Effect of acute marijuana on cardiovascular function and central nervous system pharmacokinetics of [(15)O]water: effect in occasional and chronic users

The Naturalistic Cannabis Administration Protocol (NCAP): A Proof-of-Concept Study

Lab-based studies examining the effects of cannabis administration on human behavior compromise ecological validity due to the influence of set and setting. Contextual factors of clinical settings have long been recognized as producing measurable changes in physiology, emotionality, and cognition. Among people who use drugs, these settings may be associated with higher levels of perceived stigma and stereotype threat which may meaningfully confound the effects of cannabis on outcomes of interest. Recent liberalization of cannabis regulation may allow novel and more ecologically valid approaches to assessing the acute effects of cannabis. The Naturalistic Cannabis Administration Protocol (NCAP) is a novel paradigm for the study of acute cannabis effects in an ecologically valid manner. Two independent studies demonstrated the safety and feasibility of the NCAP. Participants (N= 79; Mage = 25.44, SD = 5.67) self-administered the cannabis of their choice in their home and then (Study 1; n= 47) engaged in a leisure activity or (Study 2; n= 32) underwent cognitive assessment remotely via videoconference following cannabis administration. The NCAP was well tolerated across samples with no reported adverse events. These findings provide a rationale for the adoption of the NCAP to reduce research barriers and develop our research capabilities to fit the landscape of cannabis use today.

Effect Compartment Model for the Evaluation of Tolerance to Psychological Highness Following Smoking Marijuana

The purpose of this study is to evaluate the development of tolerance, using a population modeling approach, in recreational marijuana users after acute pulmonary administration of tetrahydrocannabinol (THC), a primary ingredient in marijuana. A total of 85 subjects in 3 separate studies smoked marijuana cigarettes (dose = 13-49 mg) under controlled conditions. Each study was designed as a randomized, crossover, double-blind, and placebo-controlled study. Up to 5 THC plasma samples and corresponding user-reported psychological highness were pooled for population modeling analyses. Age, sex, user status, and body mass index were evaluated as covariates. Population pharmacokinetic (PK) parameters were estimated in the 2-compartment PK model. PK parameters were fixed in the effect compartment model to describe the relationship between THC plasma concentration-psychological highness. The distribution rate constant in the effect compartment was estimated to be 0.988 (95%CI 0.964-1.010)/h. The population mean half-maximal effective concentration (EC₅₀ ) was 23.8 (95%CI 22.7-24.9) ng/mL. Covariate analysis revealed that user status was a significant covariate, and that chronic users appear to need higher plasma concentrations compared with occasional users to achieve a similar degree of highness. The modeling results conclude that chronic users develop tolerance to euphoria, which is the primary central nervous system effect of smoking marijuana.

Cannabis is associated with blood pressure reduction in older adults - A 24-hours ambulatory blood pressure monitoring study

BACKGROUND

Medical cannabis use is increasing rapidly in the past several years, with older adults being the fastest growing group. Nevertheless, the evidence for cardiovascular safety of cannabis use is scarce. The aim of this study was to assess the effect of cannabis on blood pressure, heart rate, and metabolic parameters in older adults with hypertension.

METHODS

We conducted a prospective study of patients aged 60 years or more with hypertension and a new prescription of cannabis. We have performed the following assessments: 24-hours ambulatory blood pressure monitoring, ECG, blood tests, and anthropometric measurements prior to the initiation of cannabis therapy and 3 months afterward. The primary outcome was change in mean 24-h blood pressure at 3 months.

RESULTS

Twenty-six patients with a mean age of 70.42 ± 5.37 years, 53.8% females completed the study. At 3 months follow-up, the mean 24-hours systolic and diastolic blood pressures were reduced by 5.0 mmHg and 4.5 mmHg, respectively (p<0.001 for both). The nadir for the blood pressure and heart rate was achieved at 3 hours post-administration. The proportion of normal dippers changed from 27.3% before treatment to 45.5% afterward. No significant changes were seen in the different metabolic parameters assessed by blood tests, anthropometric measurements, or ECG exam.

CONCLUSION

amongst older adults with hypertension, cannabis treatment for 3 months was associated with a reduction in 24-hours systolic and diastolic blood pressure values with a nadir at 3 hours after cannabis administration.

The Effects of Cannabis: Implications for the Surgical Patient

Background:

Cannabis use is increasingly prevalent. Cannabinoid receptors regulate pro-inflammatory cytokines, and compounds in marijuana exert diverse physiologic effects. As more patients use cannabis, clinicians should recognize implications of perioperative cannabis use. Although the role of cannabis use in perioperative pain control has been explored, little is known about its effect on perioperative wound healing or on hematologic, pulmonary, and cardiovascular physiology.

Methods:

We searched PubMed for English-language articles related to cannabis (ie, marijuana, cannabidiol oil, and tetrahydrocannabinol) and wound healing, cardiovascular, pulmonary, or hematologic outcomes, and surgery. Titles and abstracts were reviewed, and relevant articles were analyzed. Human, animal, and pathology studies were included. Editorials, case reports, and review articles were excluded.

Results:

In total, 2549 wound healing articles were identified; 5 human studies and 8 animal/pathology studies were included. Results were conflicting. An estimated 2900 articles related to cardiovascular effects were identified, of which 2 human studies were included, which showed tetrahydrocannabinol and marijuana caused tachycardia. A total of 142 studies regarding pulmonary effects were identified. Three human studies were included, which found no difference in respiratory complications. In total, 114 studies regarding hematologic effects were identified. The 3 included human studies found conflicting venous thromboembolism risks. The overall study quality was poor. Information about dose/duration, administration route, and follow-up was reported with variable completeness.

Conclusions:

Surgeons should consider effects of cannabis in the perioperative setting. Little is known about its perioperative effects on wound healing, or on cardiovascular, pulmonary, and hematologic physiology. Further research should elucidate the effects of administration route, dose, and timing of cannabis use among surgical patients.

Cardiovascular Effects of Medical Marijuana: A Systematic Review

Utilization of marijuana as a medicinal agent is becoming increasingly popular, and so far, 25 states have legalized it for medical purposes. However, there is emerging evidence that marijuana use can result in cardiovascular side effects, such as rhythm abnormalities, syncope/dizziness, and myocardial infarction, among others. Further, there are currently no stringent national standards or approval processes, like Food and Drug Administration (FDA) evaluation, in place to assess medical marijuana products. This review includes the largest up-to-date pooled population of patients with exposure to marijuana and reported cardiovascular effects. Although purported as benign by many seeking to advance the use of marijuana as an adjunctive medical therapy across the country, marijuana is associated with its own set of cardiovascular risks and deserves further definitive study and the same level of scrutiny we apply in research of all other types of medications. When used as a medicinal agent, marijuana should be regarded accordingly, and both clinical providers and patients must be aware of potential adverse effects associated with its use for early recognition and management.

Clinical Investigation on the Impact of Cannabis Abuse on Thyroid Hormones and Associated Psychiatric Manifestations in the Male Population

Cannabis abuse is a common public health issue and may lead to considerable adverse effects. Along with other effects, the dependence on cannabis consumption is a serious problem which has significant consequences on biochemical and clinical symptoms. This study intends to evaluate the harmful effects of the use of cannabis on thyroid hormonal levels, cardiovascular indicators, and psychotic symptoms in the included patients. This prospective multicenter study was conducted on cannabis-dependent patients with psychotic symptoms (n = 40) vs. healthy control subjects (n = 40). All participants were evaluated for psychiatric, biochemical, and cardiovascular physiological effects. Patients were selected through Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV criteria and urine samples, exclusively for the evaluation of cannabis presence. Serum thyroid stimulating hormone (TSH), T3, and T4 levels were measured using the immunoassay technique. Patients were assessed for severity of depressive, schizophrenic, and manic symptoms using international ranking scales. Various quantifiable factors were also measured for the development of tolerance by cannabis. Among the patients of cannabis abuse, 47.5% were found with schizophrenia, 20% with schizoaffective symptoms, 10% with manic symptoms, and 22.5% with both manic and psychotic symptoms. In the group-group and within-group statistical analysis, the results of thyroid hormones and cardiovascular parameters were non-significant. The psychiatric assessment has shown highly significant (p < 0.001) difference of positive, negative, general psychopathology, and total scores [through Positive and Negative Syndrome Scale (PANSS) rating scales] in patients vs. the healthy control subjects. The study revealed that cannabis abuse did not significantly alter thyroid hormones and cardiovascular parameters due to the development of tolerance. However, the cannabis abuse might have a significant contributing role in the positive, negative, and manic symptoms in different psychiatric disorders.

Regular cannabis use is associated with blunted affective, but not cardiovascular, stress responses

AIMS

To examine the potential impact of regular cannabis use on cardiovascular and subjective responses to acute stress.

DESIGN

We used a quasi-experimental design in which subjective states and cardiovascular measures were obtained during rest and in response to acute stress challenges in a sample of regular cannabis users and non-users.

PARTICIPANTS

Seventy-nine adults (forty-five cannabis users and thirty-four non-users).

MEASUREMENTS

We measured subjective states (positive affect, state stress, state anxiety, cannabis craving) and cardiovascular indicators (blood pressure, heart rate, mean arterial pressure) during baseline rest and in response to public speaking, mental arithmetic, and cold-pressor challenges. Regular cannabis use was established via self-report and was confirmed with a positive urine drug test.

FINDINGS

Regular cannabis use was associated with blunted positive affect (F = 5.67, p = .002), state stress (F = 6.05, p = .002), and state anxiety (F = 6.48, p < .001) in response to acute stress challenges. There was no evidence of an association between cannabis use and cardiovascular responses (Fs ≤ 1.54; Ps ≥ 0.21). Contrary to expectations, cannabis craving decreased in response to stress challenges (F = 8.44, p < .001).

CONCLUSION

Chronic cannabis use is associated with blunted positive and negative (stress, anxiety) affective responses to acute stress, indicating emotional dysregulation in this population.

Mechanisms for the Risk of Acute Coronary Syndrome and Arrhythmia Associated With Phytogenic and Synthetic Cannabinoid Use

Phytogenic cannabinoids from Cannabis sativa and synthetic cannabinoids are commonly used substances for their recreational and medicinal properties. There are increasing reports of cardiotoxicity in close temporal association with cannabinoid use in patients with structurally normal hearts and absence of coronary arterial disease. Associated adverse events include myocardial ischemia, conduction abnormalities, arrhythmias, and sudden death. This review details the effects of phytogenic and synthetic cannabinoids on diverse receptors based on evidence from in vitro, human, and animal studies to establish a molecular basis for these deleterious clinical effects. The synergism between endocannabinoid dysregulation, cannabinoid receptor, and noncannabinoid receptor binding, and impact on cellular ion flux and coronary microvascular circulation is delineated. Pharmacogenetic factors placing certain patients at higher risk for cardiotoxicity are also correlated with the diverse effects of cannabinoids.

Medical Cannabis for Older Patients-Treatment Protocol and Initial Results

Older adults may benefit from cannabis treatment for various symptoms such as chronic pain, sleep difficulties, and others, that are not adequately controlled with evidence-based therapies. However, currently, there is a dearth of evidence about the efficacy and safety of cannabis treatment for these patients. This article aims to present a pragmatic treatment protocol for medical cannabis in older adults. We followed consecutive patients above 65 years of age prospectively who were treated with medical cannabis from April 2017 to October 2018. The outcomes included treatment adherence, global assessment of efficacy and adverse events after six months of treatment. During the study period, 184 patients began cannabis treatment, 63.6% were female, and the mean age was 81.2 ± 7.5 years (median age-82). After six months of treatment, 58.1% were still using cannabis. Of these patients, 33.6% reported adverse events, the most common of which were dizziness (12.1%) and sleepiness and fatigue (11.2%). Of the respondents, 84.8% reported some degree of improvement in their general condition. Special caution is warranted in older adults due to polypharmacy, pharmacokinetic changes, nervous system impairment, and increased cardiovascular risk. Medical cannabis should still be considered carefully and individually for each patient after a risk-benefit analysis and followed by frequent monitoring for efficacy and adverse events.

Cardiovascular Complications of Marijuana and Related Substances: A Review

The recreational use of cannabis has sharply increased in recent years in parallel with its legalization and decriminalization in several countries. Commonly, the traditional cannabis has been replaced by potent synthetic cannabinoids and cannabimimetics in various forms. Despite overwhelming public perception of the safety of these substances, an increasing number of serious cardiovascular adverse events have been reported in temporal relation to recreational cannabis use. These have included sudden cardiac death, vascular (coronary, cerebral and peripheral) events, arrhythmias and stress cardiomyopathy among others. Many of the victims of these events are relatively young men with few if any cardiovascular risk factors. However, there are reasons to believe that older individuals and those with risk factors for or established cardiovascular disease are at even higher danger of such events following exposure to cannabis. The pathophysiological basis of these events is not fully understood and likely encompasses a complex interaction between the active ingredients (particularly the major cannabinoid, Δ9-tetrahydrocannabinol), and the endo-cannabinoid system, autonomic nervous system, as well as other receptor and non-receptor mediated pathways. Other complicating factors include opposing physiologic effects of other cannabinoids (predominantly cannabidiol), presence of regulatory proteins that act as metabolizing enzymes, binding molecules, or ligands, as well as functional polymorphisms of target receptors. Tolerance to the effects of cannabis may also develop on repeated exposures at least in part due to receptor downregulation or desensitization. Moreover, effects of cannabis may be enhanced or altered by concomitant use of other illicit drugs or medications used for treatment of established cardiovascular diseases. Regardless of these considerations, it is expected that the current cannabis epidemic would add significantly to the universal burden of cardiovascular diseases.

Marijuana Use and Cardiovascular Disease

Marijuana is currently the most used illicit substance in the world. With the current trend of decriminalization and legalization of marijuana in the US, physicians in the US will encounter more patients using marijuana recreationally over a diverse range of ages and health states. Therefore, it is relevant to review marijuana's effects on human cardiovascular physiology and disease. Compared with placebo, marijuana cigarettes cause increases in heart rate, supine systolic and diastolic blood pressures, and forearm blood flow via increased sympathetic nervous system activity. These actions increase myocardial oxygen demand to a degree that they can decrease the time to exercise-induced angina in patients with a history of stable angina. In addition, marijuana has been associated with triggering myocardial infarctions (MIs) in young male patients. Smoking marijuana has been shown to increase the risk of MI onset by a factor of 4.8 for the 60 minutes after marijuana consumption, and to increase the annual risk of MI in the daily cannabis user from 1.5% to 3% per year. Human and animal models suggest that this effect may be due to coronary arterial vasospasm. However, longitudinal studies have indicated that marijuana use may not have a significant effect on long-term mortality. While further research is required to definitively determine the impact of marijuana on cardiovascular disease, it is reasonable to recommend against recreational marijuana use, especially in individuals with a history of coronary artery disorders.

Cannabis exposure as an interactive cardiovascular risk factor and accelerant of organismal ageing: a longitudinal study

OBJECTIVES

Many reports exist of the cardiovascular toxicity of smoked cannabis but none of arterial stiffness measures or vascular age (VA). In view of its diverse toxicology, the possibility that cannabis-exposed patients may be ageing more quickly requires investigation.

DESIGN

Cross-sectional and longitudinal, observational. Prospective.

SETTING

Single primary care addiction clinic in Brisbane, Australia.

PARTICIPANTS

11 cannabis-only smokers, 504 tobacco-only smokers, 114 tobacco and cannabis smokers and 534 non-smokers.

EXCLUSIONS

known cardiovascular disease or therapy or acute exposure to alcohol, amphetamine, heroin or methadone.

INTERVENTION

Radial arterial pulse wave tonometry (AtCor, SphygmoCor, Sydney) performed opportunistically and sequentially on patients between 2006 and 2011.

MAIN OUTCOME MEASURE

Algorithmically calculated VA.

SECONDARY OUTCOMES

other central haemodynamic variables.

RESULTS

Differences between group chronological ages (CA, 30.47±0.48 to 40.36±2.44, mean±SEM) were controlled with linear regression. Between-group sex differences were controlled by single-sex analysis. Mean cannabis exposure among patients was 37.67±7.16 g-years. In regression models controlling for CA, Body Mass Index (BMI), time and inhalant group, the effect of cannabis use on VA was significant in males (p=0.0156) and females (p=0.0084). The effect size in males was 11.84%. A dose-response relationship was demonstrated with lifetime exposure (p<0.002) additional to that of tobacco and opioids. In both sexes, the effect of cannabis was robust to adjustment and was unrelated to its acute effects. Significant power interactions between cannabis exposure and the square and cube of CA were demonstrated (from p<0.002).

CONCLUSIONS

Cannabis is an interactive cardiovascular risk factor (additional to tobacco and opioids), shows a prominent dose-response effect and is robust to adjustment. Cannabis use is associated with an acceleration of the cardiovascular age, which is a powerful surrogate for the organismal-biological age. This likely underlies and bi-directionally interacts with its diverse toxicological profile and is of considerable public health and regulatory importance.

Smoked cannabis' psychomotor and neurocognitive effects in occasional and frequent smokers

Δ9-Tetrahydrocannabinol (THC), the primary psychoactive constituent in cannabis, impairs psychomotor performance, cognition and driving ability; thus, driving under the influence of cannabis is a public safety concern. We documented cannabis' psychomotor, neurocognitive, subjective and physiological effects in occasional and frequent smokers to investigate potential differences between these smokers. Fourteen frequent (≥4x/week) and 11 occasional (<2x/week) cannabis smokers entered a secure research unit ∼19 h prior to smoking one 6.8% THC cigarette. Cognitive and psychomotor performance was evaluated with the critical tracking (CTT), divided attention (DAT), n-back (working memory) and Balloon Analog Risk (BART) (risk-taking) tasks at -1.75, 1.5, 3.5, 5.5 and 22.5 h after starting smoking. GLM (General Linear Model) repeated measures ANOVA was utilized to compare scores. Occasional smokers had significantly more difficulty compensating for CTT tracking error compared with frequent smokers 1.5 h after smoking. Divided attention performance declined significantly especially in occasional smokers, with session × group effects for tracking error, hits, false alarms and reaction time. Cannabis smoking did not elicit session × group effects on the n-back or BART. Controlled cannabis smoking impaired psychomotor function, more so in occasional smokers, suggesting some tolerance to psychomotor impairment in frequent users. These data have implications for cannabis-associated impairment in driving under the influence of cannabis cases.

The coronary dilation effect of shen fu injection was mediated through NO

OBJECTIVES

Shen Fu Injection (SF), which consisted of Red ginseng extraction injection (RG) and prepared aconite extraction injection (RA), is a traditional Chinese medicine mainly used for various cardiac diseases. This study is to analyse SF's effects on cardiac performance and coronary circulation. And the coronary dilating effect and mechanism of the above three injections were also explored.

METHODS

Mature male guinea pigs were used as our animal model. We employed two types of perfusion methods (constant pressure and constant flow) in vitro, using Langendorff heart preparations to observe the cardiac function and coronary response to SF (1/200). The coronary dilation effects of the above three injections (1/800, 1/400 and 1/200) were recorded at basal coronary resting tone and when coronary vessels were pre-contracted with a thromboxane A2 analogue (U46619), in the presence or the absence of the inhibitor of nitric oxide synthesis (L-NAME, 10-4 M), the blocker of Ca2+-activated potassium channel(TEA, 10-3 M), or the blocker of adenosine triphosphate (ATP)-sensitive potassium channel (glybenclamide) (10-5 M).

RESULTS

When perfused with constant pressure, SF significantly increased coronary flow, left ventricular developed pressure (LVDP) and the rate-pressure product (RPP). When perfused with constant flow, SF produced a significant reduction in the coronary perfusion pressure (CPP), LVDP and RPP. The coronary vasodilatation response of the above three injections can be reduced by L-NAME but was unaffected by TEA or glybenclamide when coronary vessels were pre-contracted with U46619 but not at resting tone. SF, RG and RA can all up-regulate eNOS expression in the human umbilical vein cells (EA.hy926).

CONCLUSION

We demonstrated that SF does not contribute to the inotropic change of myocardium whose improvement is due to alternation of coronary flow. The coronary dilation effect of SF was mediated through RG and RA, via promoting NO release.

Oroxylin a, but not vasopressin, ameliorates cardiac dysfunction of endotoxemic rats

The mortality in septic patients with myocardial dysfunction is higher than those without it. Beneficial effects of flavonoid oroxylin A (Oro-A) on endotoxemic hearts were evaluated and compared with that of arginine vasopressin (AVP) which is used to reverse hypotension in septic patients. Endotoxemia in rats was induced by one-injection of lipopolysaccharides (LPS, 10 mg/kg, i.p.), and hearts were isolated 5-hrs or 16-hrs later. Isolated hearts with constant-pressure or constant-flow mode were examined by Langendorff technique. Rate and force of contractions of isolated atrial and ventricular strips were examined by tissue myography. Isolated endotoxemic hearts were characterized by decreased or increased coronary flow (CF) in LPS-treated-for-5hr and LPS-treated-for-16-hr groups, respectively, with decreased inotropy in both groups. Oro-A-perfusion ameliorated while AVP-perfusion worsened the decreased CF and inotropy in both preparations. Oro-A and AVP, however, did not affect diminished force or rate of contraction of atrial and ventricular strips of endotoxemic hearts. Oro-A-induced CF increase was not affected following coronary endothelium-denudation with saponin. These results suggest that Oro-A ameliorates LPS-depressed cardiac functions by increasing CF, leading to positive inotropy. In contrast, AVP aggravates cardiac dysfunction by decreasing CF. Oro-A is a potentially useful candidate for treating endotoxemia complicated with myocardial dysfunction.

Tolerance to effects of high-dose oral δ9-tetrahydrocannabinol and plasma cannabinoid concentrations in male daily cannabis smokers

Oral cannabinoids are taken for medicinal or recreational purposes, yet little is known about tolerance to their effects after high-dose extended exposure. The development of tolerance to effects of around-the-clock oral synthetic Δ9-tetrahydrocannabinol (THC) (20 mg every 3.5-6 h) was evaluated in 13 healthy male daily cannabis smokers residing on a secure research unit: 40 mg on Day 1; 100 mg on Days 2-4; 120 mg on Days 5-6. Systolic and diastolic blood pressure (BP), heart rate, and symptoms of subjective intoxication (100 mm visual-analogue scales, VAS) were assessed the morning of Day 1 (before any oral THC), and on Days 2, 4 and 6, every 30 min for 3 h after the first morning THC dose. Morning subjective intoxication ratings increased from Days 1 to 2, and then declined on Days 4 and 6. The morning THC dose increased intoxication ratings on Day 2, but had less effect on Days 4 and 6, a pattern consistent with tolerance. THC lowered BP and increased heart rate over the six days. Plasma THC and 11-OH-THC concentrations increased significantly over the first five days of dosing. Six days of around-the-clock, oral THC produced tolerance to subjective intoxication, but not to cardiovascular effects.

Lifetime substance misuse and 5-year incidence rates of emergent health problems among middle-aged adults

Understanding the impact of prior substance misuse on emergent health problems is important to the implementation of effective preventive care. This study examined the 5-year incidence rates using a sample of middle-aged adult adoptees (N = 309, mean(age) = 44.32, standard deviation(age) = 7.28). Subjects reported on health problems at two waves of study. DSM-IV diagnoses of substance misuse were obtained using a semi-structured diagnostic interview. Finally, health services utilization and perceived health status were collected. Lifetime diagnoses of marijuana and other non-marijuana substance misuse significantly predicted new occurrences of cardiovascular and metabolic disease. Alcohol misuse predicted earlier onset of cardiovascular disease among men. Marijuana and other non-marijuana drugs predicted earlier onset of cardiovascular disease for men and women. Finally, marijuana and other non-marijuana drugs predicted earlier onset of metabolic disease among men. Substance misuse did not predict health services utilization despite higher rates of disease. These findings emphasize the need to assess lifetime substance misuse when evaluating health risks associated with use.

Heavy marijuana users show increased serum apolipoprotein C-III levels: evidence from proteomic analyses

Marijuana (MJ) is the most commonly used illicit drug in the United States. Its abuse is associated with cognitive dysfunctions and increased resistance to blood flow in the cerebral vasculature. In addition, MJ abuse is associated with increased risks of potentially serious cardiovascular disorders. In the present study, we used the protein chip platform based on surface-enhanced laser desorption/ionization time-of-flight mass spectroscopy (SELDI-TOF-MS) to test the possibility that MJ abuse might be associated with changes in serum protein levels. Indeed, MJ users showed significant increases in three protein peaks, which were identified as three isoforms of apolipoprotein (apo) C-III. Immunoprecipitation using an apoC-III antibody also validated the identification of the proteins. Marijuana-induced increases in apoC-III levels might occur through chronic stimulation of hepatic cannabinoid receptors (CB1 and/or CB2) by its active ingredient, Delta(9)tetrahydrocannibol (THC). Thus, chronic MJ abuse might cause increased transcription and/or translation of apoC-III in the liver with corresponding changes reflected in the plasma of these patients. In any case, because apoC-III is a cardiovascular risk factor, the increased levels observed in MJ users might explain, in part, the cardiac and cerebral abnormalities reported in these patients.

Intermittent marijuana use is associated with improved retention in naltrexone treatment for opiate-dependence

Naltrexone is a theoretically promising alternative to agonist substitution treatment for opioid dependence, but its effectiveness has been severely limited by poor adherence. This study examined, in an independent sample, a previously observed association between moderate cannabis use and improved retention in naltrexone treatment. Opioid dependent patients (N = 63), admitted for inpatient detoxification and induction onto oral naltrexone, and randomized into a six-month trial of intensive behavioral therapy (Behavioral Naltrexone Therapy) versus a control behavioral therapy (Compliance Enhancement), were classified into three levels of cannabis use during treatment based on biweekly urine toxicology: abstinent (0% cannabis positive urine samples); intermittent use (1% to 79% cannabis positive samples); and consistent use (80% or greater cannabis positive samples). Intermittent cannabis users showed superior retention in naltrexone treatment (median days retained = 133; mean = 112.8, SE = 17.5), compared to abstinent (median = 35; mean = 47.3, SE = 9.2) or consistent users (median = 35; mean = 68.3, SE = 14.1) (log rank = 12.2, df = 2, p = .002). The effect remained significant in a Cox model after adjustment for baseline level of heroin use and during treatment level of cocaine use. Intermittent cannabis use was also associated with greater adherence to naltrexone pill-taking. Treatment interacted with cannabis use level, such that intensive behavioral therapy appeared to moderate the adverse prognosis in the consistent cannabis use group. The association between moderate cannabis use and improved retention on naltrexone treatment was replicated. Experimental studies are needed to directly test the hypothesis that cannabinoid agonists exert a beneficial pharmacological effect on naltrexone maintenance and to understand the mechanism.

Tolerability and effects of oral Delta9-tetrahydrocannabinol in older adolescents with marijuana use disorders

OBJECTIVE

The tolerability and effects of oral Delta9-tetrahydrocannabinol (THC) have been previously investigated in adult marijuana abusers. However, no studies have included adolescent participants. This double-blind laboratory study investigated the tolerability and effects of oral THC in a group of older adolescents with marijuana use disorders.

METHODS

Eight participants (ages 16-21 years), smoking an average of 5.2 days/week and 2.5 "joints"/day, completed this four-session study, during which they received one of four oral THC doses (0, 2.5, 5, 10 mg) each session. Administration of oral THC doses was counterbalanced across participants. During each session, participants completed the Digit-Symbol Substitution Task (DSST) and subjective-effect ratings at baseline and 1, 2, and 3 h after oral THC administration.

RESULTS

Oral THC (5 mg and 10 mg) increased several "positive" subjective-effect ratings (e.g., "Good Drug Effect"), while producing no significant effects on cardiovascular measures, DSST performance, or "negative" subjective-effect ratings.

CONCLUSIONS

These results indicate that oral THC was well tolerated and suggest further study of this medication in adolescent marijuana abusers.