Evaluating the effect of switching to non-menthol cigarettes among current menthol smokers: an empirical study of a potential ban of characterising menthol flavour in cigarettes

Introduction

Menthol cigarette use remains a serious public health problem, prompting the consideration of tobacco regulatory efforts to ban menthol cigarettes. The current study uses a novel empirical design to model the potential effects of a ban of menthol cigarettes on smoking behaviour among current menthol smokers.

Methods

29 non-treatment-seeking adults who smoked menthol cigarettes were recruited in Connecticut in 2017–2018 (n=15 female; n=17 Black, n=10 White, n=5 Hispanic). Repeated-measures analyses examined within-person changes in smoking behaviour when participants were switched from smoking their usual brand menthol cigarettes to a matched-brand non-menthol cigarette for 2 weeks to model a potential ban of menthol cigarettes.

Results

Participants smoked significantly fewer non-menthol (vs menthol) cigarettes per day (mean decrease=2.2 cigarettes, SD=3.2, p<0.001), confirmed by significant reductions in urine cotinine levels (p=0.013). After switching to non-menthol cigarettes, participants had significantly lower nicotine dependence scores (reduced by >18%, p<0.001) and greater increases in quitting motivation and confidence (rated 1–10) (motivation: mean increase=2.1, SD=2.8, p<0.001; confidence: mean increase=1.3, SD=3.3, p=0.04). Exploratory analyses indicated significant interactions by race (p=0.004); Black smokers had greater reductions in cigarettes per day (mean decrease=3.5 cigarettes, SD=2.8) versus non-Black smokers (mean decrease=0.2, SD=2.6).

Conclusions

Banning menthol as a characterising flavour in cigarettes may decrease smoking and reduce the addictive potential of cigarettes among current smokers. Results provide additional support for tobacco regulatory policies banning menthol flavour in an effort to improve public health.

Trial registration

NCT03075839.

Use of Electronic Cigarettes Leads to Significant Beta2-Nicotinic Acetylcholine Receptor Occupancy: Evidence From a PET Imaging Study

Background

Electronic cigarettes (ECs) can influence nicotine addiction by delivering aerosolized nicotine. We investigated if nicotine from ECs is delivered to the brain β2*-nicotinic acetylcholine receptors (β2*-nAChR) and how this relates to the behavioral effects and nicotine delivery from cigarettes.

Methods

Seven nicotine users participated in positron emission tomography (PET) studies with (-)-[18F]Flubatine before and after nicotine challenge with 0, 8, and 36 mg/ml nicotine in a 3.3 Volt, 1.5 Ohm EC or a standard tobacco cigarette. Craving was evaluated before and after product use.

Results

Average β2*-nAChR occupancy was higher after 36 mg/ml EC challenge compared to 8 mg/ml EC at trend level. Average β2*-nAChR occupancy after tobacco cigarette smoking was 68 ± 18% and was not different compared with 8 mg/ml (64 ± 17%,) or 36 mg/ml (84 ± 3%) nicotine in EC users. Area under the curve (AUC) of blood nicotine level was higher in the cigarette smoking group compared with the 8mg/ml group (p = 0.03), but similar compared with the 36 mg/ml EC (p = 0.29). Drug craving was reduced after use of the tobacco cigarette, 8 mg/ml EC, and 36 mg/ml EC.

Conclusions

In this novel investigation of EC effects at β2*-nAChRs, we show that average β2*-nAChR occupancy was higher after 36 mg/ml EC challenge compared with 8 mg/ml EC. Receptor occupancy and arterial blood nicotine levels after cigarette smoking were similar to 36 mg/ml EC use under controlled conditions. These findings suggest that the ECs studied here have abuse liability and may provide an adequate alternative nicotine delivery system for cigarette smokers.

Implications

This is the first study to directly determine the neurologic effects of electronic cigarettes on human brain beta-2 nicotinic acetylcholine receptors using PET neuroimaging with (-)-[18F]Flubatine, a novel radiotracer. Our findings suggest that the e-cigarettes studied here have abuse liability and may provide an adequate alternative nicotine delivery system for cigarette smokers.

Effect of Varenicline Combined With Medical Management on Alcohol Use Disorder With Comorbid Cigarette Smoking: A Randomized Clinical Trial

IMPORTANCE

Individuals with alcohol use disorder have high rates of cigarette smoking. Varenicline tartrate, an approved treatment for smoking cessation, may reduce both drinking and smoking.

OBJECTIVES

To test the efficacy of varenicline with medical management for patients with alcohol use disorder and comorbid smoking seeking alcohol treatment, and to evaluate the secondary effects on smoking abstinence.

DESIGN, SETTING, AND PARTICIPANTS

This phase 2, randomized, double-blind, parallel group, placebo-controlled trial was conducted at 2 outpatient clinics from September 19, 2012, to August 31, 2015. Eligible participants met alcohol-dependence criteria and reported heavy drinking (≥5 drinks for men and ≥4 drinks for women) 2 or more times per week and smoking 2 or more times per week; 131 participants were randomized to either varenicline or placebo stratified by sex and site. All analyses were of the intention-to-treat type. Data analysis was conducted from February 5, 2016, to September 29, 2017.

INTERVENTIONS

Varenicline tartrate, 1 mg twice daily, and matching placebo pills for 16 weeks. Medical management emphasized medication adherence for 4 weeks followed by support for changing drinking.

MAIN OUTCOMES AND MEASURES

Percentage of heavy drinking days (PHDD) weeks 9 to 16, no heavy drinking days (NHDD) weeks 9 to 16, and prolonged smoking abstinence weeks 13 to 16.

RESULTS

Of 131 participants, 39 (29.8%) were women and 92 (70.2%) were men, the mean (SD) age was 42.7 (11.7) years, and the race/ethnicity self-identified by most respondents was black (69 [52.7%]). Sixty-four participants were randomized to receive varenicline, and 67 to receive placebo. Mean change in PHDD between varenicline and placebo across sex and site was not significantly different. However, a significant treatment by sex by time interaction for PHDD (F1,106 = 4.66; P = .03) revealed that varenicline compared with placebo resulted in a larger decrease in log-transformed PHDD in men (least square [LS] mean difference in change from baseline, 0.54; 95% CI, -0.09 to 1.18; P = .09; Cohen d = 0.45) but a smaller decrease in women (LS mean difference, -0.69; 95% CI, -1.63 to 0.25; P = .15; Cohen d = -0.53). Thirteen of 45 men (29%) had NHDD taking varenicline compared with 3 of 47 men (6%) taking placebo (Cohen h = 0.64; 95% CI, 0.22-1.03), whereas 1 of 19 women (5%) had NHDD compared with 5 of 20 women (25%) taking placebo (Cohen h = -0.60; 95% CI, -1.21 to 0.04). Taking varenicline, 8 of 64 participants (13%) achieved prolonged smoking abstinence; no one (0 of 67) quit smoking taking placebo (P = .003; Cohen h = 0.72; 95% CI, 0.38-1.07).

CONCLUSIONS AND RELEVANCE

Varenicline with medical management resulted in decreased heavy drinking among men and increased smoking abstinence in the overall sample. Varenicline could be considered to promote improvements in men with these dual behavioral health risks.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01553136.

Studying the interactive effects of menthol and nicotine among youth: An examination using e-cigarettes

BACKGROUND

Tobacco products containing menthol are widely used by youth. We used e-cigarettes to conduct an experimental evaluation of the independent and interactive effects of menthol and nicotine among youth.

PROCEDURES

Pilot chemosensory experiments with fourteen e-cigarette users identified low (barely perceptible, 0.5%) and high (similar to commercial e-liquid, 3.5%) menthol concentrations. Sixty e-cigarette users were randomized to a nicotine concentration (0mg/ml, 6mg/ml, 12mg/ml) and participated in 3 laboratory sessions. During each session, they received their assigned nicotine concentration, along with one of three menthol concentrations in random counterbalanced order across sessions (0, 0.5%, 3.5%), and participated in three fixed-dose, and an ad-lib, puffing period. Urinary menthol glucuronide and salivary nicotine levels validated menthol and nicotine exposure. We examined changes in e-cigarette liking/wanting and taste, coolness, stimulant effects, nicotine withdrawal and ad-lib use.

RESULTS

Overall, the high concentration of menthol (3.5%) significantly increased e-cigarette liking/wanting relative to no menthol (p<0.001); there was marginal evidence of nicotine* menthol interactions (p=0.06), with an increase in liking/wanting when 3.5% menthol was combined with 12mg/ml nicotine, but not 6mg/ml nicotine. Importantly, both 0.5% and 3.5% menthol concentrations significantly improved taste and increased coolness. We did not observe nicotine or menthol-related changes in stimulant effects, nicotine withdrawal symptoms or ad-lib use.

CONCLUSIONS

Menthol, even at very low doses, alters the appeal of e-cigarettes among youth. Further, menthol enhances positive rewarding effects of high nicotine-containing e-cigarettes among youth.

Biomarkers of exposure to new and emerging tobacco delivery products

Accurate and reliable measurements of exposure to tobacco products are essential for identifying and confirming patterns of tobacco product use and for assessing their potential biological effects in both human populations and experimental systems. Due to the introduction of new tobacco-derived products and the development of novel ways to modify and use conventional tobacco products, precise and specific assessments of exposure to tobacco are now more important than ever. Biomarkers that were developed and validated to measure exposure to cigarettes are being evaluated to assess their use for measuring exposure to these new products. Here, we review current methods for measuring exposure to new and emerging tobacco products, such as electronic cigarettes, little cigars, water pipes, and cigarillos. Rigorously validated biomarkers specific to these new products have not yet been identified. Here, we discuss the strengths and limitations of current approaches, including whether they provide reliable exposure estimates for new and emerging products. We provide specific guidance for choosing practical and economical biomarkers for different study designs and experimental conditions. Our goal is to help both new and experienced investigators measure exposure to tobacco products accurately and avoid common experimental errors. With the identification of the capacity gaps in biomarker research on new and emerging tobacco products, we hope to provide researchers, policymakers, and funding agencies with a clear action plan for conducting and promoting research on the patterns of use and health effects of these products.

Menthol disrupts nicotine's psychostimulant properties in an age and sex-dependent manner in C57BL/6J mice

Menthol is a commonly used flavorant in tobacco and e-cigarettes, and could contribute to nicotine sensitivity. To understand how menthol could contribute to nicotine intake and addiction, it is important to determine whether specific mechanisms related to sex and age could underlie behavioral changes induced by menthol-laced nicotinic products. Using a validated paradigm of nicotine-dependent locomotor stimulation, adolescent and adult C57BL/6J mice of both sexes were exposed to nicotine, or nicotine laced with menthol, as their sole source of fluid, and psychostimulant effects were evaluated by recording home cage locomotor activity for ten days. Nicotine and cotinine blood levels were measured following exposure. Results show an interaction between treatment, age, and sex on liquid consumption, indicating that mice responded differently to menthol and nicotine based on their age and sex. Adult male mice greatly increased their nicotine intake when given menthol. In female mice of both age groups, menthol did not have this effect. Despite an increase in nicotine intake promoted by menthol, adult male mice showed a significant decrease in locomotion, suggesting that menthol blunted nicotine-induced psychostimulation. This behavioral response to menthol was not detected in adolescent mice of either sex. These data confirm that menthol is more than a flavorant, and can influence both nicotine intake and its psychostimulant effects. These results suggest that age- and sex-dependent mechanisms could underlie menthol's influence on nicotine intake and that studies including adolescent and adult menthol smokers of both sexes are warranted.

Nicotine metabolite ratio (3-hydroxycotinine/cotinine) in plasma and urine by different analytical methods and laboratories: implications for clinical implementation

BACKGROUND

The highly genetically variable enzyme CYP2A6 metabolizes nicotine to cotinine (COT) and COT to trans-3'-hydroxycotinine (3HC). The nicotine metabolite ratio (NMR, 3HC/COT) is commonly used as a biomarker of CYP2A6 enzymatic activity, rate of nicotine metabolism, and total nicotine clearance; NMR is associated with numerous smoking phenotypes, including smoking cessation. Our objective was to investigate the impact of different measurement methods, at different sites, on plasma and urinary NMR measures from ad libitum smokers.

METHODS

Plasma (n = 35) and urine (n = 35) samples were sent to eight different laboratories, which used similar and different methods of COT and 3HC measurements to derive the NMR. We used Bland-Altman analysis to assess agreement, and Pearson correlations to evaluate associations, between NMR measured by different methods.

RESULTS

Measures of plasma NMR were in strong agreement between methods according to Bland-Altman analysis (ratios, 0.82-1.16) and were highly correlated (all Pearson r > 0.96, P < 0.0001). Measures of urinary NMR were in relatively weaker agreement (ratios 0.62-1.71) and less strongly correlated (Pearson r values of 0.66-0.98, P < 0.0001) between different methods. Plasma and urinary COT and 3HC concentrations, while weaker than NMR, also showed good agreement in plasma, which was better than that in urine, as was observed for NMR.

CONCLUSIONS

Plasma is a very reliable biologic source for the determination of NMR, robust to differences in these analytical protocols or assessment site.

IMPACT

Together this indicates a reduced need for differential interpretation of plasma NMR results based on the approach used, allowing for direct comparison of different studies.

A single-day paradigm of self-regulated human cocaine administration

Prior work by our group has shown the feasibility, safety, and validity of a multi-day, multi-dose paradigm of self-regulated cocaine administration in humans. The current work sought to consolidate these methods in a single-day design focused on reducing logistical complexity, decreasing research burden to human subjects, and increasing suitability for medication development designs.

METHODS

Eleven experienced cocaine users participated in a 6-hour, single-day design, consisting of one safety/eligibility and three experimental cocaine periods (during which subjects were allowed to self-administer 8, 16, and 32 mg/70 kg cocaine doses under a fixed-ratio 1:5 minute timeout schedule). Changes in cocaine-induced cardiovascular response, self-administration behavior, and subjective effects were assessed.

RESULTS

Procedures were well tolerated by participants, and no significant adverse events were noted. Significant (p < 0.05), changes in measures of cocaine self-administration (e.g., responses, infusions, interinfusion intervals, consumption, and plasma levels), cardiovascular response (HR), and subjective effects (“high”) were observed. In contrast, cocaine-induced increases in other vital signs (e.g., SBP, DBP) and subjective effect measures (e.g., paranoia) did not differ between doses.

CONCLUSIONS

These data support the safety, tolerability and validity of our single-day design. Depending on the application, such methods may afford advantages for assessing the self-regulation of cocaine administration behavior in humans (e.g., including medication development designs).

Nicotine fails to attenuate ketamine-induced cognitive deficits and negative and positive symptoms in humans: implications for schizophrenia

BACKGROUND

The uncompetitive N-methyl-D-aspartate receptor (NMDAR) antagonist, ketamine, induces a range of symptoms resembling those seen in schizophrenia. Enhancement of nicotinic acetylcholine receptor (nAChR) function may have potential as a treatment for the cognitive deficits and negative symptoms of schizophrenia. Accordingly, we examined the modulatory effects of brain nAChR systems on NMDAR antagonist-induced effects.

METHODS

The interactive effects of ketamine and nicotine were evaluated in 37 healthy subjects in a randomized, placebo-controlled, double-blind, crossover counterbalanced, 2 (intravenous ketamine or placebo) × 2 (intravenous nicotine or placebo) design. Verbal and visual memory, sustained attention, working memory, response inhibition, emotion recognition, executive function, reaction time, motor function, and speed of processing were assessed once per test day, while negative and positive symptoms, perceptual alterations, and a number of feeling states were measured several times before and after administration of drugs.

RESULTS

Ketamine induced cognitive deficits and negative and positive symptoms. Nicotine worsened immediate recall, auditory working memory, response inhibition, and executive function and serial processing. Nicotine decreased (improved) reaction time on the sustained attention and choice reaction time tasks. Nicotine did not reduce ketamine-induced cognitive deficits or negative and positive symptoms.

CONCLUSIONS

At blood levels comparable with tobacco smoking, nicotine infusion does not appear to alleviate the ketamine-induced transient cognitive and behavioral effects in healthy subjects that resemble those seen in schizophrenia. The lack of an effect of nicotine on a spectrum of ketamine effects suggests that the consequences of NMDAR antagonism are not likely under the direct influence of nAChR.

Exploring the impact of gender and reproductive status on outcomes in a randomized clinical trial of naltrexone augmentation of nicotine patch

In a series of exploratory analyses, we examined the roles of gender, reproductive status and negative affect on smoking abstinence in subjects participating in a large (n=385) 6-week randomized clinical trial (RCT) of nicotine patch therapy, with varying doses of oral naltrexone (0mg, 25mg, 50mg, 100mg) treatment. Negative affect was assessed daily during the first post-quit week via telephone interactive voice response (IVR). Weight and adverse events were recorded weekly. In the intent to treat sample, the effects of dose on continuous abstinence were non-significant in the overall model for men and women. In the 295 study completers, there was a significant effect of dose on continuous abstinence in women only (F=8.53, p=0.04). In the 100mg group, 71% of women were continuously abstinent compared to 41% in the placebo group (p<0.05). Women in the active naltrexone groups gained less weight (F=2.91, df=3, p=0.04). Women in the 100mg vs. placebo group were less adherent with medication (F=3.19, p<0.05). These effects were not significant in men. Naltrexone treatment condition (100mg vs. placebo, p=0.02, odds ratio (OR)=0.28), gender (OR=0.55 p=0.09), and IVR ratings of negative affect (OR 1.02, p=0.04) predicted abstinence at Week 1 in study completers. Menstrual cycle status on quit day had a modest affect on abstinence. These data suggest that naltrexone dose, gender, and negative affect play a role in smoking abstinence, particularly in the early stages of treatment. When used in conjunction with nicotine replacement therapy, naltrexone dose may be important in women.

Low-dose naltrexone augmentation of nicotine replacement for smoking cessation with reduced weight gain: a randomized trial

BACKGROUND

Fear of weight gain is a significant obstacle to smoking cessation, preventing some smokers from attempting to quit. Several previous studies of naltrexone yielded promising results for minimization of post-quit weight gain. Given these encouraging findings, we endeavored to test whether minimization of weight gain might translate to better quit outcomes for a population that is particularly concerned about gaining weight upon quitting.

METHODS

Smokers (N=172) in this investigation were prospectively randomized to receive either 25 mg naltrexone or placebo for 27 weeks (1 week pre-, 26 weeks post-quit) for minimization of post-quit weight gain and smoking cessation. All participants received open label therapy with the nicotine patch for the first 8 weeks post-quit and behavioral counseling over the 27-week treatment. The 2 pre-specified primary outcomes were change in weight for continuously abstinent participants and biologically verified end-of-treatment 7-day point-prevalence abstinence at 26 weeks after the quit date.

RESULTS

The difference in weight at 26 weeks post-quit between the naltrexone and placebo groups (naltrexone: 6.8 lbs ± 8.94 vs placebo: 9.7 lbs ± 9.19, p = 0.45) was not statistically different. Seven-day point-prevalence smoking abstinence rates at 26 weeks post-quit was not significantly different between the 2 groups (naltrexone: 22% vs placebo: 27%, p = 0.43).

CONCLUSIONS

For smokers high in weight concern, the relatively small reduction in weight gain with low-dose naltrexone is not worth the potential for somewhat lower rates of smoking abstinence.

Clinical (nonforensic) application of ethyl glucuronide measurement: are we ready?

Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are minor metabolites of ethanol. Multiple studies have documented that, depending upon the amount of alcohol consumed, they can be measured in biological fluids for hours to days after the parent compound can no longer be detected. Testing for the presence of EtG, in a manner analogous to urinary drug abuse screening, has largely been restricted to forensic and law enforcement situations. Despite a real need for an objective and possibly quantitative marker of ethanol exposure for use in conjunction with outpatient clinical trials and treatment programs, measurement of these metabolites has seen only limited clinical application. The barriers to more extensive clinical use of EtG/EtS testing, particularly misleading assay results that can occur as a consequence of inadvertent exposure to nonbeverage ethanol-containing substances, are reviewed and put into perspective. Additional information needed to develop guidelines for optimal clinical utilization of EtG/EtS measurements is discussed.

Acute Cocaine Responses Following Cocaethylene Infusion

We report results of a randomized, double-blind, placebo-controlled, within-subject study (n = 8) to determine the ability of cocaethylene to modulate acute responses to cocaine and identify significant pharmacokinetic interactions between cocaine and cocaethylene. Stable plasma cocaethylene concentrations (0, 50, or 200 ng/ml) were maintained for 840 minutes. Cocaine (0, 0.25, or 0.5 mg/kg) was injected over 1 minute after 240 minutes of cocaethylene. Blood samples, subjective, and physiological measures were collected. No differences over baseline responses were observed following 240 minutes of a steady state cocaethylene infusion for cardiovascular or subjective responses. "Rush" duration following a cocaine challenge (0.5 mg/kg) declined when administered during the course of a 200 ng/mL cocaethylene infusion. (p = 0.01). No pharmacokinetic interaction occurred when cocaine was administered in conjunction with cocaethylene. Findings indicate that continuous 8-hour exposure to cocaethylene is safe, produces acute tolerance to itself, and reduces some behavioral effects of coadministered cocaine. Agonist substitution therapy may have potential as an alternative treatment for cocaine dependence.

Effects of the H3 receptor inverse agonist thioperamide on cocaine-induced locomotion in mice: role of the histaminergic system and potential pharmacokinetic interactions

RATIONALE

Previous studies have shown that intraperitoneal injections of thioperamide, an imidazole-based H3 receptor inverse agonist that enhances histamine release in the brain, potentiate cocaine-induced hyperlocomotion. The present study examined the involvement of the histaminergic system in these effects of thioperamide in mice.

MATERIALS AND METHODS

We investigated whether immepip, a selective H3 agonist, could reverse the potentiating effects of thioperamide. Moreover, the non-imidazole H3 inverse agonist A-331440 was tested on the locomotor effects of cocaine. Using high-performance liquid chromatography with ultraviolet detection, cocaine plasma concentrations were measured to study potential drug-drug interactions between thioperamide and cocaine. Finally, thioperamide was tested on the locomotor effects of cocaine in histamine-deficient knockout mice in order to determine the contribution of histamine to the modulating effects of thioperamide.

RESULTS

Thioperamide potentiated cocaine-induced hyperlocomotion in normal mice, and to a higher extent, in histamine-deficient knockout mice. A-331440 only slightly affected the locomotor effects of cocaine. Immepip did not alter cocaine-induced hyperactivity but significantly reduced the potentiating actions of thioperamide on cocaine's effects. Finally, plasma cocaine concentrations were more elevated in mice treated with thioperamide than in mice that received cocaine alone.

CONCLUSIONS

The present results indicate that histamine released by thioperamide through the blockade of H3 autoreceptors is not involved in the ability of this compound to potentiate cocaine induced-hyperactivity. Our data suggest that thioperamide, at least at 10 mg/kg, increases cocaine-induced locomotion through the combination of pharmacokinetic effects and the blockade of H3 receptors located on non-histaminergic neurons.

Comparison of expired carbon monoxide and plasma cotinine as markers of cigarette abstinence

The clinical pharmacology of biochemical measures of nicotine exposure has been thoroughly reviewed with regard to usefulness and limitations in detecting abstinence from cigarette smoking. While plasma nicotine concentration measures only acute nicotine exposure, plasma, salivary, and urine cotinine concentrations reflect exposure over an extended period of time. Although, expired carbon monoxide (CO) is frequently used to confirm self reports, it has a relatively short half life, calling into question whether this measure might provide misleading information by exaggerating smoking cessation success rates. To examine this question, we analyzed expired CO, plasma cotinine and self report data collected in a clinical trial in which subjects (N=207) were randomly assigned to gain- or loss-framed messages for smoking cessation in combination with open label sustained-release bupropion (300 mg/day). In examining measurements collected at 6 weeks, 3 and 6 months, results showed that CO significantly overestimated abstinence rates as compared with cotinine, although the discrepancy was less at the later time points. These data suggest that while expired CO is a useful and well-established marker in certain contexts, when testing extended abstinence from smoking with non-nicotine medications, cotinine measurements should be preferred.

Contingency management for smoking cessation: enhancing feasibility through use of immunoassay test strips measuring cotinine

Contingency management (CM) is a powerful behavioral intervention shown to reduce the use of a variety of substances including tobacco. Use of CM techniques for smoking cessation has been restricted by the use of multiple daily measurements of breath CO as the objective indicator to reinforce abstinence. Cotinine, with its longer half-life, may be a better marker. We evaluated the use of urinary cotinine (determined using once-daily semiquantitative immunoassay test strips and verified using quantitative GC/HPLC techniques) as an abstinence indicator in treatment-seeking adult and adolescent smokers participating in a CM-based intervention program. Both techniques of determining urinary cotinine were highly sensitive and moderately specific at detecting abstinence, and they were highly concordant. However, specificity was somewhat lower during the first few days of a quit attempt and improved over time. The results were similar in adults and adolescent smokers, and suggest that during the first few days of a quit attempt it would be advisable to continue to use daily multiple CO measurements to verify abstinence. However, once abstinence is achieved, once-daily immunoassay test strips could be used for continued monitoring of urinary cotinine levels. Immunoassay testing can identify individuals who relapse to smoking, though this study cannot evaluate whether the strips can identify resumption of abstinence. These results suggest that the use of cotinine as an abstinence indicator, by reducing the number of daily appointments, could significantly enhance the feasibility and utility of CM-based interventions for smoking cessation.

Comparing gain- and loss-framed messages for smoking cessation with sustained-release bupropion: a randomized controlled trial

Prospect theory suggests that because smoking cessation is a prevention behavior with a fairly certain outcome, gain-framed messages will be more persuasive than loss-framed messages when attempting to encourage smoking cessation. To test this hypothesis, the authors randomly assigned participants (N=258) in a clinical trial to either a gain- or loss-framed condition, in which they received factually equivalent video and printed messages encouraging smoking cessation that emphasized either the benefits of quitting (gains) or the costs of continuing to smoke (losses), respectively. All participants received open label sustained-release bupropion (300 mg/day) for 7 weeks. In the intent-to-treat analysis, the difference between the experimental groups by either point prevalence or continuous abstinence was not statistically significant. Among 170 treatment completers, however, a significantly higher proportion of participants were continuously abstinent in the gain-framed condition as compared with the loss-framed condition. These data suggest that gain-framed messages may be more persuasive than loss-framed messages in promoting early success in smoking cessation for participants who are engaged in treatment.

Factor structure and validity of the Medication Adherence Questionnaire (MAQ) with cigarette smokers trying to quit

The Medication Adherence Questionnaire (MAQ) is a scale used to evaluate adherence to medications. The present study assessed the factor structure and validity of the MAQ with cigarette smokers. A principal components analysis was conducted on MAQ scores from a sample of smokers presenting for treatment in a clinical trial of naltrexone and nicotine patch for smoking cessation (N = 385). Indices of convergent and predictive validity were tested using electronic medication caps for naltrexone, nicotine patch counts, plasma drug levels of naltrexone, and treatment outcomes. The principal components analysis revealed two factors. Factor 1, labeled "unintentional nonadherence," measured the extent to which individuals were nonadherent because they were careless or forgot to take their medications. Factor 2, labeled "purposeful nonadherence," assessed nonadherence related to purposefully stopping medication use after feeling better or worse. Only the second factor was shown to have good convergent and predictive validity. Specifically, this factor was related to pill-taking behavior measured with electronic medication caps and drug plasma levels and nicotine patch use based on nicotine patch count data, and it was associated with smoking cessation outcome. Thus the purposeful nonadherence factor of the MAQ may be used as a brief screening tool for medication adherence with cigarette smokers seeking treatment. Information obtained with this questionnaire could be used to counsel patients regarding the importance of medication adherence.

Interactions between buprenorphine and antiretrovirals. I. The nonnucleoside reverse-transcriptase inhibitors efavirenz and delavirdine

This study examined drug interactions between buprenorphine, an opioid partial agonist medication used in the treatment of opioid dependence, and the nonnucleoside reverse-transcriptase inhibitors (NNRTIs) efavirenz (EFV) and delavirdine (DLV). Opioid-dependent, buprenorphine/naloxone-maintained, human immunodeficiency virus (HIV)-negative volunteers (n=10 per NNRTI) participated in 24-h sessions to determine pharmacokinetics of buprenorphine and of buprenorphine with either EFV or DLV after administration of standard doses of either antiretroviral for 15 or 7 days, respectively. Opiate withdrawal symptoms, cognitive effects, and adverse events were determined before and after antiretroviral administration in opioid-dependent participants. The pharmacokinetics of NNRTIs in healthy control participants were used to determine the effect of buprenorphine on NNRTIs. EFV decreased the buprenorphine area under the concentration-time curve (P<.001). DLV increased buprenorphine concentrations (P<.001). Clinically significant consequences of these interactions were not observed. Buprenorphine did not alter antiretroviral pharmacokinetics. Adjustments of doses of either buprenorphine or EFV or DLV are not likely to be necessary when these drugs are administered for the treatment of opiate dependence and HIV disease.

Interactions between buprenorphine and antiretrovirals. II. The protease inhibitors nelfinavir, lopinavir/ritonavir, and ritonavir

We examined drug interactions between buprenorphine, an opioid partial agonist available by prescription for treatment of opioid dependence, and the protease inhibitors (PIs) nelfinavir (NFV), ritonavir (RTV), and lopinavir/ritonavir (LPV/R). Opioid-dependent, buprenorphine/naloxone-maintained, human immunodeficiency virus (HIV)-negative volunteers (n=10 per PI) participated in 24-h pharmacokinetic studies, before and after administration of each PI. Symptoms of opiate withdrawal and excess were determined before and after PI administration. PI pharmacokinetics were determined and compared between opiate-dependent participants and healthy control participants (n=15 per PI). Administration of RTV, but not of NFV or LPV/R, resulted in a significant increase in the buprenorphine area under the concentration-time curve (AUC). Symptoms of opiate excess, however, were not observed. Buprenorphine had no significant effects on PI AUC. Adjustments of doses of either buprenorphine or NFV, LPV/R, or RTV are not likely to be necessary when these drugs are administered for the treatment of opioid dependence and HIV disease.

Disulfiram effects on responses to intravenous cocaine administration

Disulfiram has been studied as a treatment for cocaine dependence. We report results of a randomized, double-blind, placebo-controlled, within-subject study to examine the interaction of disulfiram with intravenous cocaine.

METHODS

Non-treatment-seeking, cocaine-dependent, volunteers participated in serial experiments in which they received disulfiram placebo, 62.5 or 250 mg/day on days 1-6. On days 4-6, participants received a morning disulfiram dose 2 h prior to a scheduled session in which they were administered intravenous cocaine placebo, 0.25 mg/kg (n=9) or 0.5 mg/kg (n=3) over 1 min. Blood, cardiovascular and subjective measures were collected. Seven days of washout occurred between disulfiram conditions.

RESULTS

Following active disulfiram treatments and cocaine 0.25 mg/kg administration, plasma cocaine AUC (0-480 min) was increased (p=0.003 and 0.001) and cocaine clearance decreased (p<0.001). Disulfiram treatments also decreased cocaine clearance for the 0.5 mg/kg cocaine dose (p=0.002 and<0.001). Neither disulfiram dose with cocaine altered cardiovascular responses relative to cocaine alone. Following cocaine 0.25 mg/kg, 'any high' (p=0.021 and 0.019), 'cocaine high' (p=0.017 and 0.018) and 'rush' (p=0.013 and 0.047) significantly decreased with either disulfiram dose.

CONCLUSIONS

Disulfiram decreased cocaine clearance without toxicity. Cocaine 'high' and 'rush' were diminished. Disulfiram may be a promising pharmacotherapy in selected cocaine dependent individuals.

Human tobacco smokers in early abstinence have higher levels of beta2* nicotinic acetylcholine receptors than nonsmokers

Nicotine, the addictive chemical in tobacco smoke, initiates its actions in brain through nicotinic acetylcholine receptors (nAChRs). In particular, nAChRs containing beta2-subunits (beta2*-nAChRs) the most prevalent subtype, mediate the reinforcing properties of nicotine. We hypothesized that abnormal numbers of beta2*-nAChRs during early abstinence contribute to the perpetuation of addiction to tobacco smoking. Using molecular imaging, specifically single-photon emission computed tomography with the nAChR agonist radiotracer [123I]5-IA-85380 ([123I]5-IA), we imaged beta2*-nAChR availability in human smokers. First, using nonhuman primates treated chronically with nicotine, we estimated the time interval necessary for smokers to abstain from smoking so that residual nicotine would not interfere with [123I]5-IA binding to the beta2*-nAChR as approximately 7 d. Thus, we imaged human smokers at 6.8 +/- 1.9 d (mean +/- SD) of abstinence. Abstinence was confirmed by daily assessments of urinary cotinine and expired carbon monoxide levels. In smokers, [123I]5-IA uptake was significantly higher throughout the cerebral cortex (26-36%) and in the striatum (27%) than in nonsmokers, suggesting higher beta2*-nAChR in recently abstinent smokers. Beta2*-nAChR availability in recently abstinent smokers correlated with the days since last cigarette and the urge to smoke to relieve withdrawal symptoms but not the severity of nicotine dependence, severity of nicotine withdrawal, or the desire to smoke. Higher brain beta2*-nAChR during early abstinence indicates that, when smokers quit smoking, they do so in the face of a significant increase in the receptors normally activated by nicotine. Greater beta2*-nAChR availability during early abstinence may impact the ability of smokers to maintain abstinence.

A controlled trial of naltrexone augmentation of nicotine replacement therapy for smoking cessation

BACKGROUND

Many smokers remain refractory to current therapies, which only partially address weight gain after smoking cessation. Thus, this study evaluated whether naltrexone hydrochloride augmentation of nicotine patch therapy improves smoking abstinence and reduces postcessation weight gain more than nicotine patch therapy alone and at what dose.

METHODS

Six-week double-blind placebo-controlled trial with follow-up in an outpatient research center. Four hundred individuals who smoked 20 or more cigarettes daily were randomly assigned to treatment for 6 weeks with a 21-mg nicotine patch and oral naltrexone hydrochloride (0, 25, 50, or 100 mg/d) after equal random treatment assignment and followed up for 1 year after randomization. The a priori specified primary end points were prolonged 4-week cigarette abstinence after a 2-week grace period in the intent-to-treat sample and weight gain in these abstainers.

RESULTS

We found no significant differences in prolonged 4-week abstinence (P = .49) or 6-week continuous abstinence after the quit date (P = .12) during treatment in the intent-to-treat analysis. Among 295 treatment completers, the 100-mg dose was associated with higher continuous abstinence rates (71.6%) compared with placebo (48%) (odds ratio, 2.73; 95% confidence interval, 1.39-5.39; P<.01). Among continuous abstainers, the 25-mg naltrexone hydrochloride group gained significantly less weight (mean +/- SEM, 0.7 +/- 0.31 kg) than the placebo group (mean +/- SEM, 1.9 +/- 0.33 kg; P<.01). Similar naltrexone dose effects on weight were found for those with prolonged abstinence and treatment completers, irrespective of abstinence.

CONCLUSIONS

The 100-mg dose of naltrexone hydrochloride appears the most promising for augmenting the efficacy of the nicotine patch on smoking cessation outcomes but requires further study. The significant weight reduction with low-dose naltrexone therapy suggests that it may be useful as a second-line treatment for weight-concerned smokers.

Drug Interactions between Opioids and Antiretroviral Medications: Interaction between Methadone, LAAM, and Delavirdine

Understanding the drug interactions between antiretrovirals and opioid therapies may decrease toxicities and enhance adherence with improved HIV outcomes in opioid-dependent individuals. The authors report the results of a clinical pharmacology study designed to determine whether significant pharmacokinetic and/or pharmacodynamic interactions occur between the non-nucleoside reverse transcriptase inhibitor, delavirdine (DLV), and either methadone or levo-alpha acetyl methadol (LAAM) (n = 40). DLV significantly decreased methadone clearance (p = .018) and increased the methadone elimination half-life (p < .001) with a resultant increase in AUC of 19% and C(min)of 29%. The combined effect of DLV on the total concentration of LAAM and its active metabolites, norLAAM and dinorLAAM, was to significantly increase AUC by 43% (p < .001), C(max) by 30% (p = .013), and C(min) by 59% (p = .004) while decreasing T(max) (p = .05). Cognitive deficits over the seven-day study period as measured by the Mini-Mental State Examination, opioid withdrawal symptoms as measured by the Objective Opioid Withdrawal Scale, or complaints of adverse symptoms were not observed. Methadone and LAAM did not affect DLV concentrations. The findings from this study show that DLV treatment in methadone- or LAAM-maintained individuals results in altered opioid pharmacokinetics with an increased exposure and potential risk for opioid toxicity with methadone or LAAM treatment and an increased risk of cardiac toxicity with concomitant LAAM and DLV administration.

Cortical γ-Aminobutyric Acid Type A–Benzodiazepine Receptors in Recovery From Alcohol Dependence

CONTEXT

Adaptations in gamma-aminobutyric acid type A (GABA(A))-benzodiazepine receptors contribute to the neurobiology of human alcohol dependence and withdrawal.

OBJECTIVE

To study GABA(A)-benzodiazepine receptor adaptations in subjects with alcohol dependence over the first month of sobriety.

DESIGN

Inpatients who were not receiving medication, were either smokers or nonsmokers, and had alcohol dependence completed 2 iodine I 123-labeled iomazenil single-photon emission computed tomographic scans: 1 scan at a mean +/- SD of 4.9 +/- 2.5 days of sobriety (n = 23) and 1 scan at a mean +/- SD of 29.8 +/- 7.6 days of sobriety (n = 20). Participants in a matched group of healthy subjects (n = 15) completed 1 single-photon emission computed tomographic scan.

PARTICIPANTS

Men with alcohol dependence (n = 27) and a matched healthy comparison group (n = 15).

MAIN OUTCOME MEASURES

(123)I-iomazenil single-photon emission computed tomographic images were converted to units of distribution volume (regional activity/free (123)I-iomazenil) and were analyzed using voxel-based statistical parametric mapping and regions of interest analyses. The relationships between (123)I-iomazenil distribution volume, clinical features of alcohol dependence, and smoking status were evaluated.

RESULTS

(123)I-iomazenil uptake was elevated in several cortical regions, with a more prominent increase in nonsmokers with alcohol dependence as compared with smokers with alcohol dependence at 1 week of abstinence from alcohol. No significant differences were observed at 4 weeks of abstinence. At 1 week of abstinence, frontal (123)I-iomazenil uptake correlated with the severity of alcohol withdrawal and the number of days since the last alcoholic drink was consumed. No significant associations were observed for smokers with alcohol dependence.

CONCLUSIONS

These data demonstrate time-dependent regulation of cortical GABA(A)-benzodiazepine receptors associated with the recovery from alcohol dependence. Higher GABA(A)-benzodiazepine receptor levels during acute withdrawal may reflect a compensation for reduced receptor function, which is thought to contribute to alcohol tolerance and withdrawal. The subsequent decline may reflect "normalization" of GABA(A) receptor function with sobriety. Smoking may attenuate GABA(A) receptor adaptations associated with alcohol dependence and may contribute to the comorbidity between alcoholism and smoking.

A paradigm to investigate the self-regulation of cocaine administration in humans

INTRODUCTION

Current laboratory paradigms of human cocaine administration generally dictate the timing of drug access in ways that may limit assessing aspects of cocaine-taking behavior. Patient-controlled analgesia (PCA) methods, which allow individuals less restricted access to narcotic (i.e., opiate) analgesics, have proven safe and clinically effective for self-regulated treatment of pain. The current study assessed the feasibility, safety, and validity of a model of ad libitum cocaine self-administration, in which participants self-selected the timing of cocaine infusions, using PCA techniques.

METHODS

Eight nontreatment seeking, otherwise medically healthy, experienced cocaine users participated in a double-blind, placebo-controlled, escalating-dose regimen of intravenous cocaine (0, 8, 16, and 32 mg per 70 kg) on 4 test days, during which time participants had 2 h of access to cocaine via manual presses of a corded PCA pump button under a fixed ratio 1: time-out 5-min schedule.

RESULTS

Procedures were well-tolerated by participants, and no significant adverse events were noted. Measures of cocaine self-administration (e.g., number of responses and interinfusion intervals) indicated a significant main effect of cocaine dose, consistent with predicted dose-response relationships (i.e., decreasing responses and increasing interinfusion intervals with increasing injection dose). Participants appeared to regulate their cocaine intake in a carefully controlled manner, using considerably less cocaine (about half) that permitted by pump loading, PCA parameters, and session duration.

CONCLUSIONS

Data from this study support the validity of our PCA paradigm. Moreover, results suggest the apparent feasibility and safety of allowing experienced users to self-select the timing of cocaine infusions to intervals as short as 5 min. Such procedures may enhance our ability to identify effective pharmacological treatments for cocaine addiction.

Sex, GABA, and nicotine: the impact of smoking on cortical GABA levels across the menstrual cycle as measured with proton magnetic resonance spectroscopy

BACKGROUND

Given that nicotine modulates amino acid neurotransmission, we sought to examine the impact of nicotine on cortical gamma-aminobutyric acid (GABA) levels in male and female smokers.

METHODS

Healthy nicotine-dependent men (n = 10) and women (n = 6) underwent proton magnetic resonance spectroscopy (1H-MRS) to measure occipital cortex GABA concentrations. A subset of the smoking men (n = 5) underwent 1H-MRS scans before and after 48 hours of smoking abstinence, whereas each of the women were scheduled to undergo pre- and postabstinence scans during the follicular and luteal phases of one menstrual cycle. Healthy nonsmoking men (n = 7) and women (n = 13) underwent 1H-MRS for comparison.

RESULTS

Short-term abstinence had no significant effect on cortical GABA concentrations in either men or women. There was, however, a significant effect of sex, diagnosis (smoker/nonsmoker), and menstrual cycle phase on cortical GABA levels, such that female smokers experienced a significant reduction in cortical GABA levels during the follicular phase and no cyclicity in GABA levels across the menstrual cycle, whereas cortical GABA levels were similar in smoking and nonsmoking men.

CONCLUSIONS

Taken together with previous 1H-MRS data showing abnormalities in occipital cortex GABA concentrations in several affective disorders, our preliminary finding that nicotine modulation of GABA levels varies by sex provides a further rationale for investigating the impact of nicotine on central GABAergic function as a potential risk factor for women to experience depressive symptoms during smoking cessation.

Gender effects following repeated administration of cocaine and alcohol in humans

RATIONALE

Use of cocaine, alcohol, and the two drugs simultaneously is common and the risk of morbidity and mortality associated with these drugs is widely reported. This double-blind, placebo-controlled, randomized study examined gender differences in response to administration of these drugs alone and in combination.

METHODS

Current users of cocaine and alcohol (n = 17) who met diagnostic criteria (DSM-IV) for cocaine dependence and alcohol abuse or dependence (not physiologically dependent on alcohol) and who were not seeking treatment for substance use disorders gave voluntary, written, informed consent to participate in three drug administration sessions:1) four doses of intranasal cocaine (1 mg/kg every 30 min) with oral alcohol (1 g/kg following the initial cocaine dose and a second drink at +60 min (120 mg/kg) calculated to maintain a plasma alcohol concentration of approximately 100 mg/dL; 2)four doses of cocaine and alcohol placebo; 3) cocaine placebo and alcohol. Pharmacokinetics were obtained by serial blood sampling, physiological measurements (heart rate and blood pressure) were obtained with automated equipment, and subjective effects were assessed using visual analog scales over 480 min.

RESULTS

Responses to cocaine, alcohol, and cocaine-alcohol were equivalent by gender for most measurements. Women had higher heart rates following alcohol administration (p = .02). Women consistently reported higher ratings for "Feel Good:' a measure of overall mental/physical well-being, for all study conditions, reaching statistical significance for cocaine (p = .05) and approaching significance for alcohol administration (p = .1).

CONCLUSION

Women showed equivalent responses to drug administration with the exception of perception of well-being, which was significantly increased for women. These findings may have implications for differential risk for acute and chronic toxicity in women.

Altered NMDA glutamate receptor antagonist response in individuals with a family vulnerability to alcoholism

OBJECTIVE

A family history of alcoholism is a risk factor for the development of ethanol dependence. Ethanol is an antagonist of the N-methyl-d-aspartate (NMDA) glutamate receptor, and alterations in NMDA receptor function are thought to be involved in ethanol abuse and dependence. The purpose of this study was to determine in healthy individuals with no ethanol dependence whether response to the NMDA receptor antagonist ketamine would differentiate those with a family history of ethanol dependence from those without such a family history.

METHOD

Healthy subjects between the ages of 21 and 30 received 40-minute intravenous infusions of saline, low-dose ketamine (0.1 mg/kg), and high-dose ketamine (0.5 mg/kg) on three separate test days in a randomized order under double-blind conditions. The healthy individuals with at least one first-degree relative and another first- or second-degree relative with ethanol dependence (N=16) were compared with those who had no family history of ethanol dependence in any first- or second-degree relative (N=29). Outcome measures included the Brief Psychiatric Rating Scale, Clinician-Administered Dissociative States Scale, verbal fluency, Hopkins Verbal Learning Test, a biphasic alcohol effects scale, visual analog scales of mood states, and ketamine levels.

RESULTS

During ketamine infusion, individuals with a family history of ethanol dependence showed an attenuated response in terms of perceptual alterations and dysphoric mood relative to those without such a family history.

CONCLUSIONS

These data suggest that alterations in NMDA receptor function may contribute to subjective response to ethanol and therefore also to the risk of developing alcoholism.

Drug Interactions between Opioids and Antiretroviral Medications: Interaction between Methadone, LAAM, and Nelfinavir

Understanding drug interactions between antiretrovirals and opiate therapies may decrease toxicities and enhance adherence, with improved HIV outcomes in injection drug users. We report results of a clinical pharmacology study designed to examine the interaction of the protease inhibitor, nelfinavir, with methadone and LAAM (N = 48). Nelfinavir decreased methadone exposure, but no withdrawal was observed over the five day study period. LAAM and dinorLAAM concentrations were decreased, while norLAAM concentrations were increased, with minimal overall change in LAAM/metabolite exposure. Methadone and LAAM did not affect nelfinavir concentrations, but methadone decreased M8 metabolite exposure. While no toxicities were observed, clinicians should be aware of the potential for drug interactions when patients require treatment with nelfinavir and these opiate medications.

Sex differences in response to oral amitriptyline in three animal models of depression in C57BL/6J mice

RATIONALE

Knockout and transgenic mice provide a tool for assessing the mechanisms of action of antidepressants. The effectiveness of oral administration of the tricyclic antidepressant amitriptyline (AMI) was assessed in C57BL/6J (B6) mice, a common genetic background on which knockout and transgenic mice are maintained.

OBJECTIVES

We determined whether oral AMI would have antidepressant-like effects in B6 mice and whether these effects varied according to sex, duration of treatment, and the depression model utilized.

METHODS

Male and female B6 mice were administered AMI (200 microg/ml) in the drinking water as the sole source of fluid, along with 2% saccharin to increase palatability. Control mice were administered 2% saccharin alone. Mice were assessed for responsiveness to AMI in the tail suspension test (TST), the forced swim test (FST), and the learned helplessness (LH) paradigm.

RESULTS

In the TST, AMI decreased immobility time regardless of sex or duration of treatment. AMI also decreased immobility time in the FST, but chronic treatment was necessary for full efficacy in both sexes. In the LH paradigm, both subchronic and chronic AMI treatment decreased escape latencies in female mice, but AMI was effective only after chronic treatment in males. The antidepressant-like effects of AMI could not be explained by differences in locomotor activity because activity levels were not altered by antidepressant treatment.

CONCLUSIONS

Overall, oral AMI administration provides a valid model for behavioral assessment of antidepressant-like effects in knockout and transgenic mice maintained on a B6 background, but the effectiveness of oral AMI varies depending on sex, duration of treatment, and the depression model used.

The protease inhibitor lopinavir-ritonavir may produce opiate withdrawal in methadone-maintained patients

This study examines the pharmacokinetic/pharmacodynamic interactions between (1) lopinavir-ritonavir (L/R), a fixed combination of protease inhibitors used for the treatment of HIV disease, and (2) ritonavir alone at the same dosage as that in the L/R formulation, with methadone, an opiate frequently used in substance abuse pharmacotherapy for opioid (heroin)-dependent injection drug users, many of whom are infected with HIV. L/R was associated with significant reductions in the methadone area under the concentration-time curve (P<.001), maximum concentration (P<.001), and minimum concentration (P<.001), as well as increased methadone oral clearance (P<.001) and increased opiate withdrawal symptoms (P=.013), whereas ritonavir use alone modestly and nonsignificantly increased methadone concentrations. Lopinavir is a potent inducer of methadone metabolism, and treatment with L/R requires clinical monitoring and increased methadone doses in some patients, whereas ritonavir has no significant effect on methadone metabolism.

Modified directly observed therapy (MDOT) for injection drug users with HIV disease

Injection drug use is an important factor in the spread of HIV infection, and strategies to enhance adherence to HIV therapeutics are critically important to controlling viral transmission and improving clinical outcomes. To this end, the authors sought (1) to enhance adherence to highly active antiretroviral therapy (HAART) among methadone-maintained injection drug users (IDUs) using modified directly observed therapy (MDOT), and (2) to define interactions between methadone and HAART and the potential contribution of drug interactions to adherence and HIV outcomes in this population. Adherence was explored here through a pilot, unblinded, 24-week study in a methadone maintenance program in which simplified HAART (efavirenz and didanosine [one daily] and a second nucleoside [twice daily]) was administered 6 days/week by clinic staff to HIV-infected IDUs (n = 5) with their methadone. Evening doses of riboflavin-tagged nucleoside and one full day of medication weekly were given as take home doses. As a result of HAART administration, four of five participants with mean viral load at baseline of 10(5) copies/ml had undetectable viral load by 8 weeks of treatment (p = .043). Methadone area under the curve (AUC) decreased by 55% (p = .007) within 2 weeks of initiating this HAART regimen, and a mean methadone dose increase of 52% was required. The authors conclude that MDOT is a promising intervention for the treatment of IDUs with HIV disease, though significant drug interactions must be monitored for carefully and rapidly addressed.

The pharmacokinetics of methadone following co-administration with a lamivudine/zidovudine combination tablet in opiate-dependent subjects

Methadone pharmacokinetics were determined in an open-label, within subject study in 16 methadone-maintained, non-HIV-infected subjects prior to and following administration of one lamivudine 150-mg/zidovudine 300-mg combination tablet to determine whether this antiretroviral therapy alters methadone serum concentrations. No significant differences in the mean area under the serum concentration-time curve (AUC(0-24h); 8,753 +/- 4,280 vs. 8,641 +/- 4,431 microg-h/L),oralclearance(CL/F;9.9 +/- 4.9vs. 10.3 +/- 5.5 L/h),oral volume of distribution (Vd/F; 647 +/- 465 vs. 481 +/- 305 L), maximum serum concentration (Cmax; 514 +/- 223 vs. 5,510 +/- 237 microg/L), or terminal elimination half-life (t 1/2; 55.3 +/- 61.0 vs. 35.0 +/- 17.5 h) were detected. These results suggest that methadone dose change is not likely to be necessary for patients treated with lamivudine/zidovudine combination pharmacotherapy.

Effect of opioid dependence pharmacotherapies on zidovudine disposition

Injection drug users are frequently infected with human immunodeficiency virus (HIV) and receive opioid dependence pharmacotherapies and zidovudine (ZDV), the latter as a component of highly active antiretroviral therapy. We previously reported that methadone substantially increases ZDV concentrations. We now report on oral ZDV pharmacokinetics in 52 subjects receiving the opioid dependence pharmacotherapies l-alpha-acetylmethadol LAAM, buprenorphine, or naltrexone, and 17 non-opioid-treated controls. Relative to the area under the time-concentration curve (AUC) of ZDV in control subjects, no statistically significant differences in ZDV AUC were observed in participants treated with LAAM (p = .75), buprenorphine (p = .37), or naltrexone (p = .34). While methadone maintenance may result in ZDV toxicity and possibly require dose adjustments, other opioid pharmacotherapies should not produce ZDV toxicity.

Impact of intravenous nicotine on BOLD signal response to photic stimulation

Functional magnetic resonance imaging (fMRI) is increasingly being applied in the study of brain effects of nicotine. In addition, because tobacco smoking is common, many subjects studied with fMRI for other reasons may have appreciable levels of nicotine in plasma and brain during scanning. However, there is concern that the vascular effects of nicotine may alter the coupling between blood oxygen level dependent (BOLD) signal and neuronal activity. The objective of this study was to test for evidence of alteration of BOLD signal response of occipital cortex, a region with a relatively low concentration of neuronal nicotine receptors, to photic stimulation during intravenous infusion of nicotine. Nine nicotine dependent healthy smokers were withdrawn from nicotine under controlled conditions and then scanned while receiving photic stimulation and successive intravenous infusions of saline and nicotine. No evidence for an effect of nicotine on BOLD signal response to photic stimulation was detected at the doses studied. This observation suggests that nicotine does not alter the coupling between BOLD signal and neuronal activity in the visual cortex.

Maternal sertraline treatment and serotonin transport in breast-feeding mother-infant pairs

OBJECTIVE

Pharmacological treatment of postpartum depression is frequently complicated by the mother's desire to breast-feed. Although breast milk levels of several selective serotonin reuptake inhibitors (SSRIs) have been reported to be relatively low, a critical question is whether SSRI exposure during nursing results in clinically significant blockade of serotonin (5-HT) reuptake in infants. This study determined the degree of transporter blockade in infants exposed to sertraline through maternal breast milk.

METHOD

The extent of maternal and infant transporter blockade was assessed by measurement of platelet levels of 5-HT in 14 breast-feeding mother-infant pairs before and after 6-16 weeks of maternal treatment with sertraline for major depression with postpartum onset. Plasma sertraline and desmethylsertraline levels were obtained in 13 of these mothers and 11 of their infants.

RESULTS

Marked declines in platelet 5-HT levels of 70%-96% were observed in mothers after sertraline treatment, 25-200 mg/day. In contrast, infants showed little or no change in platelet 5-HT levels after exposure through breast-feeding. Mean levels of maternal plasma sertraline and its major metabolite, desmethylsertraline, were 30.7 ng/ml and 45.3 ng/ml, respectively. Drug and drug metabolite concentrations in the infants were at or below the lower limit of quantitation.

CONCLUSIONS

The data indicate that while mothers receiving clinical doses of sertraline experience substantial blockade of the platelet 5-HT transporter, platelet 5-HT uptake in nursing infants of treated mothers is unaltered. The observations suggest that mothers taking sertraline can breast-feed without appreciably affecting peripheral or central 5-HT transport in their infants.

Dark Agouti and Fischer 344 rats: differential behavioral responses to morphine and biochemical differences in the ventral tegmental area

We sought to identify behavioral and biochemical differences between Dark Agouti and Fischer 344 inbred rat strains to assess whether they could serve as a model of genetically determined differences in sensitivity to drugs of abuse. We compared the strains for the following traits: morphine-induced locomotor activity and sensitization; circadian variation in plasma levels of corticosterone, a hormone reported to affect sensitivity to drugs of abuse; and several biochemical parameters in the ventral tegmental area and nucleus accumbens, brain regions implicated in the locomotor activating and reinforcing actions of drugs of abuse. Fischer 344 rats exhibited greater initial locomotor responses to morphine but, unlike Dark Agouti rats, did not develop sensitization to a second morphine exposure. Fischer 344 rats displayed a marked rise in basal plasma corticosterone levels in the late light phase and early dark phase, whereas Dark Agouti rats showed no significant circadian variation in corticosterone levels. Relative to drug-naive Fischer 344 rats, drug-naive Dark Agouti rats showed higher levels of tyrosine hydroxylase and glial fibrillary acidic protein, and lower levels of neurofilament proteins, in the ventral tegmental area. In contrast, no strain differences were found in levels of tyrosine hydroxylase, specific G protein subunits or protein kinase A in the nucleus accumbens. Together, these results demonstrate that Dark Agouti rats and Fischer 344 rats exhibit differences in specific behavioral, endocrine and biochemical parameters related to sensitivity to drugs of abuse.

Impact of self-administered cocaine and cocaine cues on extracellular dopamine in mesolimbic and sensorimotor striatum in rhesus monkeys

Studies were conducted to determine the impact of self-administered cocaine on extracellular striatal dopamine in four rhesus monkeys. The extent to which external cue conditioning contributed to the effects of cocaine and whether there is activation of striatal dopaminergic neurotransmission during drug-seeking behavior was also examined. Microdialysis measurements were made at 2 min intervals in sensorimotor (dorsolateral) and mesolimbic (central and ventromedial) striatum. A fixed-ratio schedule of reinforcement was used, with cocaine availability signaled by a visual cue. Studies examined the effects of cocaine or cocaine cues against a drug-free baseline. Large (fivefold to eightfold) increases in extracellular dopamine after a self-administered infusion of 0.5 mg/kg cocaine were quite rapid and matched the time course of reported subjective effects in human laboratory studies. To determine if conditioning to external cues contributed to the cocaine-induced increases, saline was substituted for cocaine in the infusion, leaving all other visual and auditory stimuli unchanged. No increase in extracellular dopamine in either sensorimotor or mesolimbic striatal subdivisions was observed. Extracellular dopamine during extended periods of drug-seeking behavior triggered by a visual cue was determined in both central and ventromedial striatum. This procedure also did not result in any measurable changes in extracellular dopamine. These studies demonstrate rapid and pronounced pharmacological actions of self-administered cocaine. No apparent conditioned component of those actions was associated with external environmental cues, suggesting that cues that trigger drug-seeking behavior in nonhuman primates do not cause conditioned increases in mesolimbic striatal dopamine.

Significant interaction between clozapine and cocaine in cocaine addicts

Because clozapine may be prescribed to cocaine abusing patients with schizophrenia, we studied cocaine-clozapine interactions in a controlled setting. Eight male cocaine addicts underwent four oral challenges with ascending doses of clozapine (12.5, 25 and 50 mg) and placebo followed 2 h later by a 2-mg/kg dose of intranasal cocaine. Subjective and physiological responses, and serum cocaine levels were measured over a total 4-h period. Clozapine pretreatment increased cocaine levels during the study and significantly increased the peak serum cocaine levels in a dose dependent manner. In spite of this elevation in blood levels, clozapine pretreatment had a significant diminishing effect upon subjective responses to cocaine, including 'expected high', 'high' and 'rush', notably at the 50 mg dose. There was also a significant effect upon 'sleepiness', 'paranoia' and 'nervous'. Clozapine caused a significant near-syncopal episode in one subject in the study, requiring his removal from the study. Clozapine had no significant effect on baseline pulse rate and systolic blood pressure, but it attenuated the significant pressor effects of the single dose of intranasal cocaine. These data suggested a possible therapeutic role for clozapine in the treatment of cocaine addiction in humans, but also suggests caution due to the near-syncopal event and the increase in serum cocaine levels.

Comparison of intravenous cocaethylene and cocaine in humans

RATIONALE

Cocaethylene is a pharmacologically active homolog and metabolite of cocaine, formed by transesterification of cocaine in the presence of ethanol. Here we relate findings from a randomized, placebo-controlled, double-blind study in which we examined the physiological and subjective effects and pharmacokinetics of i.v. administered cocaethylene in human volunteers using cocaine as a comparator.

METHODS

Cocaine-dependent participants randomly received one study drug, cocaethylene (0.25 or 0.5 mg/kg), cocaine (0.25 or 0.5 mg/kg), or placebo, during each experimental session which occurred on separate days.

RESULTS

Cocaethylene was less potent in elevating heart rate than equivalent doses of cocaine. Similar differences between cocaine and cocaethylene were found for subjective measures ("Cocaine High", "Rush", "Stimulated" and "Good Drug Effects"). All active drug conditions produced significant increases in systolic blood pressure relative to placebo, but no significant effect on diastolic blood pressure was observed. Cocaethylene demonstrated a slower clearance, larger volume of distribution and correspondingly longer elimination half-life than cocaine.

CONCLUSION

The findings from this study confirm those of previous studies that show that cocaethylene has pharmacological properties in common with cocaine, but is less potent.

Desipramine in opioid-dependent cocaine abusers maintained on buprenorphine vs methadone

BACKGROUND

Cocaine abuse occurs in 40% to 60% of patients entering opioid maintenance treatment, and effective pharmacotherapies are needed for this combined dependence.

METHODS

This 13-week, randomized, double-blind, placebo-controlled trial evaluated the efficacy of desipramine hydrochloride (0 or 150 mg/d) plus buprenorphine hydrochloride (12 mg/d) or methadone hydrochloride (65 mg/d) in 180 opioid-dependent cocaine abusers (124 men, 56 women). Supervised urine samples were obtained thrice weekly, and self-reported cocaine and heroin use was reported once weekly. Desipramine plasma levels were determined at weeks 4 and 10.

RESULTS

In men, opioid abstinence was increased more rapidly over time when treated with methadone than with buprenorphine, whereas cocaine abstinence was increased more with buprenorphine than with methadone. In women, opioid abstinence was increased the least rapidly when treated with buprenorphine plus placebo, while cocaine abstinence was increased more rapidly over time when treated with methadone than with buprenorphine. Regardless of sex or opioid medication, desipramine increased opioid and cocaine abstinence more rapidly over time than placebo. Self-reported opioid use confirmed these findings. Desipramine plasma levels were higher in women than in men, particularly those on buprenorphine maintenance. Higher desipramine plasma levels were associated with greater opioid, but not cocaine, abstinence.

CONCLUSIONS

Desipramine may be a useful adjunctive medication in facilitating opioid and cocaine abstinence in opioid-maintained patients. The efficacy of opioid medications to treat opioid or cocaine dependence may differ by sex. These findings highlight the importance of including sex as a factor when examining treatment outcome in these types of trials.

Rapid induction of behavioral and neurochemical tolerance to cocaethylene, a model compound for agonist therapy of cocaine dependence

RATIONALE

Tolerance to abused drugs may impact on patterns of abuse, and in the case of agonist therapies, may be beneficial in that it reduces the reward value of a given dose of abused drug. Cocaethylene, a psychoactive metabolite resulting from concurrent alcohol and cocaine consumption, was examined because of its use in human research studies of drug reward mechanisms, and its potential as a model compound for an agonist based therapy for cocaine dependence.

OBJECTIVE

Comparisons were made between cocaine and cocaethylene in the acute development of tolerance to the neurochemical and behavioral effects of cocaine. With chronic exposure, tolerance to the behavioral effects of cocaine was examined.

METHODS

In awake rats with a microdialysis probe in the nucleus accumbens and a jugular catheter, an IV bolus/3-h infusion of cocaine or cocaethylene and a subsequent cocaine challenge was administered while extracellular dopamine and locomotion were monitored. Chronic IV treatment with cocaine, cocaethylene, and a water control was accomplished for 7 days using osmotic minipumps attached to jugular catheters. Animals were then challenged with an IV bolus of cocaine.

RESULTS

With acute treatment, the IV bolus of cocaethylene at the beginning of the infusion period resulted in an initial behavioral activation equivalent to that caused by cocaine, after which there was a striking difference in that the cocaethylene group displayed a return to predrug levels of activity, while the cocaine group showed high levels of activity throughout the 3-h period. Both cocaethylene and cocaine resulted in an initial increase in the extracellular concentration of dopamine. However, after that initial increase, levels of dopamine dropped in the cocaethylene group while the cocaine group levels remained elevated. A 1-week infusion of cocaine or cocaethylene resulted in tolerance to the behavioral activating effects of a subsequent cocaine challenge.

CONCLUSIONS

These results demonstrate a rapid induction of tolerance to the behavioral and neurochemical properties of cocaethylene, resulting in a diminished behavioral response to a cocaine challenge both acutely, and after 7 days. The relevance of these data for the use of cocaethylene as a model compound for an agonist approach to therapy for cocaine dependence is discussed.

Naltrexone and morphine alter the discrimination and plasma levels of ethanol

The opioid antagonist, naltrexone, reduces intake of, and operant responding for, ethanol, but reports of how the opioid agonist morphine alters these effects are conflicting. We examined the discrimination and plasma levels of ethanol with naltrexone and morphine pretreatments. Rats were trained to discriminate ethanol (1.5 g/kg; i.g.) from water, under a two-lever, food-reinforced procedure. Ethanol and pentobarbital, but not amphetamine, substituted for ethanol in a dose-related manner. Naltrexone reduced ethanol-induced, ethanol-appropriate responding to about 35%, but the peripherally-acting antagonist, naltrexone methobromide, was without effect. Morphine neither substituted for nor enhanced ethanol-appropriate responding. Rather, ethanol-induced, ethanol-appropriate responding was attenuated in a dose-related manner by morphine administration. Neither naltrexone nor morphine altered ethanol-appropriate responding to the substitution with pentobarbital. In another group of rats, both naltrexone and morphine decreased plasma ethanol levels, and delayed the time of peak concentrations, suggesting that opiates alter the behavioral effects of ethanol through both pharmacokinetic and pharmacodynamic mechanisms. The similarities between an opioid agonist and an antagonist suggest that either naltrexone has opioid agonist-like effects, or that these effects occur through non-opioidergic mechanisms.

Disulfiram effects on acute cocaine administration

Disulfiram (Antabuse) is being used in outpatient clinical trials to determine its efficacy as a treatment for cocaine dependence. This inpatient randomized, double-blind, placebo-controlled, within-subjects study was conducted to determine whether disulfiram (placebo, 250 or 500 mg/day) alters responses to acute intranasal cocaine (placebo, 1 or 2 mg/kg) administration. Effects of disulfiram on cocaine pharmacokinetics, physiological, and behavioral responses were determined. Disulfiram treatment increased plasma cocaine concentrations three to six times and significantly increased cocaine-associated cardiovascular responses, but did not significantly alter behavioral responses to cocaine. These interactions should be considered in the decision regarding disulfiram treatment in cocaine dependent patients.

Lithium and desipramine versus desipramine alone in the treatment of severe major depression: a preliminary study

Improvement following lithium augmentation is well-documented in depressed patients resistant to tricyclic antidepressants. However, response latency to lithium augmentation is extremely variable, suggesting other mechanisms may be involved. To evaluate whether long-term tricyclic treatment is necessary for lithium augmentation's effect, the rapidity and magnitude of response to lithium combined with desipramine from the start of treatment was compared to desipramine alone in severely depressed patients. Patients with DSM-III-R major depression were randomized to double-blind, placebo-controlled treatment with either lithium + desipramine or placebo + desipramine for 4 weeks. Response criteria were based on Hamilton Depression Rating Scale scores and global improvement. Analysis of covariance of Hamilton scores demonstrated that lithium + desipramine was superior to placebo + desipramine at week 1 (P < 0.009), week 2 (P < 0.028), and week 3 (P < 0.07), although not at week 4. There were more responders to the combination than to monotherapy (P < 0.042). These preliminary data suggest that lithium + desipramine may have some efficacy in severely depressed patients. Further studies with larger samples are needed to confirm these findings.