young adult smokers with additional vulnerabilities to smoking respond to reduced nicotine content cigarettes.

Methods

This is a secondary analysis of a double-blind, within-subject experiment conducted with 169 cigarette smokers recruited from populations with comorbid psychiatric conditions or socioeconomic disadvantage assessing acute effects of research cigarettes varying in nicotine content (0.4, 2.4, 5.2, 15.8 mg/g). Participants were dichotomized by chronological age (18–24 vs. ≥25 years). Across 14 laboratory sessions effects of nicotine content were examined on measures of relative reinforcing efficacy (Cigarette Purchase Task [CPT] and Concurrent Choice testing), subjective effects, craving/withdrawal, and smoking topography. Repeated measures analysis of variances were used to examine potential moderating effects of age.

Results

Young adults exhibited lower demand for reduced nicotine content cigarettes than older adults across three of five CPT indices (ps < .05). No differences by age were observed on other measures of reinforcing efficacy, subjective effects, craving/withdrawal, or smoking topography where effects generally decreased as an orderly function of decreasing nicotine content (ps <.05).

Conclusion

Overall, these findings suggest that reducing the nicotine content of cigarettes would decrease the addiction potential of cigarette smoking in young adult smokers as much or perhaps more than older adult smokers from populations at increased vulnerability to smoking, addiction, and smoking-related health consequences.

Implications

Reducing the nicotine content in cigarettes to lower addiction potential of smoking has been proposed as a means to improve overall population health. It is imperative to examine how young adults may respond to a nicotine reduction policy. We saw minimal evidence that age moderates acute response and where there was evidence it was in the direction of reduced nicotine content cigarettes having less addictive potential among young versus older adults (eg, steeper decreases in demand for very low nicotine content cigarettes among young versus older adults). Overall, a nicotine reduction policy has the potential to reduce smoking across age groups.

Examining effects of unit price on preference for reduced nicotine content cigarettes and smoking rate

Cigarette preference increases as a function of greater nicotine content, but manipulating cost can shift preference. The aims of the present study are to model whether (1) the behavioral-economic metric unit price (cost/reinforcer magnitude) accounts for preference shifts and (2) whether preference shifts toward reduced nicotine content are associated with smoking reductions. In a multisite study between 2015 and 2016, 169 daily smokers from vulnerable populations completed two concurrent-choice conditions examining preference for smoking normal (15.8 mg/g) and reduced (0.4 mg/g) nicotine content cigarettes. In Condition 1, both products were available at 10 responses/choice. In Condition 2, availability of the 0.4 mg/g dose remained at 10 responses/choice while the 15.8 mg/g dose was available on a progressive-ratio (PR) schedule wherein response cost increased following each choice. Unit prices were calculated by dividing dose by response requirement. Results were analyzed using ANOVA and binomial tests (p < .05). Participants preferred the 15.8 over 0.4 mg/g dose in Condition 1, but shifted preference to the 0.4 mg/g dose in Condition 2 (p < .001) immediately before the point in the PR progression where unit price for 15.8 dose exceeded unit price for the 0.4 dose (p < .001). This shift was associated with a reduction in smoking (p < .001). The unit price of nicotine appears to underpin cigarette product preference and may provide a metric for predicting preference and potentially impacting it through tobacco regulations. These results also demonstrate that reduced compared to normal nicotine content cigarettes sustain lower smoking rates discernible even under acute laboratory conditions and in vulnerable populations.

Response to reduced nicotine content cigarettes among smokers differing in tobacco dependence severity

This study examines whether tobacco dependence severity moderates the acute effects of reducing nicotine content in cigarettes on the addiction potential of smoking, craving/withdrawal, or smoking topography. Participants (N = 169) were daily smokers with mild, moderate, or high tobacco-dependence severity using the Heaviness of Smoking Index. Following brief abstinence, participants smoked research cigarettes varying in nicotine content (0.4, 2.4, 5.2, 15.8 mg nicotine/g tobacco) in a within-subject design. Results were analyzed using repeated measures analysis of co-variance. No main effects of dependence severity or interactions with nicotine dose were noted in relative reinforcing effects in concurrent choice testing or subjective effects on the modified Cigarette Evaluation Questionnaire. Demand for smoking in the Cigarette Purchase Task was greater among more dependent smokers, but reducing nicotine content decreased demand independent of dependence severity. Dependence severity did not significantly alter response to reduced nicotine content cigarettes on the Minnesota Tobacco Withdrawal Scale nor Questionnaire of Smoking Urges-brief (QSU) Factor-2 scale; dependence severity and dose interacted significantly on the QSU-brief Factor-1 scale, with reductions dependent on dose among highly but not mildly or moderately dependent smokers. Dependence severity and dose interacted significantly on only one of six measures of smoking topography (i.e., maximum flow rate), which increased as dose increased among mildly and moderately but not highly dependent smokers. These results suggest that dependence severity has no moderating influence on the ability of reduced nicotine content cigarettes to lower the addiction potential of smoking, and minimal effects on relief from craving/withdrawal or smoking topography.

Exploring longitudinal course and treatment-baseline severity interactions in secondary outcomes of smoking cessation treatment in individuals with attention-deficit hyperactivity disorder

BACKGROUND

A double blind, placebo-controlled randomized trial (NCT00253747) evaluating osmotic-release oral system methylphenidate (OROS-MPH) for smoking-cessation revealed a significant interaction effect in which participants with higher baseline ADHD severity had better abstinence outcomes with OROS-MPH while participants with lower baseline ADHD severity had worse outcomes.

OBJECTIVES

This current report examines secondary outcomes that might bear on the mechanism for this differential treatment effect.

METHODS

Longitudinal analyses were conducted to evaluate the effect of OROS-MPH on three secondary outcomes (ADHD symptom severity, nicotine craving, and withdrawal) in the total sample (N = 255, 56% Male), and in the high (N = 134) and low (N = 121) baseline ADHD severity groups.

RESULTS

OROS-MPH significantly improved ADHD symptoms and nicotine withdrawal symptoms in the total sample, and exploratory analyses showed that in both higher and lower baseline severity groups, OROS-MPH statistically significantly improved these two outcomes. No effect on craving overall was detected, though exploratory analyses showed statistically significantly decreased craving in the high ADHD severity participants on OROS-MPH. No treatment by ADHD baseline severity interaction was detected for the outcomes.

CONCLUSIONS

Methylphenidate improved secondary outcomes during smoking cessation independent of baseline ADHD severity, with no evident treatment-baseline severity interaction. Our results suggest divergent responses to smoking cessation treatment in the higher and lower severity groups cannot be explained by concordant divergence in craving, withdrawal and ADHD symptom severity, and alternative hypotheses may need to be identified.

Addiction Potential of Cigarettes With Reduced Nicotine Content in Populations With Psychiatric Disorders and Other Vulnerabilities to Tobacco Addiction

IMPORTANCE

A national policy is under consideration to reduce the nicotine content of cigarettes to lower nicotine addiction potential in the United States.

OBJECTIVE

To examine how smokers with psychiatric disorders and other vulnerabilities to tobacco addiction respond to cigarettes with reduced nicotine content.

DESIGN, SETTING, AND PARTICIPANTS

A multisite, double-blind, within-participant assessment of acute response to research cigarettes with nicotine content ranging from levels below a hypothesized addiction threshold to those representative of commercial cigarettes (0.4, 2.3, 5.2, and 15.8 mg/g of tobacco) at 3 academic sites included 169 daily smokers from the following 3 vulnerable populations: individuals with affective disorders (n = 56) or opioid dependence (n = 60) and socioeconomically disadvantaged women (n = 53). Data were collected from March 23, 2015, through April 25, 2016.

INTERVENTIONS

After a brief smoking abstinence, participants were exposed to the cigarettes with varying nicotine doses across fourteen 2- to 4-hour outpatient sessions.

MAIN OUTCOMES AND MEASURES

Addiction potential of the cigarettes was assessed using concurrent choice testing, the Cigarette Purchase Task (CPT), and validated measures of subjective effects, such as the Minnesota Nicotine Withdrawal Scale.

RESULTS

Among the 169 daily smokers included in the analysis (120 women [71.0%] and 49 men [29.0%]; mean [SD] age, 35.6 [11.4] years), reducing the nicotine content of cigarettes decreased the relative reinforcing effects of smoking in all 3 populations. Across populations, the 0.4-mg/g dose was chosen significantly less than the 15.8-mg/g dose in concurrent choice testing (mean [SEM] 30% [0.04%] vs 70% [0.04%]; Cohen d = 0.40; P < .001) and generated lower demand in the CPT (α = .027 [95% CI, 0.023-0.031] vs α = .019 [95% CI, 0.016-0.022]; Cohen d = 1.17; P < .001). Preference for higher over lower nicotine content cigarettes could be reversed by increasing the response cost necessary to obtain the higher dose (mean [SEM], 61% [0.02%] vs 39% [0.02%]; Cohen d = 0.40; P < .001). All doses reduced Minnesota Nicotine Withdrawal Scale total scores (range of mean decreases, 0.10-0.50; Cohen d range, 0.21-1.05; P < .001 for all), although duration of withdrawal symptoms was greater at higher doses (η2 = 0.008; dose-by-time interaction, P = .002).

CONCLUSIONS AND RELEVANCE

Reducing the nicotine content of cigarettes may decrease their addiction potential in populations that are highly vulnerable to tobacco addiction. Smokers with psychiatric conditions and socioeconomic disadvantage are more addicted and less likely to quit and experience greater adverse health impacts. Policies to reduce these disparities are needed; reducing the nicotine content in cigarettes should be a policy focus.

Anhedonia Is Associated with Poorer Outcomes in Contingency Management for Cocaine Use Disorder

This study explored anhedonia (lack of interest or pleasure in non-drug rewards) as a potentially modifiable individual difference associated with the effectiveness of Contingency Management (CM). It also tested the hypothesis that a dopaminergic drug, levodopa (L-DOPA), would improve the effectiveness of CM, particularly in individuals high in anhedonia. The study was a single-site, randomized, double-blind, parallel group, 12-week trial comparing L-DOPA with placebo, with both medication groups receiving voucher-based CM targeting cocaine-negative urines. Participants were N=85 treatment-seeking adults with CUD. Anhedonia was measured at baseline using a validated self-report measure and a progressive ratio behavioral measure. Treatment Effectiveness Score (TES) was defined as the total number of cocaine-negative urines submitted. Analyses based on Frequentist general linear models were not significant, but Bayesian analyses indicated a high probability (92.6%) that self-reported anhedonia was associated with poor treatment outcomes (lower TES). L-DOPA did not significantly improve outcomes, nor was the effect of L-DOPA moderated by anhedonia. While the study failed to replicate positive findings from previous studies of L-DOPA in combination with CM, it does provide preliminary evidence that anhedonia may be a modifiable individual difference associated with poorer CM outcomes.

Treating tobacco use disorder in pregnant women in medication-assisted treatment for an opioid use disorder: a systematic review

Smoking is associated with adverse effects on pregnancy and fetal development, yet 88-95% of pregnant women in medication-assisted treatment for an opioid use disorder smoke cigarettes. This review summarizes existing knowledge about smoking cessation treatments for pregnant women on buprenorphine or methadone, the two forms of medication-assisted treatment for opioid use disorder indicated for prenatal use. We performed a systematic review of the literature using indexed terms and key words to capture the concepts of smoking, pregnancy, and opioid substitution and found that only three studies met search criteria. Contingency management, an incentive based treatment, was the most promising intervention: 31% of participants achieved abstinence within the 12-week study period, compared to 0% in a non-contingent behavior incentive group and a group receiving usual care. Two studies of brief behavioral interventions resulted in reductions in smoking but not cessation. Given the growing number of pregnant women in medication-assisted treatment for an opioid use disorder and the negative consequences of smoking on pregnancy, further research is needed to develop and test effective cessation strategies for this group.

Spontaneous reductions in smoking during double-blind buprenorphine detoxification

OBJECTIVE

Evidence suggests a positive association between administration of psychoactive drugs and rates of cigarette smoking. Prevalence of smoking among opioid-dependent individuals, for example, is four times greater than the general population. We recently completed a randomized double-blind trial evaluating outpatient buprenorphine taper for prescription opioid (PO) abusers, which provided a unique opportunity to examine naturalistic changes in smoking among participants who detoxified without resumption of illicit opioid use.

METHOD

Participants received no smoking-cessation services and were not encouraged to alter their smoking in any way. A subset of 10 opioid-dependent smokers, who were randomized to receive the same 4-week buprenorphine taper and successfully completed detoxification, were included in the present study. They provided staff-observed urine specimens thrice-weekly throughout the 12-week trial. Specimens were analyzed on-site via enzyme-multiplied immunoassay for urinary cotinine, a metabolite of nicotine that provides a sensitive biochemical measure of smoking status.

RESULTS

Mean cotinine levels were significantly different across study phases, with significantly lower cotinine levels during taper (1317.5 ng/ml) and post-taper (1015.8 ng/ml) vs. intake (1648.5 ng/ml) phases (p''s<.05). Overall, mean cotinine levels decreased by 38% between intake and end-of-study, reflecting a reduction of approximately eight cigarettes per day.

CONCLUSIONS

These data provide additional evidence that opioids influence smoking and extend prior findings to include primary PO abusers, rigorous double-blind opioid dosing conditions and urinary cotinine. These results also suggest that, while likely insufficient for complete cessation, patients who successfully taper from opioids may also experience concurrent reductions in smoking and thus may be ideal candidates for smoking cessation services.

Stimulant treatment of ADHD and cigarette smoking: a meta-analysis

BACKGROUND AND OBJECTIVE

Individuals with attention-deficit/hyperactivity disorder (ADHD) have a significantly higher risk of cigarette smoking. The nature of the relationship between smoking and psychostimulant medications commonly used to treat ADHD is controversial. Our objective was to examine the relationship between stimulant treatment of ADHD and cigarette smoking by using meta-analysis, and to identify study and sample characteristics that moderate this relationship.

METHODS

Literature searches on PubMed and PsycInfo databases identified published studies for inclusion. Included studies compared cigarette smoking outcomes for stimulant-treated and untreated ADHD individuals. Seventeen studies met inclusion criteria, and 14 (total n = 2360) contained sufficient statistical information for inclusion in the meta-analysis. Two authors extracted odds ratios or frequencies of smokers in the treatment or nontreatment groups, and coded study characteristics including sample source, percentage of male participants, follow-up length, treatment consistency, type of smoking measure, prospective study, and controlling for comorbidities.

RESULTS

Meta-analysis revealed a significant association between stimulant treatment and lower smoking rates. Meta-regression indicated that effect sizes were larger for studies that used clinical samples, included more women, measured smoking in adolescence rather than adulthood, conceptualized stimulant treatment as consistent over time, and accounted for comorbid conduct disorder.

CONCLUSIONS

Nearly all studies were naturalistic, precluding causal inferences. Available data were insufficient to examine additional influences of patient demographics, treatment effectiveness, or other comorbidities. Consistent stimulant treatment of ADHD may reduce smoking risk; the effect was larger in samples with more severe psychopathology. Implications for further research, treatment of ADHD, and smoking prevention are discussed.

Methylphenidate does not influence smoking-reinforced responding or attentional performance in adult smokers with and without attention deficit hyperactivity disorder (ADHD)

Individuals with Attention Deficit Hyperactivity Disorder (ADHD) smoke cigarettes at rates higher than the general population and questions have been raised about how stimulant drugs-the frontline pharmacological treatment for ADHD-influence smoking risk and behavior in those with ADHD. In the present study adult regular smokers with (n = 16) and without (n = 17) ADHD participated in 3 experimental sessions in which they completed a Progressive Ratio (PR) task to measure the relative reinforcing effects of cigarette smoking and money after oral administration of placebo and 2 active doses of methylphenidate (10 mg and 40 mg). We also measured attention and inhibitory control via a Continuous Performance Test (CPT). Methylphenidate had no effect on smoking-reinforced responding, attention, or inhibitory control in either group. Attention and inhibitory control were associated with smoking-reinforced responding, but unsystematically and only in the non-ADHD group. Several design features, such as the value of the monetary response option, the PR schedule, and the potential effects of smoking on attention and inhibitory control, could have contributed to the negative findings and are discussed as such. Although inconsistent with some previous human laboratory studies of stimulant drugs and smoking, results are consistent with recent trials of stimulant drugs as adjuncts for smoking cessation in adult smokers with ADHD. In general, methylphenidate at mild and moderate doses did not influence the relative reinforcing effects of cigarette smoking in adults with and without ADHD.

Treating nicotine dependence by targeting attention-deficit/ hyperactivity disorder (ADHD) with OROS methylphenidate: the role of baseline ADHD severity and treatment response

OBJECTIVE

To determine whether treatment of attention-deficit/hyperactivity disorder (ADHD) with osmotic-release oral system (OROS) methylphenidate promotes abstinence from smoking among smokers with ADHD who have greater severity of ADHD symptoms at baseline or greater improvement in ADHD during treatment.

METHOD

This is a secondary analysis of data from a randomized, double-blind, 11-week trial conducted between December 2005 and January 2008 at 6 clinical sites; the original trial was sponsored by the National Drug Abuse Clinical Trials Network. Adult cigarette smokers (aged 18-55 years) who met DSM-IV criteria for ADHD were randomly assigned to OROS methylphenidate (72 mg/d) (n = 127) or matching placebo (n = 128). All participants received nicotine patches (21 mg/d) and weekly individual smoking cessation counseling. Logistic regression was used to model prolonged abstinence from smoking (ascertained by self-report and breath carbon monoxide testing) as a function of treatment, baseline ADHD Rating Scale-IV (ADHD-RS) score, change in ADHD-RS score during treatment, and their interactions.

RESULTS

Treatment interacted with both ADHD-RS score at baseline (P = .01) and change in ADHD-RS score during treatment (P = .008). Among patients with higher ADHD-RS scores (> 36) at baseline and the most improvement in ADHD during treatment (ADHD-RS change score ≥ 24), 70.0% of those who took OROS methylphenidate achieved abstinence from smoking compared to 36.8% of those who took placebo (P = .02). In contrast, among patients with the lowest ADHD-RS baseline scores (≤ 30), 30.3% of those who took OROS methylphenidate achieved abstinence from smoking compared to 60.7% of those who took placebo (P = .02).

CONCLUSIONS

OROS methylphenidate, in combination with nicotine patch, may be an effective treatment for nicotine dependence among smokers with more severe ADHD and more robust response of ADHD symptoms to medication. OROS methylphenidate may be counterproductive among smokers with lower severity of ADHD.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00253747.

Vulnerability to smokeless tobacco use among those dependent on alcohol or illicit drugs

INTRODUCTION

Individuals dependent on alcohol or illicit drugs are vulnerable to cigarette smoking and related adverse health outcomes. Less research has been conducted regarding whether these same groups are vulnerable to smokeless tobacco (ST) use. The goal of this study is to examine vulnerability to ST use among individuals with other drug dependence.

METHODS

Utilizing the most recent (2011) National Survey on Drug Use and Health (NDSUH), we determined odds ratios (ORs) for current cigarette smoking and ST use among those with current alcohol, cocaine, heroin, and marijuana dependence, adjusting for relevant sociodemographic characteristics. Vulnerability to cigarette smoking was assessed to confirm that alcohol and illicit drug dependence were associated with increased smoking in these data sets, as shown in prior studies. Identical analyses were completed in the 2009 and 2010 NSDUH to assess generality.

RESULTS

Odds for current cigarette smoking were increased for each category of dependence (p < .0005): alcohol (OR with 99% CI = 3.30 [2.58, 4.21]), cocaine (OR = 4.50 [1.53, 13.20]), heroin (OR = 7.84 [1.92, 32.03]), and marijuana (OR = 3.55 [2.59, 4.88]). Odds for current ST use were also increased among those with alcohol dependence (OR = 1.56 [1.06, 2.30], p = .003) but not illicit drug dependence. Generality of the findings was confirmed in the 2009 and 2010 NSDUH.

CONCLUSIONS

Consistent with earlier reports, alcohol and illicit drug dependence are associated with robust increases in risk for cigarette smoking. In the case of alcohol dependence, but not illicit drug dependence, this vulnerability also extends to ST use.

An Exploration of Responses to Drug Conditioned Stimuli during Treatment for Substance Dependence

Although it is well established that drug conditioned stimuli produce a variety of conditioned responses, it is not known whether such stimuli can also reinforce an arbitrary operant response and thus serve as conditioned reinforcers. Volunteers (n = 39) recruited from a residential treatment center for substance dependence were tested on a task in which presses on computer keys activated images of drugs/drug paraphernalia on a progressive ratio schedule of reinforcement. They also completed a personalized craving questionnaire and a personalized Implicit Association Test. A significant bias in responding was found for images of preferred drugs/route of drug administration. Craving, however, was low and the images generated negative evaluative reactions. Two additional studies were performed to ascertain the generalizability of the effects to a different population of drug-using individuals (i.e., students who drink) and to incentive stimuli of a different nature (i.e., sexual). The additional studies partially replicated and extended the central findings of the main study. Therefore, although these data should be considered preliminary in light of small group sizes, it is concluded that cue specificity and availability of the unconditioned stimuli (drugs and sex) plays a role in modulating responding maintained by conditioned reinforcers.

The influence of smoking cigarettes on the high and desire for cocaine among active cocaine users

The primary aim was to evaluate whether nicotine use alters the high or desire for cocaine among active cocaine users who concurrently smoke cigarettes. Participants answered the Fagerstrom Test for Nicotine Dependence (FTND), Nicotine-Stimulant Interaction Questionnaire (NSIQ), and Multiple Drug Use Questionnaire (MDUQ). These questionnaires employ subject recall of participants' drug use habits. The participants that smoked (N=163/188) were primarily African American males who were 45.0±0.5 (mean±S.E.M.) years of age, and used cocaine for 17.9±0.6 years and 19.8±0.6 days out of the last 30. These individuals smoked 14.0±0.8 cigarettes/day (CPD), scored 4.6±0.2 (on a scale of 0-10) on the FTND, and smoked cigarettes for 23.5±0.7 years. Two questions from the MDUQ, which evaluates the interaction between cocaine and nicotine, (-5: reduces effect, 0: no change, +5: increases effect) included "Does nicotine affect the high that you experience from cocaine?" and "Does nicotine affect your desire for cocaine?", and the scores were 1.3±0.2 and 0.8±0.2, respectively. The NSIQ also evaluated interactive effects of nicotine and cocaine, on a scale of 0 to 100 (0: not at all, 100: most ever). Smokers responded most strongly that using cocaine increased both the urge to smoke and cigarette craving. Additional analyses were performed by separating participants into HighCPD vs. LowCPD groups via median split. The HighCPD group smoked 22.7±1.1 CPD while the LowCPD group smoked 6.4±0.3 CPD [F(1,161)=228.4, p<0.0001], and the HighCPD group had a mean FTND score twice that of the LowCPD group. Significant differences emerged between the two groups on multiple items of the NSIQ, but not the MDUQ. The subjective ratings of high and desire for cocaine, and several subjective effects produced by cocaine, were modestly altered by cigarette smoking. Taken together, these data suggest that cigarette smoking may augment the craving and high produced by cocaine.

Effects of smoking abstinence on smoking-reinforced responding, withdrawal, and cognition in adults with and without attention deficit hyperactivity disorder

RATIONALE

Individuals with attention deficit hyperactivity disorder (ADHD) have a more difficult time quitting smoking compared to their non-ADHD peers. Little is known about the underlying behavioral mechanisms associated with this increased risk.

OBJECTIVES

This study aims to assess the effects of 24-h smoking abstinence in adult smokers with and without ADHD on the following outcomes: smoking-reinforced responding, withdrawal, and cognitive function.

METHODS

Thirty-three (n = 16 with ADHD, 17 without ADHD) adult smokers (more than or equal to ten cigarettes/day) were enrolled. Each participant completed two experimental sessions: one following smoking as usual and one following biochemically verified 24-h smoking abstinence. Smoking-reinforced responding measured via a progressive ratio task, smoking withdrawal measured via questionnaire, and cognition measured via a continuous performance test (CPT) were assessed at each session.

RESULTS

Smoking abstinence robustly increased responding for cigarette puffs in both groups, and ADHD smokers responded more for puffs regardless of condition. Males in both groups worked more for cigarette puffs and made more commission errors on the CPT than females, regardless of condition. Smoking abstinence also increased ratings of withdrawal symptoms in both groups and smokers with ADHD, regardless of condition, reported greater symptoms of arousal, habit withdrawal, and somatic complaints. Across groups, smoking abstinence decreased inhibitory control and increased reaction time variability on the CPT. Abstinence-induced changes in inhibitory control and negative affect significantly predicted smoking-reinforced responding across groups.

CONCLUSIONS

Smokers with ADHD reported higher levels of withdrawal symptoms and worked more for cigarette puffs, regardless of condition, which could help explain higher levels of nicotine dependence and poorer cessation outcomes in this population. Abstinence-induced changes in smoking-reinforced responding are associated with changes in inhibitory control and negative affect regardless of ADHD status, a finding that may lead to novel prevention and treatment programs.

Methylphenidate increases cigarette smoking in participants with ADHD

RATIONALE

Methylphenidate (Ritalin®) is commonly prescribed for behavioral problems associated with attention deficit/hyperactivity disorder (ADHD). The results of previous studies suggest that methylphenidate increases cigarette smoking in participants without psychiatric diagnoses. Whether methylphenidate increases cigarette smoking in participants diagnosed with ADHD is unknown.

OBJECTIVE

In this within-subjects, repeated measures experiment, the acute effects of a range of doses of methylphenidate (10, 20, and 40 mg) and placebo were assessed in nine cigarette smokers who were not attempting to quit and met diagnostic criteria for ADHD but no other Axis I psychiatric disorders other than nicotine dependence.

METHODS

Each dose of methylphenidate was tested once while placebo was tested twice. One hour after ingesting drug, participants were allowed to smoke ad libitum for 4 h. Measures of smoking included total cigarettes smoked, total puffs, and carbon monoxide levels. Snacks and decaffeinated drinks were available ad libitum; caloric intake during the 4-h smoking session was calculated.

RESULTS

Methylphenidate increased the total number of cigarettes smoked, total number of puffs, and carbon monoxide levels. Methylphenidate decreased the number of food items consumed and caloric intake.

CONCLUSIONS

The results of this experiment suggest that acutely administered methylphenidate increases cigarette smoking in participants with ADHD, which is concordant with findings from previous studies that tested healthy young adults. These data indicate that clinicians may need to consider non-stimulant options or counsel their patients before starting methylphenidate when managing ADHD-diagnosed individuals who smoke.

Caffeine choice prospectively predicts positive subjective effects of caffeine and d-amphetamine

BACKGROUND

Individuals vary in their subjective and behavioral response to psychomotor stimulants and these differences may be associated with the likelihood of developing problematic use of these drugs. The present study sought to determine whether individual differences in caffeine choice prospectively predict subjective response to acute doses of caffeine and d-amphetamine.

METHODS

In Phase 1, Choosers and Nonchoosers of caffeine were identified using 10 independent choice trials in which subjects repeatedly chose between caffeine (200mg/70 kg) and placebo. Choosers were defined as those who chose caffeine over placebo on ≥7 of the 10 trials; Nonchoosers were those who chose placebo on ≥7 trials. In Phase 2, Choosers and Nonchoosers were compared in their subjective response to caffeine (100, 200, 400mg/70 kg) and d-amphetamine (5, 10, 20 mg/70 kg).

RESULTS

Of the 22 participants completing the study, 11 met criteria for being a caffeine Chooser and 8 were Nonchoosers. In Phase 1, Choosers reported higher ratings of positive (i.e., pleasant) and lower ratings of negative (i.e., unpleasant) effects of caffeine during the sampling sessions. In Phase 2, caffeine Choosers reported more positive subjective effects and fewer negative effects of caffeine and d-amphetamine, particularly at the highest doses examined.

CONCLUSIONS

Individual differences in caffeine reinforcement predicted subsequent subjective response to both d-amphetamine and caffeine. This observation may have clinical utility for identifying individuals who are vulnerable to the reinforcing effects of abused psychomotor stimulants.

Methylphenidate increases choice of cigarettes over money

INTRODUCTION

Stimulants increase cigarette smoking in the naturalistic environment and laboratory. The effects of methylphenidate on a 9-trial, discrete cigarette versus money ($0.25) choice task were tested to elucidate the mechanisms underlying stimulant-induced increases in smoking.

METHODS

Eleven participants who reported smoking 10-20 cigarettes/day completed the study. Four doses of methylphenidate (0, 10, 20, and 40 mg) were administered across 5 experimental sessions, with placebo administered twice. One hour following medication administration and at 30-min intervals thereafter, participants chose between smoking a cigarette and receiving US$0.25. The primary behavioral outcome measure was number of cigarette choices.

RESULTS

Methylphenidate increased the number of cigarette choices over money. Puffs per session and carbon monoxide levels increased significantly and caloric intake decreased significantly following methylphenidate administration relative to placebo.

CONCLUSIONS

The results of this study suggest that methylphenidate increases the relative reinforcing efficacy of cigarette smoking. Stimulant use may thus be an important consideration for individuals attempting to quit smoking.

The sensitizing effect of acute nicotine on amphetamine-stimulated behavior and dopamine efflux requires activation of β2 subunit-containing nicotinic acetylcholine receptors and glutamate N-methyl-D-aspartate receptors

Nicotine has been demonstrated to enhance the subsequent use of illicit drugs in animals and humans. We previously demonstrated in female, Holtzman rats that one low dose of nicotine will potentiate locomotor activity and dopamine (DA) efflux in response to a subsequent low dose of d-amphetamine (AMPH) given 1-4 h later. In the present study, we show this also occurs in male rats and characterize the receptors required for the rapid sensitizing effect of nicotine on AMPH-stimulated locomotor behavior and AMPH-induced DA efflux. Pretreatment of male, Holtzman rats with a low dose (0.1 mg/kg, i.p.) of nicotine 2-4 h before a challenge with AMPH (0.32 mg/kg, i.p.) enhanced locomotor behavior as compared to saline pretreatment. Dihydro-β-erythroidine (DHβE), a relatively selective antagonist at β2 subunit-containing (β2∗) nicotinic acetylcholine receptors (nAChR), but not methyllycaconitine (MLA), a relatively selective antagonist at α7 nAChRs, blocked the sensitizing effect of nicotine on AMPH-stimulated locomotor activity. Pretreatment with varenicline, a partial agonist selective for β2∗ nAChRs, blocked the sensitizing effect of nicotine on AMPH-stimulated locomotor behavior. Nicotine pretreatment sensitized AMPH-induced DA overflow in slices from ventral (nucleus accumbens, NAc), but not dorsal striatum as compared to saline-pretreated rats. Nicotine sensitization of the DA overflow was blocked by DHβE. Pretreatment with the glutamate N-methyl-D-aspartate (NMDA) receptor antagonist (+)-MK-801 (0.1 mg/kg, s.c.) 30 min before nicotine blocked sensitization of both locomotion and DA overflow in response to AMPH challenge. These results demonstrate that activation of the β2∗ nAChRs and NMDA receptors are required for the rapid sensitizing effect of nicotine on AMPH actions. This article is part of a Special Issue entitled 'Trends in neuropharmacology: in memory of Erminio Costa'.

Reinforcing effects of stimulants in humans: sensitivity of progressive-ratio schedules

Drug self-administration methodologies have been developed for use in humans to model naturalistic stimulant drug-taking behaviors. These methodologies use a number of schedules of reinforcement, including progressive-ratio schedules. As the name implies, in a progressive-ratio schedule, the response requirement for each subsequent delivery of drug increases, and the primary outcome variable is often the break point (i.e., the last ratio completed to receive a drug delivery). These schedules have been used in a number of human laboratory studies evaluating the reinforcing effects of stimulants. The results of these studies have demonstrated that progressive-ratio schedules are sensitive to manipulation of a pharmacological variable, dose, and to nonpharmacological variables contributing to stimulant drug effects. In addition, findings with progressive-ratio schedules are largely concordant with clinical findings, suggesting that drug self-administration under these schedules has predictive validity in terms of drug abuse and dependence. Future research is necessary, however, to understand better how pharmacological factors like route of administration, onset of effects, and pretreatment influence the reinforcing effects of stimulants under progressive-ratio schedules.

Nicotine and amphetamine acutely cross-potentiate their behavioral and neurochemical responses in female Holtzman rats

RATIONALE

Psychostimulants are often used in close temporal proximity to nicotine and have been reported to enhance acutely nicotine's desirability in humans.

OBJECTIVE

To investigate the acute associations between amphetamine and nicotine, we examined the potentiative interactions between clinically relevant, low doses of these drugs on locomotor activity, and dopamine overflow in the rat.

MATERIALS AND METHODS

Locomotor activity was measured by telemetry in the home cage environment, and dopamine overflow was evaluated in striatal slice preparations from female Holtzman rats.

RESULTS

When administered simultaneously, nicotine and amphetamine produced a predominantly additive effect on locomotor behavior. However amphetamine, when given 2-4 h before nicotine, strongly potentiated nicotine-induced locomotor activity. Correspondingly, nicotine given 1-4 h before amphetamine robustly enhanced amphetamine-stimulated locomotor activity even when the effects of the nicotine pretreatment dissipated. Acute nicotine pretreatment similarly potentiated the effects of dopamine transporter ligands, cocaine, nomifensine, and methamphetamine but not a direct dopamine receptor agonist. Consistent with the behavioral studies, in vivo nicotine pretreatment exaggerated amphetamine-induced dopamine efflux from rat striatal slices. Likewise, in vivo pretreatment of rats with amphetamine potentiated nicotine-induced dopamine efflux from striatal slices. Direct pretreatment of striatal tissue by nicotine also potentiated subsequent amphetamine-stimulated dopamine overflow, further suggesting that the nicotine-amphetamine interaction occurs at the level of the dopamine terminal.

CONCLUSION

Overall, the present data demonstrate that acute interactions of nicotine and other psychomotor stimulants produce potentiative effects and that these transient interactions may play a role in the frequent co-use and abuse of nicotine and other stimulants.

Methylphenidate enhances the abuse-related behavioral effects of nicotine in rats: intravenous self-administration, drug discrimination, and locomotor cross-sensitization

Stimulant drugs, including D-amphetamine, cocaine, and methylphenidate, increase cigarette smoking in controlled human laboratory experiments. Although the mechanism(s) underlying this effect are unknown, it is possible that stimulants may enhance directly the abuse-related effects of nicotine. In the present study, we characterized the behavioral pharmacological interactions between methylphenidate and nicotine in the intravenous self-administration, drug discrimination, and locomotor cross-sensitization procedures. Adult male Sprague-Dawley rats were trained to respond for intravenous nicotine (0.01 or 0.03 mg/kg/infusion) or sucrose, and the acute effects of methylphenidate (1.25-10 mg/kg) were determined; in addition, separate groups of rats were treated with methylphenidate (2.5 mg/kg) or saline before 12 consecutive nicotine (0.03 mg/kg/infusion) self-administration sessions. Next, the discriminative stimulus effects of nicotine (0.03-0.3 mg/kg) and methylphenidate (1.25-10 mg/kg), alone and in combination with a low nicotine dose (0.056 mg/kg), were tested in nicotine-trained rats. Finally, the locomotor effect of repeated methylphenidate (2.5 mg/kg) was tested in rats previously treated with nicotine (0.2-0.8 mg/kg). Results indicated that acute methylphenidate increased the rate of nicotine self-administration at doses that reduced sucrose-maintained responding; furthermore, tolerance to this effect was not apparent following repeated methylphenidate. Methylphenidate, while not substituting for nicotine alone, dose-dependently enhanced the discriminative stimulus effect of a low nicotine dose. In addition, repeated nicotine exposure promoted the development of locomotor sensitization to methylphenidate. Taken together with recent clinical findings, these results suggest that methylphenidate may enhance the abuse-related behavioral effects of nicotine, perhaps increasing vulnerability to tobacco dependence.

A pharmacological analysis of stimulant-induced increases in smoking

RATIONALE

Stimulants increase tobacco smoking in healthy adults under controlled laboratory conditions. The mechanisms that mediate stimulant-induced increases in smoking are not known.

OBJECTIVE

The purpose of the present experiment was to characterize the pharmacological specificity of stimulant-induced increases in smoking. We tested the effects of methylphenidate and atomoxetine on smoking behavior. Atomoxetine is a norepinephrine transport inhibitor that does not increase dopamine levels in the nucleus accumbens or striatum. If stimulant-induced increases in smoking result from an additive or synergistic effect of these drugs and nicotine on dopamine levels in the nucleus accumbens or striatum, methylphenidate but not atomoxetine should increase smoking.

MATERIALS AND METHODS

Doses of methylphenidate (10, 20, and 40 mg) and atomoxetine (20, 40, and 80 mg) were tested once while placebo was tested twice in 12 cigarette smokers. One hour after ingesting drug, participants smoked ad libitum for 4 h. Measures of smoking included total cigarettes, total puffs, and carbon monoxide levels. Snacks and decaffeinated drinks were available ad libitum, and food intake was calculated.

RESULTS

Methylphenidate but not atomoxetine dose-dependently increased the number of cigarettes, puffs, and carbon monoxide levels. Methylphenidate and atomoxetine decreased food intake.

CONCLUSIONS

The results of this experiment are consistent with the notion that stimulant-induced increases in smoking may result from an additive or synergistic effect of these drugs and nicotine on dopamine levels in the nucleus accumbens or striatum. Additional research is needed to more fully understand the pharmacological mechanisms that mediate the relationship between stimulant use and smoking.

Investigating the pharmacological and nonpharmacological factors that modulate drug reinforcement

Drug use is driven by principles of reinforcement and is sensitive to influences in the environmental context in which it occurs. Although a wide range of factors has been shown to directly influence the reinforcing effects of commonly abused drugs, 2 general types include pharmacological and nonpharmacological factors. Both can assert a powerful impact on a drug's reinforcing effects and, therefore, the degree to which a particular drug comes to be used and abused. This invited review seeks to briefly describe some of the current psychopharmacology research on the interactions between these factors and drug abuse. Several pharmacological influences on drug use will be discussed, including the interactions between psychomotor stimulants and recent advances in the development of pharmacotherapies for opioid abuse. With regard to nonpharmacological factors, there is a large body of research demonstrating that nondrug reinforcers can exert a powerful influence on the reinforcing effects of commonly abused drugs. More specifically, identifying alternative nondrug sources of reinforcement can, if made available contingent on drug abstinence, produce robust decreases in drug self-administration. Presented here is a very brief review of some recent scientific efforts to develop and extend behavioral interventions targeting drug use across a wide range of clinical populations. In summary, understanding the interactions among the variables present in the context of drug use is critical to understanding risk factors for substance use disorders as well as developing efficacious treatments for drug dependence.

Methylphenidate increases cigarette smoking

RATIONALE

Methylphenidate (Ritalin) and d-amphetamine (Dexedrine), stimulants commonly prescribed for behavioral problems associated with attention deficit hyperactivity disorder (ADHD), produce a similar constellation of behavioral effects. The results of previous studies suggest that d-amphetamine increases rates of smoking and the reinforcing effects of smoking. The effects of methylphenidate on smoking have not been assessed although it is the most commonly prescribed pharmacotherapy for ADHD and individuals with ADHD are at increased risk for smoking.

OBJECTIVE

In this experiment the acute effects of a range of doses of methylphenidate (5, 10, 20, and 40 mg) and placebo were assessed in ten cigarette smokers who were not attempting to quit and were without ADHD or other Axis I psychiatric disorders.

METHODS

Each dose of methylphenidate was tested once, whereas placebo was tested twice. One hour after ingesting drug, participants were allowed to smoke ad libitum for 4 h. Measures of smoking included total cigarettes smoked, total puffs, latency to the first cigarette, and carbon monoxide levels. Snacks and decaffeinated drinks were available ad libitum, and caloric intake during the 4-h smoking session was calculated.

RESULTS

Methylphenidate dose dependently increased the total number of cigarettes smoked, number of puffs, and carbon monoxide levels. As expected, methylphenidate dose dependently decreased the number of food items consumed and caloric intake.

CONCLUSIONS

The results of this experiment suggest that methylphenidate, like d-amphetamine, increases rates of cigarette smoking.