5HT-2C agonist lorcaserin decreases cannabis self-administration in daily cannabis smokers.

There are no FDA-approved treatments for cannabis use disorder (CUD). Preclinical research has shown that the 5HT-2C agonist lorcaserin attenuates cue-induced reinstatement of THC seeking and self-administration. The goal of this placebo-controlled, counterbalanced, within-subject human laboratory study was to examine lorcaserin's effects on cannabis intoxication and self-administration. Lorcaserin (10 mg BID) was administered during one of two 13-day inpatient phases and placebo during the other; each phase was separated by ≥7 days of washout. Inpatient phases comprised (1) standardized cannabis administration (7.0% THC) at no financial cost (intoxication), counterbalanced with (2) the option to self-administer cannabis following either 0 or 3 days of abstinence. Cognitive task performance, food intake, subjective ratings of drug effects, objective/subjective sleep measures, and tobacco cigarette use were also assessed. Fifteen normal-weight, daily cannabis users (4F, 11M) not seeking treatment for CUD completed the study. Lorcaserin significantly reduced cannabis self-administration following 0 and 3 days of cannabis abstinence and also reduced craving for cannabis during abstinence. Lorcaserin produced small but significant increases in positive cannabis ratings and body weight relative to placebo. Lorcaserin also reduced tobacco cigarette smoking on days of cannabis administration relative to placebo. During abstinence, subjective but not objective measures of sleep quality worsened during lorcaserin maintenance. Overall, lorcaserin's ability to decrease drug taking and cannabis craving in nontreatment-seeking cannabis users supports further investigation of 5HT-2C agonists as potential pharmacotherapies for CUD.

Quetiapine treatment for cannabis use disorder.

BACKROUND: Pharmacotherapy for cannabis use disorder (CUD) is an important unmet public health need. METHODS: In a 12-week randomized double-blind placebo-controlled trial, the efficacy of quetiapine (300 mg nightly) for the treatment of CUD was tested in 130 outpatients. Weekly cannabis use was categorized into three groups: heavy use (5-7 days), moderate use (2-4 days) and light use (0-1 days). RESULTS: At baseline both groups were considered heavy users (using days per week: median = 7.0; interquartile range (IQR): 6.5-7.0; daily dollar value: median = $121.4; IQR: 73.8-206.3). The week-by-treatment interaction was marginally significant (χ2(2) = 5.56, P = .06). With each week, the odds of moderate compared to heavy use significantly increased in the quetiapine group (OR=1.17, P < .0001), but not significantly in the placebo group (OR=1.05, P = .16). The odds of light versus heavy use did not significantly differ over time (P = .12). Treatment was also associated with reduced cannabis withdrawal symptoms by 10.4% each week (95% CI: 8.9-11.8). No serious adverse events occurred during the study and no evidence of development of a movement disorder was detected. Adverse effects were not significantly different between the quetiapine and placebo treatment arms. CONCLUSIONS: The use of quetiapine to treat CUD was associated with an increased likelihood of heavy frequency use transitioning to moderate use, but not light use. The clinical significance of reductions in cannabis use, short of abstinence warrants further study.

Nicotine patch for cannabis withdrawal symptom relief: a randomized controlled trial.

RATIONALE: Given that tetrahydrocannabinol (THC) and nicotine have similar effects on negative affect (NA), we hypothesized that a 7-mg nicotine patch (NP) would reduce NA-related cannabis (CAN) withdrawal symptoms in cannabis-dependent (CD) individuals who were not nicotine dependent. OBJECTIVE: We sought to determine whether NP reduces NA across 15 days of CAN abstinence in two groups: non-tobacco smokers (NTS) and light tobacco smokers (LTS). METHODS: CD participants (N = 127; aged 18-35) who used CAN at least 5 times/week for the past 12 + months were randomized to (1) NP or (2) a placebo patch (PP) and received $300 for sustained biochemically verified CAN abstinence. Of those randomly assigned, 52 of 63 NP, and 56 of 64 PP maintained biochemically verified CAN abstinence and 51 NP and 50 PP participants complied with all aspects of the study. Affect and other withdrawal symptoms were measured every 48 h across 15 days of CAN abstinence. RESULTS: After controlling for age, tobacco use, baseline THC concentration, and baseline measurements of the dependent variable, NP reduced NA symptoms across the 15-day treatment relative to PP. Differences in NA and CAN withdrawal symptoms were not moderated by tobacco user status. CONCLUSIONS: The findings provide the first evidence that NP may be able to attenuate NA-related withdrawal symptoms in individuals with cannabis use disorder who are not heavy users of tobacco or nicotine. CLINICAL TRIALS REGISTRY: NCT01400243 http://www.clinicaltrials.gov.

Cannabis and Alcohol Co-Use in a Smoking Cessation Pharmacotherapy Trial for Adolescents and Emerging Adults.

INTRODUCTION: The co-use of cannabis and alcohol among tobacco-using youth is common. Alcohol co-use is associated with worse tobacco cessation outcomes, but results are mixed regarding the impact of cannabis on tobacco outcomes and if co-use leads to increased use of non-treated substances. This secondary analysis from a youth smoking cessation trial aimed to (1) evaluate the impact of cannabis or alcohol co-use on smoking cessation, (2) examine changes in co-use during the trial, and (3) explore secondary effects of varenicline on co-use. METHODS: The parent study was a 12-week, randomized clinical trial of varenicline for smoking cessation among youth (ages 14-21, N = 157; Mage = 19, 40% female; 76% White). Daily cigarette, cannabis, and alcohol use data were collected via daily diaries during treatment and Timeline Follow-back for 14 weeks post-treatment. RESULTS: Baseline cannabis co-users (68%) had double the odds of continued cigarette smoking throughout the trial compared with noncannabis users, which was pronounced in males and frequent cannabis users. Continued smoking during treatment was associated with higher probability of concurrent cannabis use. Baseline alcohol co-users (80%) did not have worse smoking outcomes compared with nonalcohol users, but continued smoking was associated with higher probability of concurrent drinking. Varenicline did not affect co-use. CONCLUSIONS: Inconsistent with prior literature, results showed that alcohol co-users did not differ in smoking cessation, whereas cannabis co-users had poorer cessation outcomes. Youth tobacco treatment would benefit from added focus on substance co-use, particularly cannabis, but may need to be tailored appropriately to promote cessation. IMPLICATIONS: Among youth cigarette smokers enrolled in a pharmacotherapy evaluation clinical trial, alcohol and/or cannabis co-use was prevalent. The co-use of cannabis affected smoking cessation outcomes, but more so for males and frequent cannabis users, whereas alcohol co-use did not affect smoking cessation. Reductions in smoking were accompanied by concurrent reductions in alcohol or cannabis use. Substance co-use does not appear to affect all youth smokers in the same manner and treatment strategies may need to be tailored appropriately for those with lower odds of smoking cessation.

Antipsychotic treatment failure in patients with psychosis and co-morbid cannabis use: A systematic review.

Whilst the effects of cannabis preceding psychosis onset are well established, an effect post-onset is less clear. Emerging evidence suggests that cannabis use is associated with increased relapse outcomes possibly because of determinants, antipsychotic treatment failure and medication adherence, that are not mutually exclusive. Due to the paucity of literature on antipsychotic treatment failure an association with cannabis remains conjectural. This review sought to summarise current evidence regarding the effect of cannabis use on antipsychotic treatment failure among users and non-users with psychosis. Ovid databases (Embase, Journals@Ovid Full Text, OvidMEDLINE® In-Process and Other Non-Indexed Citations and PsycINFO) were searched to identify relevant articles. Seven articles met eligibility criteria. Cannabis use was associated with the following deleterious outcomes increased: odds of non-remission, prescription of unique antipsychotic medications, cumulative prescription of Clozapine and poor treatment trajectories. One study reported similar life-time, but lower past-year, rates of cannabis use in those prescribed Clozapine. Another study reported differences between groups for chlorpromazine equivalent doses for long-term Olanzapine prescription. Improved methodologies are warranted due to a lack of well-designed prospective studies and heterogeneity of key variables. There remains, despite research paucity, the need to encourage early cannabis cessation and higher-quality research to inform clinical practice.

Influence of tiagabine maintenance on cannabis effects and related behaviors in daily cannabis users.

No medications are approved for cannabis use disorder (CUD). Gamma-aminobutyric acid (GABA) reuptake is modulated by cannabinoid (CB) receptor agonists, and there are shared effects between CB agonists and the GABA reuptake inhibitor tiagabine. This overlapping neuropharmacology suggested that tiagabine might be useful for CUD. The study determined the ability of tiagabine maintenance to reduce cannabis self-administration using a placebo-controlled, double-blind, counterbalanced, within-subjects design. Nontreatment-seeking daily cannabis users (N = 12; 3 female, 9 male) completed two 12-day outpatient maintenance phases (0 or 12 mg of tiagabine/day). Each phase consisted of a safety session, 7 maintenance days, and 4 experimental sessions. During experimental sessions, maintenance continued and participants completed two 2-day blocks of sampling and self-administration sessions to determine the reinforcing effects of smoked cannabis (0% and 5.9% Δ9-tetrahydrocannabinol). Naturalistic cannabis use, the subjective, performance and physiological response to cannabis, as well as side effects, sleep quality, craving, other self-reported substance use, and observer ratings were also measured. Cannabis functioned as a reinforcer and produced prototypical effects (e.g., increased heart rate and ratings of "high"), but tiagabine generally did not impact the effects of cannabis, or alter naturalistic use. Furthermore, tiagabine produced small, but significant, increases on 2 subscales of a Marijuana Craving Questionnaire, and reductions in both the amount of time slept in the past 24 hr and ratings of positive mood upon awakening. These human laboratory results from a sample of nontreatment-seeking cannabis users do not support the potential efficacy of 12 mg of tiagabine as a stand-alone pharmacotherapy for CUD. (PsycINFO Database Record

The effect of high-dose dronabinol (oral THC) maintenance on cannabis self-administration.

BACKGROUND: There is a clear need for advancing the treatment of cannabis use disorders. Prior research has demonstrated that dronabinol (oral THC) can dose-dependently suppress cannabis withdrawal and reduce the acute effects of smoked cannabis. The present study was conducted to evaluate whether high-dose dronabinol could reduce cannabis self-administration among daily users. METHODS: Non-treatment seeking daily cannabis users (N = 13) completed a residential within-subjects crossover study and were administered placebo, low-dose dronabinol (120 mg/day; 40 mg tid), or high-dose dronabinol (180-240 mg/day; 60-80 mg tid) for 12 consecutive days (order counterbalanced). During each 12-day dronabinol maintenance phase, participants were allowed to self-administer smoked cannabis containing <1% THC (placebo) or 5.7% THC (active) under forced-choice (drug vs. money) or progressive ratio conditions. RESULTS: Participants self-administered significantly more active cannabis compared with placebo in all conditions. When active cannabis was available, self-administration was significantly reduced during periods of dronabinol maintenance compared with placebo maintenance. There was no difference in self-administration between the low- and high-dose dronabinol conditions. CONCLUSIONS: Chronic dronabinol dosing can reduce cannabis self-administration in daily cannabis users and suppress withdrawal symptoms. Cannabinoid agonist medications should continue to be explored for therapeutic utility in the treatment of cannabis use disorders.

Abstinence and reduced frequency of use are associated with improvements in quality of life among treatment-seekers with cannabis use disorder.

BACKGROUND AND OBJECTIVE: Many patients with cannabis use disorder (CUD) do not achieve or do not have abstinence as a goal of treatment, rather they reduce their use. Assessing outcome measures as they relate to functioning and reductions in cannabis use is an important area of study. Quality of life (QoL) shows promise as one such measure. Past studies have demonstrated gender differences in QoL and CUD. We aim to assess (1) the relationship between cannabis use and QoL and (2) gender effects in an outpatient medication treatment study for CUD. METHODS: Data from an 11-weeks, double-blind, placebo-controlled trial of lofexidine and dronabinol for CUD (n = 62) was analyzed. Pearson's correlations between baseline QoL as measured with the Quality of Life, Enjoyment, and Satisfaction Questionnaire-Short Form (QLES-Q-SF) and cannabis use assessed with modified timeline follow-back (TLFB) were examined. Multiple linear regression models of cannabis use on end of study QLES-Q-SF were analyzed, while adjusting for baseline QLES-Q-SF, study arm, and gender. Moderation effects with gender were also tested. RESULTS: No significant association between baseline cannabis use and QoL was found. End of study abstinence (F1,47 = 8.34, p = .006) and reduced proportion of using days (F1,47 = 9.48, p = .004) were each significantly associated with end of study QoL. Reduction in grams (F1,27 = 0.25, p = .62) was not associated with QoL at end of study. Gender was not a significant moderator. DISCUSSION AND CONCLUSIONS: Abstinence and lower frequency of use are associated with higher QoL, regardless of gender. SCIENTIFIC SIGNIFICANCE: This is the first time QoL has been demonstrated to change over the course of CUD medication treatment. QoL is an important outcome in CUD treatment. TRIAL REGISTRATION: NCT01020019. (Am J Addict 2018;27:101-107).

Medicinal cannabis (Bedrolite) substitution therapy in inpatients with a psychotic disorder and a comorbid cannabis use disorder: A case series.

Cannabis use disorders are frequently comorbid in patients with a psychotic disorder and are associated with worse outcomes. To date there are no proven effective strategies to achieve cannabis abstinence in this population. An alternative for abstinence might be harm reduction, i.e. replacing the use of street cannabis with high tetrahydrocannabinol and low cannabidiol levels by medicinal cannabis variants with relatively low tetrahydrocannabinol and relatively high cannabidiol levels, thereby reducing the psychosis inducing effects of cannabis and enhancing the antipsychotic effects of cannabis. Here we present the data of a case series with seven inpatients diagnosed with a psychotic disorder and a treatment-resistant cannabis use disorder who received substitution therapy with a low tetrahydrocannabinol medicinal cannabis variant (Bedrolite). The results suggest that the low tetrahydrocannabinol medicinal cannabis variant Bedrolite is not effective in the treatment of inpatients with a psychotic disorder and comorbid cannabis use disorder. Bedrolite is thus not very likely to become an effective harm reduction strategy in these patients.

A randomized placebo-controlled trial of N-acetylcysteine for cannabis use disorder in adults.

BACKGROUND: Cannabis use disorder (CUD) is a prevalent and impairing condition, and established psychosocial treatments convey limited efficacy. In light of recent findings supporting the efficacy of N-acetylcysteine (NAC) for CUD in adolescents, the objective of this trial was to evaluate its efficacy in adults. METHODS: In a 12-week double-blind randomized placebo-controlled trial, treatment-seeking adults ages 18-50 with CUD (N=302), enrolled across six National Drug Abuse Treatment Clinical Trials Network-affiliated clinical sites, were randomized in a 1:1 ratio to a 12-week course of NAC 1200mg (n=153) or placebo (n=149) twice daily. All participants received contingency management (CM) and medical management. The primary efficacy measure was the odds of negative urine cannabinoid tests during treatment, compared between NAC and placebo participants. RESULTS: There was not statistically significant evidence that the NAC and placebo groups differed in cannabis abstinence (odds ratio=1.00, 95% confidence interval 0.63-1.59, p=0.984). Overall, 22.3% of urine cannabinoid tests in the NAC group were negative, compared with 22.4% in the placebo group. Many participants were medication non-adherent; exploratory analysis within medication-adherent subgroups revealed no significant differential abstinence outcomes by treatment group. CONCLUSIONS: In contrast with prior findings in adolescents, there is no evidence that NAC 1200mg twice daily plus CM is differentially efficacious for CUD in adults when compared to placebo plus CM. This discrepant finding between adolescents and adults with CUD may have been influenced by differences in development, cannabis use profiles, responses to embedded behavioral treatment, medication adherence, and other factors.

A placebo controlled study of quetiapine-XR in bipolar depression accompanied by generalized anxiety with and without a recent history of alcohol and cannabis use.

OBJECTIVE: This study aims to compare treatment response in bipolar I or II depression and generalized anxiety disorder (GAD) with and without recent alcohol and/or cannabis use disorder (ALC/CAN) to quetiapine-XR (extended release) or placebo. METHODS: A randomized, double-blind, 8-week study of quetiapine-XR versus placebo in patients with bipolar I or II depression and GAD with or without a recent ALC/CAN was used to compare changes in Hamilton Depression Rating Scale-17, Hamilton Anxiety Rating Scale, the 16-item Quick Inventory of Depressive Symptomatology-Self-Report (QIDS-SR-16), Clinical Global Impression for Bipolar Disorder-Severity (CGI-BP-S), and Timeline Follow Back within and between groups. RESULTS: In the quetiapine-XR group, patients with a recent ALC/CAN (n = 22) had significant decreases in QIDS-SR-16 (-9.6 ± 1.6 vs. -3.7 ± 1.7) and CGI-BP-S (-1.6 ± 0.4 vs. -0.8 ± 0.03) than those without a recent ALC/CAN (n = 24). In the placebo group, both patients with a recent ALC/CAN (n = 23) and those without (n = 21) had similar reductions in these measures. The reduction of QIDS-SR-16 scores in patients with a recent ALC/CAN was also significantly different from that of their counterparts in the placebo group. Patients who received quetiapine-XR had larger decreases in the number of drinking days/week (p = 0.17) and number of cannabis joints/week (p = 0.09) compared to those who received placebo. CONCLUSION: Quetiapine-XR was superior to placebo in reducing QIDS-SR-16 total score in patients with a recent ALC/CAN. Patients taking quetiapine-XR used less alcohol and cannabis than patients on placebo, suggesting that quetiapine-XR may be of use in patients with bipolar disorder accompanied by GAD and other comorbidities.

Effects of zolpidem alone and in combination with nabilone on cannabis withdrawal and a laboratory model of relapse in cannabis users.

RATIONALE: Each year, over 300,000 individuals in the USA enter treatment for cannabis use disorder (CUD). The development of effective pharmacotherapy for CUD is a priority. OBJECTIVE: This placebo-controlled study examined the effects of zolpidem alone and in combination with nabilone on cannabis withdrawal and a laboratory measure of relapse. METHODS: Eleven daily, non-treatment-seeking cannabis users completed three, 8-day inpatient phases; each phase tested a different medication condition in counter-balanced order. On the first day of each phase, participants were administered placebo capsules t.i.d. and smoked experimenter-administered active cannabis (5.6 % Δ(9)-tetrahydrocannabinol (THC)). On days 2-8, the participants were administered capsules containing either placebo (0 mg at 0900, 1800, and 2300 hours), zolpidem (0 mg at 0900 and 1800, and 12.5 mg at 2300), or zolpidem (12.5 mg at 2300) and nabilone (3 mg at 0900 and 1800). Cannabis withdrawal, subjective capsule effects, and cognitive performance were examined on days 3-4, when only inactive cannabis (0.0 % THC) was available for self-administration. "Relapse" was measured on days 5-8, when participants could self-administer active cannabis. RESULTS: Both medication conditions decreased withdrawal-related disruptions in sleep, but only zolpidem in combination with nabilone decreased withdrawal-related disruptions in mood and food intake relative to placebo. Zolpidem in combination with nabilone, but not zolpidem alone, decreased self-administration of active cannabis. Zolpidem in combination with nabilone also produced small increases in certain abuse-related subjective capsule ratings, while zolpidem alone did not. Neither medication condition altered cognitive performance. CONCLUSIONS: Clinical testing of nabilone, either alone, or in combination with zolpidem is warranted.

Mixed-amphetamine salts increase abstinence from marijuana in patients with co-occurring attention-deficit/hyperactivity disorder and cocaine dependence.

BACKGROUND AND OBJECTIVES: The prevalence of ADHD is greater in substance use disorders than the general population, and ADHD and substance use disorders share neurobiological features such as dysregulation of reward circuitry. We tested the hypothesis that stimulants would decrease marijuana use in a randomized controlled trial of extended release mixed amphetamine salts (MAS-XR) for treatment of co-occurring ADHD and cocaine use disorders. METHODS: Marijuana users were defined as participants reporting use in the 30 days before study initiation, collected with timeline follow-back. The original 14-week trial utilized a 3-arm randomized design, comparing placebo, MAS-XR 60 mg, and MAS-XR 80 mg. For this analysis, both MAS-XR groups were combined, leaving n = 20 in the placebo group and n = 37 in the MAS-XR group. The primary outcome was proportion of subjects reporting any marijuana use per study week. Comparisons between groups were made using a logistic mixed effects model incorporating multiple predictors and modeling time-by-treatment interactions. RESULTS: There were no significant baseline differences in marijuana use frequency and quantity. There was a significant decrease in the proportion of participants using marijuana over time in the MAS-XR group, but no difference in the proportion of marijuana-use days over time. DISCUSSION AND CONCLUSIONS: Treatment of ADHD and comorbid cocaine use disorders with MAS-XR is associated with increased weekly abstinence from marijuana but not with a decrease in the proportion of marijuana using days per week. SCIENTIFIC SIGNIFICANCE: Stimulant treatment of ADHD and cocaine use disorders may diminish co-occurring cannabis use. (Am J Addict 2016;25:666-672).

Naltrexone Maintenance Decreases Cannabis Self-Administration and Subjective Effects in Daily Cannabis Smokers.

Given that cannabis use is increasing in the United States, pharmacological treatment options to treat cannabis use disorder are needed. Opioid antagonists modulate cannabinoid effects and may offer a potential approach to reducing cannabis use. In this double-blind, placebo-controlled human laboratory study, we assessed the effects of naltrexone maintenance on the reinforcing, subjective, psychomotor, and cardiovascular effects of active and inactive cannabis. Nontreatment-seeking, daily cannabis smokers were randomized to receive naltrexone (50 mg: n=18 M and 5 F) or placebo (0 mg; n=26 M and 2 F) capsules for 16 days. Before, during, and after medication maintenance, participants completed 10 laboratory sessions over 4-6 weeks, assessing cannabis' behavioral and cardiovascular effects. Medication compliance was verified by observed capsule administration, plasma naltrexone, and urinary riboflavin. Relative to placebo, maintenance on naltrexone significantly reduced both active cannabis self-administration and its positive subjective effects ('good effect'). Participants in the placebo group had 7.6 times (95% CI: 1.1-51.8) the odds of self-administering active cannabis compared with the naltrexone group. This attenuation of reinforcing and positive subjective effects also influenced cannabis use in the natural ecology. Naltrexone had intrinsic effects: decreasing ratings of friendliness, food intake, and systolic blood pressure, and increasing spontaneous reports of stomach upset and headache, yet dropout rates were comparable between groups. In summary, we show for the first time that maintenance on naltrexone decreased cannabis self-administration and ratings of 'good effect' in nontreatment-seeking daily cannabis smokers. Clinical studies in patients motivated to reduce their cannabis use are warranted to evaluate naltrexone's efficacy as a treatment for cannabis use disorder.

Acute effects of delta-9-tetrahydrocannabinol, cannabidiol and their combination on facial emotion recognition: a randomised, double-blind, placebo-controlled study in cannabis users.

Acute administration of the primary psychoactive constituent of cannabis, Δ-9-tetrahydrocannabinol (THC), impairs human facial affect recognition, implicating the endocannabinoid system in emotional processing. Another main constituent of cannabis, cannabidiol (CBD), has seemingly opposite functional effects on the brain. This study aimed to determine the effects of THC and CBD, both alone and in combination on emotional facial affect recognition. 48 volunteers, selected for high and low frequency of cannabis use and schizotypy, were administered, THC (8mg), CBD (16mg), THC+CBD (8mg+16mg) and placebo, by inhalation, in a 4-way, double-blind, placebo-controlled crossover design. They completed an emotional facial affect recognition task including fearful, angry, happy, sad, surprise and disgust faces varying in intensity from 20% to 100%. A visual analogue scale (VAS) of feeling 'stoned' was also completed. In comparison to placebo, CBD improved emotional facial affect recognition at 60% emotional intensity; THC was detrimental to the recognition of ambiguous faces of 40% intensity. The combination of THC+CBD produced no impairment. Relative to placebo, both THC alone and combined THC+CBD equally increased feelings of being 'stoned'. CBD did not influence feelings of 'stoned'. No effects of frequency of use or schizotypy were found. In conclusion, CBD improves recognition of emotional facial affect and attenuates the impairment induced by THC. This is the first human study examining the effects of different cannabinoids on emotional processing. It provides preliminary evidence that different pharmacological agents acting upon the endocannabinoid system can both improve and impair recognition of emotional faces.

Rivastigmine but not vardenafil reverses cannabis-induced impairment of verbal memory in healthy humans.

RATIONALE: One of the most often reported cognitive deficits of acute cannabis administration is an impaired recall of previously learned information. OBJECTIVE: The aim of the present study was to determine whether cannabis-induced memory impairment in humans is mediated via glutamatergic or cholinergic pathways. METHODS: Fifteen occasional cannabis users participated in a double-blind, placebo-controlled, six-way cross-over study. On separate test days, subjects received combinations of pretreatment (placebo, vardenafil 20 mg or rivastigmine 3 mg) and treatment (placebo or 1,376 mg cannabis/kg body weight). Cognitive tests were administered immediately after inhalation of treatment was finished and included measures of memory (visual verbal learning task, prospective memory test, Sternberg memory test), perceptual-motor control (critical tracking task), attention (divided attention task) and motor impulsivity (stop signal task). RESULTS: The results of this study demonstrate that subjects under the influence of cannabis were impaired in all memory tasks, in critical tracking, divided attention and the stop signal task. Pretreatment with rivastigmine attenuated the effect of cannabis on delayed recall and showed a trend towards significance on immediate recall. When cannabis was given in combination with vardenafil, there were no significant interaction effects in any of the tasks. CONCLUSIONS: The present data therefore suggest that acetylcholine plays an important role in cannabis-induced memory impairment, whereas similar results for glutamate have not been demonstrated in this study.

Do withdrawal-like symptoms mediate increased marijuana smoking in individuals treated with venlafaxine-XR?

BACKGROUND AND AIMS: Cannabis-dependent participants with depressive disorder are less likely to achieve abstinence with venlafaxine-XR (VEN-XR) treatment. Individuals on VEN-XR reported more severe withdrawal, despite not reducing their smoking behavior. We hypothesized that withdrawal-like symptoms, likely medication side effects, led to continued marijuana smoking in this group. METHODS: We conducted a secondary analysis using Marijuana Withdrawal Checklist (MWC) scores and urine THC to test whether severity of withdrawal-like symptoms mediates the relationship between VEN-XR treatment and continued marijuana smoking. We included 103 participants (VEN-XR=51, Placebo=52). Marijuana use was dichotomized into smoking (THC>100 ng/ml) and non-smoking (THC ≤ 100 ng/ml) weeks. MWC scores were obtained weekly. We used three models in a regression based mediation analysis. RESULTS: The estimated risk of smoking marijuana was greater for individuals on VEN-XR in weeks 7-9, even when controlling for MWC scores (week 7 Risk Difference (RD)=0.11, p=0.034; week 8 RD=0.20, p=0.014), and higher scores mediated this effect. In weeks 10 and 11, the estimated effect was stronger (week 10 RD=0.03, p=0.380; week 11 RD=0.07, p=0.504), and worse withdrawal-like symptoms more fully accounted for continued marijuana smoking in the VEN-XR group, according to the models. CONCLUSIONS: Individuals treated with VEN-XR had more severe withdrawal-like symptoms, which mediated their continued marijuana smoking. Noradrenergic agents, such as VEN-XR, may negatively impact treatment outcomes in cannabis-dependent patients attempting to reduce or stop their use.

Cigarette smoking during an N-acetylcysteine-assisted cannabis cessation trial in adolescents.

BACKGROUND AND OBJECTIVES: Tobacco and cannabis use are both highly prevalent worldwide. Their co-use is also common in adults and adolescents. Despite this frequent co-occurrence, cessation from both substances is rarely addressed in randomized clinical trials. Given evidence that tobacco use may increase during cannabis cessation attempts, and additionally that tobacco users have poorer cannabis cessation outcomes, we explored tobacco outcomes, specifically cigarette smoking, from an adolescent cannabis cessation trial that tested the efficacy of N-acetylesteine (NAC). METHODS: Cannabis-dependent adolescents (ages 15-21; n = 116) interested in cannabis treatment were randomized to NAC (1200 mg bid) or matched placebo for 8 weeks. Participants did not need to be cigarette smokers or be interested in smoking cessation to qualify for inclusion. RESULTS: Approximately 59% of enrolled participants were daily and non-daily cigarette smokers, and only differed from non-smoking participants on the compulsion sub-scale of the Marijuana Craving Questionnaire. Among cigarette smokers who were retained in the study, there was no change in cigarettes per day for either NAC or placebo groups during the eight-week treatment phase. Being a cigarette smoker did not appear to influence the effects of NAC on cannabis abstinence, though there was a trend in the placebo group of poorer cannabis outcomes for cigarette smokers vs. non-smokers. CONCLUSIONS: No evidence was found of compensatory cigarette smoking during this cannabis cessation trial in adolescents. Further work assessing interventions to reduce both cannabis and tobacco use in this population is greatly needed.

Evidence summary: the therapeutic effectiveness of Cannabis sativa

This Evidence Summary is prepared in response to a request from the Assistant Secretary-General, Human and Social Development, CARICOM. Given the debate internationally with respect to Cannabis sativa’s safety and efficacy, and given that CARPHA’s role is to provide direction in analyzing, defining and responding to public health priorities, we have interpreted this broad request as requiring our response to the following question: What is the current state of scientific knowledge regarding the effectiveness of marijuana and its chemical constituents in medical treatment in humans? We present a synthesis of research findings, of international relevance, that answers the specified question.