Psychedelics: Threshold of a Therapeutic Revolution

This Special Issue of Neuropharmacology on psychedelics provides a timely and comprehensive update on progress following the previous Neuropharmacology Special Issue "Psychedelics: New Doors, Altered Perceptions". Remarkable advances have been made in basic and clinical research on psychedelics in the five years since 2018. It is partly based on the seminar series focused on psilocybin organized by the National Institutes of Health (NIH), USA from April to June 2021, the "NIH Psilocybin Research Speaker Series". Participants were world leading experts, including scientists, medical practitioners, clinical psychologists and oncologists, and attendees from additional disciplines of patient advocacy, law, government science policy and regulatory policy. To provide a global perspective, their contributions are complemented with reviews by some of the world's most eminent scientists in the field. The US Food and Drug Administration (FDA) has granted two breakthrough therapy designations for psilocybin in treatment resistant depression (TRD) in 2018 and major depressive disorder (MDD) in 2019, as well as for MDMA for the treatment of post-traumatic stress disorder (PTSD) in 2017. Clinical trials are in progress to assess the therapeutic value of psilocybin in MDD and TRD, and in other indications such as cancer-related anxiety and depression, anorexia, PTSD, substance use disorders and various types of chronic pain. The contributors' insights should assist basic and applied science for transition of psychedelics from bench to potential mainstream therapies. The implications are global, because FDA approval of these new medicines will increase international interest and efforts.

Brand differences of free-base nicotine delivery in cigarette smoke: the view of the tobacco industry documents

The recent availability of internal tobacco industry documents provides significant insight into industry knowledge and manipulation of tobacco smoke delivery. One critical area of research is the role of smoke chemistry in determining the absorption and effects of smoke constituents, especially harm producing or pharmacologically active compounds. Independent scientific research has suggested that the nicotine dosing characteristics, hence the addiction potential of cigarettes, may be determined in part by the amount of free-base nicotine in cigarette smoke and its effects on the location, route, and speed of absorption in the body and on the sensory perception effects of the inhaled smoke. Tobacco industry documents describe the use of a number of methods internally for measuring free-base nicotine delivery. These include the common use of cigarette "smoke pH" as a means to estimate the fraction of free-base nicotine in the particulate matter (PM) in cigarette smoke, as well as efforts to measure free-base nicotine directly. Although these methods do not provide accurate absolute measures of free-base nicotine in smoke, consistencies observed in the findings across the various manufacturers indicate: (1) real relative differences in the acid/base chemistry of the smoke from different brands of cigarettes; (2) a connection between differences in free-base levels and brand-dependent differences in sensory perception and smoke "impact"; and (3) levels of free-base nicotine that are greater than have typically been publicly discussed by the industry. Furthermore, the results of these methods are generally consistent with those of a recent study from the Centers for Disease Control and Prevention which directly measured the free-base fraction of nicotine across a range of cigarette types. Consideration of the likely fundamental importance of free-base nicotine levels in cigarette smoke, together with the efforts discussed in the tobacco industry documents to measure such levels, indicates that the public health community would benefit from additional research to assess directly the delivery of free-base nicotine in cigarette smoke across brands. This may be especially useful for those products ("light", "ultralight", "reduced carcinogen", etc) that have been promoted, either explicitly or implicitly, as "harm reducing".

Toward a comprehensive long term nicotine policy

Global tobacco deaths are high and rising. Tobacco use is primarily driven by nicotine addiction. Overall tobacco control policy is relatively well agreed upon but a long term nicotine policy has been less well considered and requires further debate. Reaching consensus is important because a nicotine policy is integral to the target of reducing tobacco caused disease, and the contentious issues need to be resolved before the necessary political changes can be sought. A long term and comprehensive nicotine policy is proposed here. It envisages both reducing the attractiveness and addictiveness of existing tobacco based nicotine delivery systems as well as providing alternative sources of acceptable clean nicotine as competition for tobacco. Clean nicotine is defined as nicotine free enough of tobacco toxicants to pass regulatory approval. A three phase policy is proposed. The initial phase requires regulatory capture of cigarette and smoke constituents liberalising the market for clean nicotine; regulating all nicotine sources from the same agency; and research into nicotine absorption and the role of tobacco additives in this process. The second phase anticipates clean nicotine overtaking tobacco as the primary source of the drug (facilitated by use of regulatory and taxation measures); simplification of tobacco products by limitation of additives which make tobacco attractive and easier to smoke (but tobacco would still be able to provide a satisfying dose of nicotine). The third phase includes a progressive reduction in the nicotine content of cigarettes, with clean nicotine freely available to take the place of tobacco as society's main nicotine source.

Reducing tobacco addiction through tobacco product regulation

Tobacco product regulation has the potential to help reduce tobacco attributable disease by reducing the toxicity of these products and by reducing the prevalence of tobacco use and addiction.

Regulatory strategies to reduce tobacco addiction in youth

Preventing tobacco addiction and achieving cessation in established users are the cornerstones of efforts to reduce tobacco use and disease. It has been increasingly recognised that reducing tobacco toxin exposure has theoretical potential to reduce disease in continuing tobacco users. This has been controversial because such approaches also carry the potential to undermine prevention and cessation. As complicated as harm reduction issues are for adults, they are still more complicated for youth. Harm reduction is not a singular approach, but rather a concept that encompasses an extremely diverse array of potential approaches. These carry equally diverse potential risks and benefits. The regulatory framework (for example, whether or not the Food and Drug Administration regulates the approach) is also predicted to be a major factor in determining the consequences of harm reduction approaches. This paper examines the various issues and potential approaches concerning the application of harm reduction to youth. We conclude that although some carry great risk, others may actually support broader tobacco control efforts to prevent tobacco use and foster cessation in youth and adults.

Tobacco use as drug addiction: the scientific foundation

Tobacco use is strongly driven by the pharmacological actions of nicotine in the central nervous system. This review will summarize some of the seminal research findings relating to nicotine dependence and will highlight fundamental questions that must yet be answered. The evidence that nicotine is an addictive drug was summarized in the 1988 Report of the Surgeon General which concluded that nicotine fulfills the criteria for a dependence-producing drug. More recently, research has further characterized the pharmacological effects of nicotine in the brain and elucidated the basic pathophysiology of nicotine addition. Moreover, research shows that nicotine replacement therapy, such as nicotine patch or gum, can prevent or reverse withdrawal symptoms. It is also clear that the form of nicotine delivery is a major determinant of addiction potential and that cigarettes and smokeless tobacco products are both highly engineered drug delivery devices that act not only to provide users with controllable doses of nicotine, but also to maximize the addictive effects of nicotine. Along with the understanding of the dependence process has come a rapidly expanding arsenal of treatment for the disorder. There are many major questions about the nature and course of nicotine addiction that remain unanswered and must be addressed if we are to continue to improve our ability to prevent tobacco dependence as well as to provide more effective and acceptable options for treatment and disease prevention in those who are already addicted.

Correlates of expired air carbon monoxide: effect of ethnicity and relationship with saliva cotinine and nicotine

AIMS

To assess the accuracy of expired air carbon monoxide (CO) measurement vs. saliva cotinine and nicotine and to estimate the degree of misclassifications of smoking status as a function of ethnicity.

DESIGN AND MEASUREMENTS

Comparison for accuracy of expired air CO, saliva nicotine and cotinine in simultaneously collected specimens.

SETTING

Outpatient clinic of a clinical research ward.

PARTICIPANTS

228 current African-American and Caucasian cigarette smokers.

RESULTS

Expired-air CO concentration was significantly associated with saliva cotinine, but not with saliva nicotine. Saliva cotinine but not expired CO or saliva nicotine showed a significant between-ethnic difference when adjusted for number of cigarettes smoked and for time since last cigarette. Agreement between expired air CO and saliva cotinine was substantial at expired CO < or = 8 ppm but only moderate at < or = 10 ppm. False negative rates were twice as high at < or = 10 ppm than at < or = 8 ppm at each saliva cotinine cut-off tested. At saliva cotinine of < or = 15 ng/ml, more African-Americans were classified as false negative.

CONCLUSIONS

Expired CO is strongly associated with saliva cotinine but not with saliva nicotine. Despite this association, misclassifications for no smoking are frequent if true classification is based on saliva cotinine. False negative results occur more frequently in African-Americans.

Combination nicotine replacement therapy for smoking cessation: rationale, efficacy and tolerability

Currently available nicotine replacement therapy (NRT) medications provide effective treatment for tobacco dependence, typically doubling success rates compared with placebo. A strategy for further improving the efficacy of NRT is to combine one medication that allows for passive nicotine delivery (e.g. transdermal patch) with another medication that permits ad libitum nicotine delivery (e.g. gum, nasal spray, inhaler). The rationale for combining NRT medications is that smokers may need both a slow delivery system to achieve a constant concentration of nicotine to relieve cravings and tobacco withdrawal symptoms, as well as a faster acting preparation that can be administered on demand for immediate relief of breakthrough cravings and withdrawal symptoms. This article reviews 5 published studies that have examined the effectiveness of combination NRT compared with monotherapy in providing withdrawal relief and smoking cessation, and examines other factors relevant to the promotion of combination NRT for treating tobacco dependence. The data show that there are conditions under which combinations of NRT products provide greater efficacy in relieving withdrawal and enabling cessation than monotherapy, but the findings are not robust and additional research is warranted to better understand the magnitude and generality of the benefits of combination therapy. There are also regulatory and commercial obstacles that must be considered. Nonetheless, combination NRT has the potential to provide effective treatment of tobacco dependence in persons whose dependence is refractory to currently available treatments.

Tobacco addiction and pharmacological interventions

Even though its health consequences are well known, tobacco use continues to kill millions of smokers worldwide every year. In the US alone, tobacco use kills > 430,000 people each year. The global mortality toll is approximately 5 million annually and this is increasing. It is the powerful grip of tobacco addiction that sustains high levels of daily smoke intake and persistent smoking, with > 90% of all cigarette smokers who quit, resuming smoking within 1 year. Tobacco addiction, which places tremendous health and economic burdens on individual societies, is also becoming a global epidemic. Although tobacco addiction is a complex phenomenon, it is treatable and several effective medications are now available. In the mid-1980s, the US FDA approved nicotine gum, the first of these effective pharmacological aids. Other effective medications have subsequently become available, including nicotine transdermal patches, nasal spray, oral vapour inhaler, sublingual nicotine tablets and bupropion. These medications and the potential for development of new medications will be reviewed.

Effect of nicotine on brain activation during performance of a working memory task

Nicotine influences cognition and behavior, but the mechanisms by which these effects occur are unclear. By using positron emission tomography, we measured cognitive activation (increases in relative regional cerebral blood flow) during a working memory task [2-back task (2BT)] in 11 abstinent smokers and 11 ex-smokers. Assays were performed both after administration of placebo gum and 4-mg nicotine gum. Performance on the 2BT did not differ between groups in either condition, and the pattern of brain activation by the 2BT was consistent with reports in the literature. However, in the placebo condition, activation in ex-smokers predominated in the left hemisphere, whereas in smokers, it occurred in the right hemisphere. When nicotine was administered, activation was reduced in smokers but enhanced in ex-smokers. The lateralization of activation as a function of nicotine dependence suggests that chronic exposure to nicotine or withdrawal from nicotine affects cognitive strategies used to perform the memory task. Furthermore, the lack of enhancement of activation after nicotine administration in smokers likely reflects tolerance.

A factor analysis of the fagerstrom tolerance questionnaire

A factor analysis of 1309 Fagerstrom Tolerance Questionnaires (FTQ) was performed with LISCOMP software, which utilizes tetrachoric correlations to account for the dichotomous responses of the FTQ. Three factors with eigenvalues greater than 1.0 were obtained, accounting for 56.6% of the variance. Factor 1 was loaded by questions "How soon on waking do you smoke your first cigarette?," "Do you find it difficult to refrain from smoking in places it is forbidden?," "How many cigarettes a day do you smoke?," and "Do you smoke if you are so ill that you are in bed most of the day?" Factor 2 was loaded by questions "Which cigarette would you hate to give up?" and "Do you smoke more during the morning than during the rest of the day?" Factor 3 was loaded exclusively by question "What brand do you smoke?" The question "Do you inhale always, sometimes, or never?" loaded exclusively on a fourth factor, however its eigenvalue did not reach significance. Support is provided for the modification of the eight-item FTQ to the six-item Fagerstrom Test for Nicotine Dependence (FTND). Based on the wording of the questions that loaded on each factor, we propose that Factor 2 assesses the degree of urgency to initiate smoking after overnight abstinence and that Factor 1 reflects the persistence of smoking during waking hours.

Prevention of nicotine addiction: neuropsychopharmacological issues

Most children and adolescents try smoking cigarettes; up to two-thirds discontinue. What explains the one-third or more who continue smoking? What physiological, pharmacological, and other environmental factors affect the risk of developing a pattern of chronic tobacco use? How can the transition from occasional use to chronic use be slowed, if not halted? What are the safest, most effective means of intervention for those children and adolescents who develop patterns of chronic daily cigarette smoking and would like to quit? How can they be motivated to want to quit? These are just a few of the issues that might be resolved in part by further neuropsychopharmacological research, but the challenges and barriers to conducting such research on children and adolescents are substantial. The barriers may be better understood by a brief summary of what neuropsychopharmacology research involves, and a corresponding summary of the disincentives to conduct such research.

A pharmacokinetic crossover study to compare the absorption characteristics of three transdermal nicotine patches

We compared the pharmacokinetic profiles of the highest marketed doses of three different patch systems using a crossover study design. Specifically, each of the 25 subjects was assigned to receive the Pharmacia-Upjohn (McNeil) 15-mg, 16-h patch, the Novartis 21-mg, 24-h patch, and the Alza (SmithKline Beecham) 21-mg, 24-h patch. Subjects used each patch for 3 consecutive days, applying a new patch each morning. Plasma nicotine concentrations were measured 15 times during the first 24-h period and at 48, 48.5, 49.5, and 51 h following initial patch application. Measures of total nicotine absorbed (AUC), maximum plasma nicotine concentration (C(max)) and minimum plasma nicotine concentration (C(min)), were higher for the 21-mg, 24-h patches than for the 15-mg, 16-h patch during both the first day of dosing and during the modeled steady-state period (48-72 h after initial application). Within the 21-mg, 24-h patch systems, the Alza patch produced significantly higher AUC and C(max) values during acute dosing and during steady state, but there was no difference between C(min) values. The time to reach C(max) (T(max)) was fastest for the Alza patch system; the Pharmacia-Upjohn patch produced a faster T(max) than the Novartis patch. These results indicate that there are significant differences between the pharmacokinetics of the currently marketed patch systems, which may be important for effective relief of withdrawal symptoms and cigarette craving.

Tolerance to repeated nicotine administration on performance, subjective, and physiological responses in nonsmokers

RATIONALE

When administered acutely to nonsmokers, nicotine's effects on performance are inconsistent, perhaps because of suboptimal dosing or initial dysphoria that could interfere with performance.

OBJECTIVE

The purpose of this study was to determine if a range of nicotine doses administered for 8 days to nonsmokers would enhance psychomotor and cognitive abilities and to document the development of nicotine tolerance or sensitization.

METHODS

Twelve male volunteers, who reported ever smoking five cigarettes or less, participated in 8 consecutive experimental days in which they were administered four doses of nicotine polacrilex gum each day in this order: 0, 2, 4, and 8 mg. Performance, subjective, and physiological measures were assessed before and after each dose.

RESULTS

Plasma nicotine concentration ranged from 6.9 to 11.5 ng/ml following the 8 mg dose. Nicotine increased rate of responding and decreased response time on working memory (digit recall); however, accuracy was impaired. Nicotine also decreased accuracy on visual scanning and attention (two-letter search), and the 8 mg dose impaired gross motor coordination (circular lights). Tolerance did not develop to the performance impairing effects of nicotine. Nicotine produced dose-related increases in ratings of dysphoria and negative mood, including tension, anxiety, nervousness, turning of stomach, and sedation. Tolerance developed to some, but not all, of these aversive effects. Tolerance also was not observed to the increased cardiovascular measures.

CONCLUSION

Although tolerance developed to some of the aversive effects of nicotine, performance enhancement was not observed. These data do not support the hypothesis that nicotine-induced performance enhancement contributes to the reinforcing effects of tobacco use during the early stages of dependence development.

Tobacco dependence. Global public health potential for new medications development and indications

Current trends indicate that approximately 500 million of the world's existing cigarette smokers will prematurely die of causes that could be prevented by treatment of their addiction to tobacco delivered nicotine. Initial pharmacologically based treatment offerings and approaches have proven the concept that increasing the accessibility and diversity of treatment modalities helps more people quit smoking. These treatments have also shown, however, that the vast majority of smokers continues to find treatment less attractive and less accessible than cigarettes whose appeal is constantly stimulated by new formulations, marketing strategies, and implied claims of reduced risk. There appears to be considerable untapped potential public health benefit, as well as commercial opportunity, for medication developers to reach an increasing fraction of smokers who find current treatments unacceptable, inaccessible, or ineffective. The global opportunities to serve public health via medication development are growing even more rapidly as country after country recognizes the impending economic and health care problems posed by tobacco dependence and are opening their doors to treatment. Three areas of medications development offer particular promise: new forms of nicotine delivery, non-nicotine based medications, and new indications to reach those who are unable or unwilling to completely quit. This article discusses the biobehavioral rationale for medication development, the opportunities, and some of the prominent technical and regulatory challenges.

Health risks associated with cigar smoking

This article summarizes principal findings from a conference convened by the American Cancer Society in June 1998 to examine the health risks of cigar smoking. State-of-the-science reports were presented and 120 attendees (representing government and private agencies, academia, health educators, and tobacco control experts) participated in panels and summary development discussions. The following conclusions were reached by consensus: (1) rates of cigar smoking are rising among both adults and adolescents; (2) smoking cigars instead of cigarettes does not reduce the risk of nicotine addiction; (3) as the number of cigars smoked and the amount of smoke inhaled increases, the risk of death related to cigar smoking approaches that of cigarette smoking; (4) cigar smoke contains higher concentrations of toxic and carcinogenic compounds than cigarettes and is a major source of fine-particle and carbon monoxide indoor air pollution; and (5) cigar smoking is known to cause cancers of the lung and upper aerodigestive tract. JAMA. 2000;284:735-740

Mecamylamine blockade of both positive and negative effects of IV nicotine in human volunteers

The ganglionic blocker mecamylamine blocks the positive reinforcing effects of IV nicotine, but has been shown to increase cigarette smoking behavior under some conditions. The effects of mecamylamine on subjective and physiologic responses to IV nicotine were evaluated in seven healthy male volunteer cigarette smokers who provided informed consent and resided on a clinical pharmacology research unit. On four separate days, each subject was given a different oral dose of mecamylamine (placebo, 5, 10, or 20 mg). One hour later subjects received the first of four doses of IV nicotine (placebo, 0.75, 1.5, and 3.0 mg); the remaining injections were given at 1-h intervals. Both the positive effects following 0.75 mg and negative effects following 3.0 mg of nicotine were significantly reversed by mecamylamine. Thus, the mecamylamine-induced increase in smoking may be due both to competitive blockade of nicotinic receptors and nicotine's reversal of aversive effects.

Nalmefene: blockade of intravenous morphine challenge effects in opioid abusing humans

No studies have assessed the dose-effect or duration of opioid blockade in opioid abusers produced by oral nalmefene, a micro-opioid antagonist. The present study examined the profile and time course of oral nalmefene blockade of subjective and physiological effects produced by intravenous morphine. To assess these effects, seven opioid abusers received oral nalmefene (0, 50 and 100 mg) followed by intravenous morphine (0, 10 and 20 mg) challenges every 24 h for 96 h using a Latin square randomized cross-over design. The duration of blockade varied by measure and dose. Both 50 and 100 mg nalmefene blocked morphine's effects up to 48 h.

A review of tobacco smoking in adolescents: treatment implications

OBJECTIVE

To review current data on the tobacco epidemic in adolescents that impact treatment decisions.

METHOD

Epidemiological and pharmacological data, risk factors, characteristics of nicotine use in adolescents, and treatment intervention reports from the literature are discussed.

RESULTS

Of students in grades 9 to 12, 42.7% have used tobacco; 75% of teenage smokers will smoke as adults. Environmental and biological factors influence adolescent smoking, including sociodevelopmental aspects of adolescence, psychiatric history, genetic background, ethnic and gender characteristics, drug effects, and regulatory factors. Criteria for nicotine dependence are currently based on the experience with adult smokers. Overall, smoking cessation treatment for adolescents has been disappointing because of low participation, high attrition, and low quit rates.

CONCLUSION

Characterization of nicotine dependence and further assessment of the safety and efficacy of pharmacological treatment interventions in adolescents are needed given the formidable challenge of the tobacco epidemic in adolescents.

Reinforcing and subjective effects of morphine in human opioid abusers: effect of dose and alternative reinforcer

RATIONALE

Although most opioid self-administration research has been conducted with laboratory animals, such research with humans is necessary to answer questions unique to human drug-taking behavior.

OBJECTIVE

We investigated the influence of morphine dose and an alternative non-drug reinforcer on choice between morphine versus money and examined the relationship between drug-reinforced behavior and subjective euphoria.

METHODS

Five male opioid users participated in the 7-week study. During the first 5 weeks, a single dose of morphine (0, 4, 8, 16, or 32 mg/70 kg) was available each week. On Monday, subjects received an IM injection of the dose tested that week. On Tuesday, Thursday, and Friday, subjects could work for morphine or money under a second-order, progressive ratio schedule. For each primary ratio completed on the drug lever, subjects earned one-ninth of the available drug dose, and for each ratio completed on the money lever, subjects earned $1. Total amount of drug earned was administered in a single IM injection at the end of the session; money earned was credited to the subject's account.

RESULTS

As morphine dose increased, responding for drug increased in an orderly manner and responding for money decreased. During the final phase of the study, the lowest and highest doses that maintained drug responding for each subject were repeated, and the value of the alternative reinforcer was increased to $2 per ratio. This manipulation was associated with decreased drug-maintained responding at the lowest, but not the highest, reinforcing dose of morphine.

CONCLUSION

The progressive ratio, concurrent access procedure may be useful in predicting the outcome of drug abuse treatment interventions that use alternate reinforcement strategies.

Pharmacokinetics and pharmacodynamics of moist snuff in humans

INTERVENTION

Four brands of moist snuff and a non-tobacco mint snuff were tested. Subjects reported to the laboratory for five experimental sessions. After baseline measurement of dependent variables, each subject placed 2 g of one of the brands of snuff (or one Skoal Bandits pouch) between the cheek and gum for 30 minutes. The subjects remained in the experimental laboratory for an additional 60 minutes.

SUBJECTS

Ten volunteers who were daily users of smokeless tobacco.

MAIN OUTCOME MEASURES

Plasma nicotine concentration, cardiovascular effects, and subjective effects.

RESULTS

Large amounts of nicotine were delivered rapidly to the bloodstream. The amount of nicotine absorbed and the rate of absorption were related to the pH of the snuff product in aqueous suspension. Cardiovascular and subjective effects were related to the amount of nicotine absorbed.

CONCLUSIONS

Snuff products are capable of rapidly delivering high doses of nicotine, which can lead to dependence. Long-term use of snuff can lead to a number of adverse health effects including oral cancers, cardiovascular diseases, and gingival diseases. For these reasons, it is important that the public health community considers oral snuff use as a burden on public health in the same way that cigarette smoking is recognised.

Pharmacodynamic effects of new de-nicotinized cigarettes

The effects of cigarette smoking result from the delivery of nicotine, other components of smoke, and sensory stimulation. In the present study, pharmacological effects of new tobacco-derived de-nicotinized cigarettes (controls) were compared with standard cigarettes. The de-nicotinized cigarettes had the appearance, draw and taste of standard cigarettes but contained and delivered virtually no nicotine (< 0.06 mg), but delivered tar and carbon monoxide (CO). They were compared with cigarettes that delivered nicotine, CO and tar. Subjects (n = 20: 10 men, 10 women) participated in four experimental sessions in which they smoked either a standard cigarette or a de-nicotinized cigarette after either 3 or 12 h of tobacco deprivation. Heart rate, blood pressure, and EEG were recorded before, and for 1 h after, ad lib smoking. Plasma nicotine concentrations verified that de-nicotinized cigarettes did not deliver nicotine. The de-nicotinized cigarettes did not increase heart rate or activate the EEG. The subjects preferred the cigarettes that delivered nicotine compared to the de-nicotinized cigarettes. However, both types of cigarettes reduced subjective measures of tobacco craving and withdrawal. These data extend previous research that suggested the process of smoking and components of tobacco smoke other than nicotine mediate some effects of cigarette smoking. The de-nicotinized cigarettes may prove useful in evaluating effects of smoking independent of the delivery of nicotine.

Low-dose oral cocaine in humans: acquisition of discrimination and time-course of effects

Seven cocaine-abusing volunteers were trained to discriminate 50 mg oral cocaine vs placebo across 50 2-h sessions. Discriminative, subjective and autonomic effects were assessed with a procedure developed for precise characterization of their acute time-course. Subjective effects of oral cocaine began 10-15 min post-drug, peaked at 40-50 min and took up to 100 min post-drug to return nearly to baseline. Autonomic effects also began 10-15 min post-drug, peaked at 40-50 min and typically returned to baseline by 120 min post-drug; for most participants, peak heart rate and blood pressure remained within the range seen with placebo. Six out of seven participants acquired the discrimination (although this typically required 15-30 sessions, and there were some intriguing dissociations between the ability to discriminate oral cocaine from placebo and the ability to identify it as a stimulant). In most participants, oral cocaine produced increases in ratings of 'liking', 'alertness' and 'good effects', and in motor performance. Overall, the results support the sensitivity of the behavioral-testing procedure used, and show that 50 mg oral cocaine can serve as a discriminative stimulus in adult humans.

Nicotine replacement therapy

Physicians can help their patients quit smoking by recommending to all of their patients that they quit smoking with the help of nicotine replacement medications. Currently available forms of nicotine medications include gum, patch, nasal spray, and vapor inhaler. Nicotine replacement medications aid smokers in their cessation efforts by relieving the physiologic symptoms of nicotine withdrawal. Because nicotine medications do not deliver the myriad toxins and carcinogens cigarettes deliver, these medications are safe when used as directed. This article discusses the rationale behind nicotine replacement therapy in the context of tobacco dependence, the available medications, and the public health benefits of these medications.

Nicotine concentration, smoke pH and whole tobacco aqueous pH of some cigar brands and types popular in the United States

The present study examined characteristics relating to nicotine delivery of 17 cigar brands, which included small cigars, cigarillos, and large premium cigar brands. The cigars selected for analysis were intended to represent the range of cigar products currently available and in popular use. In addition to cigar characteristics previously studied such as size, nicotine content, and pH of their tobacco, the present study examined smoke pH on a puff-by-puff basis. The tobacco content of the cigars ranged in weight from 0.53 to 21.5 g. There was considerable variation in total nicotine content, which ranged from 5.9 to 335.2 mg per cigar. The aqueous pH of the tobacco from the cigars also varied widely with values ranging from 5.7 to 7.8. The smoke pH values of the smallest cigars was generally acidic, changed little across puffs, and more closely resembled the profiles previously reported for typical cigarettes. Interestingly, the smoke pH of smaller cigars and cigarillos became acidic after the first third of the cigar was consumed and then remained acidic thereafter, whereas larger cigars became acidic during the first third, then became quite alkaline during the last third. Because of wide variations in nicotine content of the tobacco across brands and of similarly wide variations in smoke pH, cigar size is not an accurate predictor of the nicotine delivery capacity of a particular cigar brand, although, in general, larger cigars are capable of providing larger total nicotine delivery with extraordinarily high delivery levels being possible from many of the large premium cigars. These results demonstrated that the popular cigars in this study contained enough nicotine for the development of dependence when smoking as few as one or two of the larger cigars per day.

Smoking after nicotine deprivation enhances cognitive performance and decreases tobacco craving in drug abusers

This study investigated the effects of nicotine deprivation and smoking on cognitive abilities and tobacco craving. Twenty smokers with histories of drug abuse completed the Questionnaire on Smoking Urges (QSU) and two cognitive tests before and after smoking two cigarettes during two 90-min sessions. After two cigarettes were smoked at Session 1, subjects were tobacco abstinent for 18 h until Session 2 the next morning. Response time on a logical reasoning test was unchanged by tobacco deprivation and was faster after smoking on Session 2. Deprivation slowed responding on a letter search test, which was reversed by smoking to pre-deprivation baseline. Tobacco deprivation increased scores on the QSU; smoking after deprivation reduced craving scores to smoking baseline levels. These results confirmed the utility of the QSU to measure changes in craving induced by tobacco deprivation and smoking. Further, the data suggest that deprivation-induced deficits and smoking-induced enhancements in performance may be specific to certain cognitive domains.

Cigarette smoking during early cocaine abstinence

Use of cocaine has been reported to increase cigarette smoking, but there are no published studies of cigarette smoking during early cocaine abstinence. The authors assessed ad libitum cigarette smoking of 12 cocaine-dependent smokers housed on a closed research ward. Last cocaine use averaged 0.6 grams 1.8 days before admission. Smoking was measured indirectly with computerized cigarette dispensers. There was no significant difference between self-reported daily number of cigarettes smoked before admission and the number of cigarettes dispensed daily for the first 7 full days after admission. These findings suggest that early cocaine abstinence does not significantly alter cigarette smoking.

Reducing the addictiveness of cigarettes. Council on Scientific Affairs, American Medical Association

OBJECTIVE

To assess the feasibility of reducing tobacco-caused disease by gradually removing nicotine from cigarettes until they would not be effective causes of nicotine addiction.

DATA SOURCES

Issues posed by such an approach, and potential solutions, were identified from analysis of literature published by the US Food and Drug Administration (FDA) in its 1996 Tobacco Rule, comments of the tobacco industry and other institutions and individuals on the rule, review of the reference lists of relevant journal articles, other government publications, and presentations made at scientific conferences.

DATA SYNTHESIS

The role of nicotine in causing and sustaining tobacco use was evaluated to project the impact of a nicotine reduction strategy on initiation and maintenance of, and relapse to, tobacco use. A range of potential concerns and barriers was addressed, including the technical feasibility of reducing cigarette nicotine content to non-addictive levels, the possibility that compensatory smoking would reduce potential health benefits, and whether such an approach would foster illicit ("black market") tobacco sales. Education, treatment, and research needs to enable a nicotine reduction strategy were also addressed. The Council on Scientific Affairs came to the following conclusions: (a) gradually eliminating nicotine from cigarettes is technically feasible; (b) a nicotine reduction strategy holds great promise in preventing adolescent tobacco addiction and assisting the millions of current cigarette smokers in their efforts to quit using tobacco products; (c) potential problems such as compensatory over-smoking of denicotinised cigarettes and black market sales could be minimised by providing alternate forms of nicotine delivery with less or little risk to health, as part of expanded access to treatment; and (d) such a strategy would need to be accompanied by relevant research and increased efforts to educate consumers and health professionals about tobacco and health.

CONCLUSIONS

The council recommends the following: (a) that cessation of tobacco use should be the goal for all tobacco users; (b) that the American Medical Association continue to support FDA authority over tobacco products, and FDA classification of nicotine as a drug and tobacco products as drug-delivery devices; (c) that research be encouraged on cigarette modifications that may result in less addicting cigarettes; (d) that the FDA require that the addictiveness of cigarettes be reduced within 5-10 years; (e) expanded surveillance to monitor trends in the use of tobacco products and other nicotine-containing products; (f) expanded access to smoking cessation treatment, and strengthening of the treatment infrastructure; and (g) more accurate labelling of tobacco products, including a more meaningful and understandable indication of nicotine content.

Effects of cigarette smoking through a partially occluded filter

The effects of a commercially available corn syrup solution that is applied to the filter end of a cigarette causing an occlusive barrier to cigarette smoke were evaluated. The manufacturer claims that the solution reduces exposure to nicotine, carbon monoxide (CO), and other constituents of tobacco smoke and may aid in smoking cessation by providing a means of gradual nicotine dose reduction. Nineteen volunteers (10 men) smoked commercial cigarettes treated with 0, 1, 2, or 3 drops of the corn syrup solution in a double-blind, crossover experiment. Increases in plasma nicotine after smoking averaged 13.3, 10.5, 9.7, and 6.0 ng/ml in the 0, 1, 2, and 3 drop conditions, respectively. In the 3 drop condition, there was a significant reduction in exhaled CO levels. Subjects reported increased difficulty in cigarette draw and a trend toward decreased strength as a function of the number of drops applied. Cardiovascular and EEG measures of smoking were not significantly affected by the application of the drops. Cigarettes treated with 0, 1, 2, or 3 drops of the solution were machine smoked using methods of the Federal Trade Commission (FTC); nicotine yields were 1.0, 1.0, 0.78, and 0.73 mg of nicotine. These results indicate that Take Out drops reduce exposure to nicotine and other constituents of tobacco smoke from a single cigarette.

Tobacco dependence treatments: review and prospectus

Cigarette smoking continues to place an enormous burden on US health systems. The treatment of tobacco-dependent persons is vital to the public health, since unmitigated smoking could lead to the development of disease and premature death in as many as 20 million current smokers in the United States. Much of this tobacco-related morbidity and mortality could be prevented by the application of existing treatments, as well as newer ones. Access to safe and effective treatments was significantly expanded in 1996, when two forms of nicotine replacement therapy (NRT), the nicotine gum and patch, became available for over-the-counter sale. Expanded access has led to significantly increased utilization and quitting. Even with these advances, however, the scope of this tobacco dependence demands that we explore alternative treatment strategies, including exposure reduction therapy (ERT) as a possible option for smokers not currently making quit attempts. In this review, we present principles to guide the development of such a therapy, and for its application, should it be proven effective.

Parkinsonian patients report blunted subjective effects of methylphenidate

Mesolimbic-mesocortical dopamine brain circuits important for psychostimulant reward in animals are developed to greater extents in humans. Brains of patients with Parkinson's disease show depletion of ventral tegmental area mesolimbic-mesocortical neurons. The authors assessed psychostimulant responses in parkinsonian patients to test whether intact dopaminergic systems are required for subjective psychostimulant effects. Responses to placebo and 15, 20, 25, and 30 mg of methylphenidate were studied in 12 parkinsonian patients and 12 neurologically intact matched controls. Physiological and subjective mood responses were recorded using the Profile of Mood States, Addiction Research Center Inventory, and Visual Analog Scale. Drug-induced changes in "good" feelings and overall drug responses were attenuated in the parkinsonian patients. These results, in conjunction with animal data, provide support for dopamine hypotheses of psychostimulant reward in humans and suggest possible bases for some of the mood disturbances found in many parkinsonian patients.

Tobacco addiction: implications for treatment and cancer prevention

The American Society of Clinical Oncology and the National Cancer Institute convened a symposium in June 1996 on tobacco addiction. Additional support for the symposium was provided by the American Medical Women's Association and the American Society of Preventive Oncology. The goals of this conference were to describe the burden and public health consequences of tobacco addiction, to describe the state of science for the treatment of nicotine dependence, and to explore new strategies to increase quit rates and to prevent the uptake of tobacco use. This article summarizes and integrates the meeting presentations on tobacco addiction and includes the topics of smoking prevalence; psychobiologic aspects of nicotine dependence; and implications for disease, treatment, and prevention. Comments on regulatory approaches and national strategies for reducing dependence are also summarized in presentations by Dr. David Kessler, former Food and Drug Administration Commissioner, and Dr. C. Everett Koop, former U.S. Surgeon General.

Inhibition of prostaglandin synthesis and effects of ethanol and pentobarbital in humans

Results from animal research suggest that pretreatment with prostaglandin synthesis inhibitors (PGSIs) may inhibit physiological and behavioral effects of moderate ethanol ingestion. We examined the effects of ethanol and pentobarbital in humans with and without pretreatment with indomethacin, a potent PGSI. Ten male subjects with histories of recreational use of ethanol and sedative/hypnotics participated in this inpatient study. The effects of indomethacin alone (0.66 mg/kg), indomethacin (0, 0.17, 0.33, 0.66 and 1.33 mg/kg) in combination with ethanol (0 and 1 g/kg) and indomethacin (0 and 0.66 mg/kg) in combination with pentobarbital (0, 1.33 and 4 mg/kg) were tested. On test days, subjects swallowed capsules containing indomethacin or placebo. One hour later, they swallowed capsules that contained pentobarbital or placebo and a large drink (500 ml) of tonic water that contained ethanol or placebo (tonic water with 2 ml of ethanol floated on top). Both ethanol and pentobarbital affected subjective ratings, performance measures and heart rate. However, indomethacin pretreatment had no influence on drug-induced changes to ethanol and pentobarbital. The results of this study illustrate the relationship between depressant drugs and human performance, but they do not support the hypothesis that inhibition of prostaglandin synthesis diminishes the effects of ethanol and pentobarbital in humans.

Review of the evidence that pH is a determinant of nicotine dosage from oral use of smokeless tobacco

OBJECTIVE

To determine whether manipulation of the pH of moist-snuff products by manufacturers could control the delivery of nicotine.

DATA SOURCES

Medline database 1966-97 using the following subject headings and keywords: nicotine, absorption, mouth mucosa, skin, hydrogen-ion concentration, smokeless tobacco, biological transport, and membranes; computer database of the tobacco bibliography maintained by the US Centers for Disease Control and Prevention's Office on Smoking and Health; bibliographies of pertinent journal articles, books, and governmental reports; personal communications with experts in nicotine pharmacology and addiction; and Brown & Williamson Tobacco Corporation documents in the Tobacco Control Archives of the University of California, San Francisco.

STUDY SELECTION

Included all relevant animal studies, in-vitro studies, nicotine replacement therapy trials, and human observational studies.

DATA SYNTHESIS

We found that the effects of pH on drug absorption have been well established in animal models for nicotine and many other acidic or basic compounds. Increased alkalinity promotes the absorption of nicotine and increases its physiological effects. Human studies, which are more limited, confirm these processes. For example, nicotine absorption is directly related to the pH when nicotine is delivered in either tobacco smoke or nicotine polacrilex gum.

CONCLUSIONS

Although other factors could influence the rate of nicotine absorption from oral tobacco, manipulating tobacco pH appears to be the primary means by which the speed of nicotine absorption is determined in moist-snuff products.

Smokeless tobacco: an addicting drug

In 1986, the Surgeon General concluded that smokeless tobacco is an addictive drug sharing many qualities with other drugs of abuse such as morphine and cocaine. Smokeless tobacco can be used to deliver psycho-active and dependence-producing levels of nicotine. Tolerance develops with repeated use, causing the user to increase nicotine dosing through increased use and/or switching to products with higher nicotine yields. Clinical signs of nicotine withdrawal develop upon cessation of use. Recent data show that smokeless tobacco products vary widely in their nicotine dosing capabilities. Low-dose products tend to be those commonly marketed toward, and used by, young people without previous smokeless tobacco experience. Many of these people develop dependence and switch to high-dose products. The present article discusses each of these qualities of smokeless tobacco in greater detail. The article also discusses qualities of smokeless tobacco that make it an effective nicotine delivery device that leads to addiction.

Evaluation of cranial electrostimulation therapy on short-term smoking cessation

The effects of cranial electrical stimulation (CES) on short-term smoking cessation were evaluated in a double-blind study of cigarette smokers who wished to stop smoking. Subjects were randomly assigned to a CES- (n = 51) or a sham-treated group (n = 50). On 5 consecutive days subjects received CES treatments (30-microA, 2-msec, 10-Hz pulsed signal) or no electrical current (sham). There were no significant differences between groups on daily cigarettes smoked, exhaled carbon monoxide, urinary cotinine levels, treatment retention, smoking urges, or total tobacco withdrawal scores, although subjects in the CES group had less cigarette craving and anxiety during the first 2 experimental days. The ineffectiveness of CES to reduce withdrawal symptoms and facilitate smoking cessation are similar to results of other clinical studies of CES in drug dependence, although positive effects of CES in animal studies have been reported.

Nicotine nasal spray and vapor inhaler: abuse liability assessment

Acute subjective and physiological effects were examined to provide information relevant to abuse liability of new nicotine delivery systems. Subjects (n = 12) were overnight-deprived smokers who received 0, 4, 8 and 16 active puffs from nicotine-containing cigarettes (0.1 mg per puff), 0, 1, 2 or 4 nasal sprays (0.5 mg nicotine per spray) and 0, 30, 60 and 120 vapor inhalations (estimated 0.013 mg nicotine per inhalation) in a within-subject single blinded design. While smokers clearly liked cigarette puffs, there was much less evidence of liking produced by either nasal spray or vapor inhaler; only modest elevations on a measure of good drug effects were observed. The novel delivery products engendered unpleasant effects of burning throat and nose, watery eyes, runny nose, coughing and sneezing that might be expected to limit abuse liability. Nicotine plasma level and heart rate increase was dose-related for cigarettes and nasal spray but not for vapor inhaler, indicating limited nicotine delivery with the latter device. Overall, results are consistent with the conclusion that the nicotine nasal spray and vapor inhaler are of substantially lower abuse liability than cigarettes in experienced cigarette smokers receiving initial exposure to these products.