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Biomedical subjects

Jack E Henningfield

Publications and source records attributed to Jack E Henningfield.

At least 19 recordsLinked to original sources
PubMed2026

Safety and Tolerability of Single and Multiple Daily Oral Doses of Dried Kratom Leaf Powder in a Randomized Trial in Healthy Volunteers.

BACKGROUND: Kratom use is rising, increasing the need for safety and tolerability studies of high-quality and well-characterized kratom products in humans. Kratom's risk-benefit ratio, recommended dose, treatment-emergent adverse events (TEAEs), abuse potential, and withdrawal require evaluation. Thus, the safety and tolerability of 4 escalating single and 15 daily dried kratom leaf powder doses in human volunteers were evaluated over 47 days in the largest controlled kratom-administration study to date. METHODS: A randomized, between-subject, double-blind, placebo-controlled, dose-escalation study of MitraLeaf kratom powder after single doses (SD), during 15 daily doses (multiple doses; MD), and a 23-day follow-up was conducted in 116 volunteers (49 MitraLeaf and 67 placebo). Twelve participants each received a SD of either 6.65, 13.3, 26.6, or 53.2 mg (n = 13) mitragynine in 500, 1000, 2000, or 4000 mg of MitraLeaf, respectively, with a 10-day follow-up. The same participants received 15 daily doses at the same concentration of SD mitragynine received, with a 27-day follow-up period. Inclusion criteria were nonsmoking healthy males and females who never used kratom or had not used kratom for ≥12 months, 18-55 years old, and BMI ≥18.5 and ≤29.9 kg/m 2 . Participants were excluded if they had known CYP3A4, CYP2D6, or CYP1A2 genetic polymorphisms. RESULTS: No serious adverse events or deaths were reported. TEAEs after SD or MD generally increased as the dose increased. Dizziness, nausea, and feeling of relaxation were the most commonly reported TEAEs after SD, and headache, feeling hot, increased alanine aminotransferase level, and nausea were most common after MD. CONCLUSIONS: This SD and first MD controlled study shows that Mitragyna speciosa -derived MitraLeaf kratom powder was safe and well tolerated at the dose ranges tested, with no evidence of meaningful abuse potential or withdrawal.

Humans↗
PubMed2006

Serotonergic responsiveness in human cocaine users.

BACKGROUND: Animal experiments show that repeated cocaine injections induce changes in brain serotonin (5-hydroxytryptamine, or 5-HT) function which can be detected by altered neuroendocrine responsiveness to serotonergic drug challenge. Studies of human cocaine users given a serotonergic challenge have produced inconsistent results. METHODS: Hormone responses evoked by the 5-HT releaser D,L-fenfluramine (FEN) were examined in eight human cocaine users who resided on a closed research ward. FEN (60 mg oral) was given after a 7-day cocaine-free period and 3 days after a 5-day period of daily double-blind administration of intranasal cocaine (96 mg) and active placebo (4 mg cocaine). Plasma cortisol and prolactin levels were measured after FEN challenges, and after cocaine and placebo administration. RESULTS: Cocaine significantly elevated plasma cortisol levels to a similar degree on the first and fifth days of administration, but did not alter prolactin levels on either day. The first FEN challenge significantly increased plasma prolactin and cortisol, whereas the second challenge increased only prolactin. CONCLUSIONS: Intranasal cocaine increases plasma cortisol without affecting prolactin, with no evidence for tolerance. The reduction in FEN-induced cortisol secretion after cocaine exposure suggests that deficits in 5-HT transmission during early cocaine abstinence might contribute to the maintenance of drug dependence.

Adult↗
PubMed2006

Impact of formulation on the abuse liability, safety and regulation of medications: the expert panel report.

A scientific meeting was held in April 2005 to consider how the formulation of medications might impact on their potential for abuse. The background papers prepared for this meeting, as well as abstracts of volunteered presentations, are published in this supplemental issue of Drug and Alcohol Dependence. This paper is the Expert Panel Report summarizing the discussions held following the formal presentations and including the suggested recommendations for additional research that emerged from these discussions. There was overwhelming consensus that formulation does play a role in prescription drug abuse, i.e., a formulation of an abused substance can be developed that will decrease its abuse potential, and several examples were cited. Nevertheless, it is imperative that new formulations have similar efficacy and in no way compromise medication access to doctors and patients. However, there was also consensus that a great deal of research and discussion was needed to fully implement a program of risk management through reformulation of existing products or tailoring the formulation of new products to retain clinical efficacy and safety while minimizing potential for abuse. Those who need to take part in this discussion include scientific groups, pharmaceutical companies, as well as governmental and regulatory agencies. The areas where more research is needed include development of standards for assessing tamper-resistance, improved animal models that can address formulation-related variables (e.g., onset, duration), the redesign of human laboratory studies providing appropriate models for comparing formulations, and improved post-marketing surveillance. Finally, knowledge and experience are needed to translate scientific work into a predictable, transparent and reliable regulatory process.

Chemistry, Pharmaceutical↗
PubMed2006

Nicotine psychopharmacology research contributions to United States and global tobacco regulation: a look back and a look forward.

Nicotine has a long and storied history in physiology and pharmacology. Historically, it has been used as a tool to explore the nervous system, studied for its role in tobacco use, and more recently examined for its diverse potential medicinal uses. Psychopharmacology research has been pivotal in the science foundation for nicotine and tobacco product regulation.

Animals↗
PubMed2006

Tobacco industry litigation position on addiction: continued dependence on past views.

This paper reviews the tobacco industry's litigation strategy for addressing the addiction issue through trial testimony by its experts, and opening and closing statements by its lawyers. Despite the fact that several companies now claim to accept, in varying degrees, the conclusions of the Surgeon General concerning tobacco addiction, the tobacco industry litigation strategy pertaining to addiction is essentially unchanged since that of the early 1980s when the issue emerged as crucial. The industry uses its experts and the process of cross-examination of plaintiff's experts to imply that the addictiveness of tobacco and nicotine are more comparable to substances such as caffeine, chocolate, and even milk, than to heroin, cocaine and alcohol. Furthermore, the tobacco industry contends that the definition of addiction has now become so broadened as to include carrots and caffeine and hence that any concurrence that smoking is addictive, does not imply that cigarettes are addictive to the standards that drugs such as heroin and cocaine are addictive. Finally, the industry has continuously asserted that tobacco users assumed the risks of tobacco since they understood that quitting could be difficult when they began to use, and moreover, that the main barrier to cessation is lack of desire or motivation to quit and not physical addiction. These positions have been maintained through the 2004-2005 US Government litigation that was ongoing as the time of this writing.

Biomedical Research↗
PubMed2005

Effect of rate of administration on subjective and physiological effects of intravenous cocaine in humans.

The rate hypothesis of psychoactive drug action holds that the faster a drug reaches the brain and starts to act, the greater its reinforcing effects and abuse liability. A previous human study using a single cocaine dose confirmed the rate hypothesis for subjective responses, but found no rate effect on cardiovascular responses. We evaluated the rate hypothesis in 17 experienced cocaine users (7 [all men] provided complete data; 6 participated in only 1-2 sessions) by administering IV cocaine at each of three doses (10, 25, 50 mg) and injection durations (10, 30, 60 s) in a double-blind, placebo-controlled, escalating dose design. Heart rate, blood pressure, and positive (e.g., rush, high) and negative (e.g., feel bad, anxious) subjective effects (100-mm visual analogue scales) were measured for 1h after dosing. Peak change from baseline, time to peak, and area under the time-response curve were evaluated with repeated measures mixed linear regression analyses, allowing use of data from all sessions for all subjects, including non-completers. Both dose (mg) and infusion rate (mg/s) significantly influenced most subjective and cardiovascular variables. Analysis of the interaction suggested that dose had a stronger impact than rate. Rate had a stronger influence on positive subjective effects than on negative subjective effects or cardiovascular variables. These findings provide support for the rate hypothesis as it applies to both subjective and cardiovascular effects of IV cocaine administration in humans.

Adult↗
PubMed2005

Human cocaine-seeking behavior and its control by drug-associated stimuli in the laboratory.

Second-order schedules of drug self-administration were developed to incorporate the effects of drug-related environmental stimuli into an animal model of drug abuse, making it more similar to human situations. Ironically, little is known about how human subjects behave under these schedules. In this study, human volunteers with a history of cocaine use worked on a second-order schedule in which every 100th lever response produced an auditory-visual brief stimulus (2 s). The first stimulus produced after 1 h was extended to 10 s and paired with an intravenous injection of cocaine (25 mg). Up to three injections were allowed per session. In different phases of the experiment, presentation of the brief stimulus was discontinued and/or saline solution (placebo) was injected instead of cocaine. Injections of cocaine were found to maintain responding even when the brief stimulus was not presented. Placebo injections alone did not maintain responding. In contrast, the brief stimulus maintained high levels of responding under placebo conditions, even though self-reports indicated that subjects could clearly discriminate that they were not receiving cocaine. These results demonstrate that drug-related environmental stimuli can maintain persistent drug seeking during periods of drug unavailability. As this procedure directly measures the effects of stimuli on drug seeking, it may provide a valuable complement to indirect measures, such as self-reports of craving, that are often used with human subjects. The similarity of the response patterns in humans and animals also supports the use of second-order schedules in animals as a valid model of human drug seeking.

Adult↗
PubMed2005

Relationship between plasma and oral fluid nicotine concentrations in humans: a pilot study.

The relationship between plasma and oral fluid concentrations of nicotine after infusion at varying times was investigated. Five healthy human volunteers were administered 0, 0.75, and 1.5 mg nicotine as 0.5-, 1.0-, 2.5-, and 5-minute infusions. Blood and oral fluid were collected before drug administration and for 4 hours thereafter. Nicotine concentrations were determined by HPLC using a limit of quantification of 1 ng/mL. Plasma nicotine concentrations were dose related. Peak plasma concentrations (mean+/-SD) at the 4 infusion times were 14.1+/-5.5, 11.8+/-5.3, 12.8+/-1.9, and 11.5+/-4.0 ng/mL (N=5) after the 0.75-mg dose and 26.3+/-11.7, 19.3+/-12.8, 24.54+/-10.4, and 19.02+/-6.5 ng/mL after the 1.5-mg dose. In general, the highest peak concentration occurred at the shortest infusion time at each dose. Peak nicotine oral fluid concentrations (mean+/-SD) at the 4 infusion times of 22.4+/-29.1, 22.64+/-29.9, 19.1+/-13.5, and 49.1+/-31.7 ng/mL (n=5) after the low dose and 35.8+/-21.1, 26.0+/-7.7, 33.3+/-28.8, and 104.0+/-68.9 ng/mL, after the 1.5 mg dose. The highest oral fluid concentration of nicotine occurred at the longest infusion time at each dose. Oral fluid/plasma were >1 for up to 60 minutes after the low dose and 120 minutes after the high dose. There was no correlation between plasma and oral fluid nicotine concentrations.

Adult↗
PubMed2005

Nicotine delivery systems.

Over the past 20 years, medicinal nicotine has been used to aid smoking cessation, and has led to a significant increase in the number of smokers who successfully quit. This review describes currently available medicinal nicotine products, which include nicotine patch, gum, lozenge, nasal spray, inhaler and sublingual tablet, including their pharmacokinetics and recommended dosing. New developments in nicotine delivery that could further increase cessation rates include high-dose patches, rapid release gum, combined patch and acute forms, and several novel channels for nicotine delivery, such as nicotine drink, straw, lollipop and a pulmonary inhaler. New applications of existing and novel medicinal nicotine products may include relapse prevention, nicotine maintenance, temporary withdrawal management, reduced smoking and gradual quitting.

Area Under Curve↗
PubMed2004

Nicotine serves as an effective reinforcer of intravenous drug-taking behavior in human cigarette smokers.

RATIONALE: Although numerous studies have documented that nicotine can function as an effective reinforcer of intravenous self-administration behavior in animals, it has not been clearly shown to maintain intravenous self-administration behavior above vehicle placebo levels in humans. OBJECTIVES: To compare the reinforcing effectiveness of nicotine versus saline placebo in human research volunteers responding under fixed-ratio (FR) schedules of intravenous drug self-administration while systematically increasing response requirements. METHODS: Eight male cigarette smokers resided in an inpatient research unit. During 3-h sessions, intravenous injections of nicotine and saline were available concurrently and were contingent on responding (pulling a lever). Nicotine dose (0.75, 1.5, 3.0 mg/injection), time out (TO) value after each injection (1-20 min) and FR response requirement (10-1600) were varied in different subjects over consecutive sessions. RESULTS: Number of nicotine injections/session significantly decreased as dose/injection increased and the number of self-administered nicotine injections was significantly greater than the number of self-administered saline injections across conditions. When FR value was progressively increased over sessions, response rates for nicotine, but not saline, injections increased, with maximal rates at the highest FR values. Rates of responding and injections/session were markedly and significantly higher for nicotine than for saline at FR values of 200 and above. Subjects rated effects of nicotine as both significantly more positive and more negative than saline placebo, with positive ratings significantly higher than negative ratings. CONCLUSIONS: Nicotine functioned as a prototypic drug of abuse, serving as an effective reinforcer of intravenous drug-taking behavior in human cigarette smokers. Subjects adjusted their responding to response requirements in a way that maintained relatively constant levels of nicotine injections per session.

Adult↗
PubMed2004

Assessing internal tobacco industry knowledge of the neurobiology of tobacco dependence.

The recent availability of internal tobacco industry documents provides a significant resource for evaluating industry understanding of the pharmacological, psychosocial, and behavioral mechanisms underlying tobacco dependence. In this study, we catalog the range of efforts undertaken by tobacco manufacturers seeking knowledge of these mechanisms. Some areas of industry research, such as cellular and molecular studies of nicotine and its effects, are widely available in the open literature. Of greater interest are internal research projects that have demonstrated direct influence on product development. These include studies of smoker psychology and behavior, evoked-response studies of tobacco-delivered nicotine, the effects of sensory perception, dose-related effects, and the development of nicotine analogs and synergists. Our findings suggest extensive industry knowledge of mechanisms that determine smoker perception and behavior, and application of this knowledge in product development, including control of sensory response, uptake of nicotine, and product effects. Independent research recently has begun to consider the contributions of tobacco product ingredients and design factors to the determination of risk, severity, and prevalence of addiction. However, the application of these findings to cessation and treatment efforts is still quite limited. We conclude that clinical research would greatly benefit from further examination of the decades of knowledge accumulated by tobacco manufacturers.

Brain↗