The pharmacologic effects of daily marijuana smoking in humans

Controversial Link between Cannabis and Anticancer Treatments-Where Are We and Where Are We Going? A Systematic Review of the Literature

Simple Summary

In the field of oncology, preclinical research has shown that cannabis and cannabinoids modulate signaling pathways involved in cell proliferation, migration, invasion, angiogenesis, programmed cell death, and metastasis. Based on these findings, as medical cannabis becomes legal in more and more countries, cancer patients and their families are increasingly interested in the potential benefits of herbal medicine as an element of complementary and alternative medicine in their treatment. Although its clinical efficacy has been demonstrated in preclinical studies, clinical trials with cancer patients are lacking. To draw clear conclusions, we await the results of further prospective and randomized studies on this clinically relevant topic.

Abstract

Background and Objectives: Cannabinoids are currently used in cancer patients primarily for their pain-relieving and antiemetic properties. The aim of our review was to synthesize all available data of studies evaluating the therapeutic efficacy of cannabis in combination with oncological treatments in cancer patients and to explore ongoing studies with different goals and medical areas registered in the field of oncology worldwide. Materials and Methods: This study was performed in accordance with the PRISMA guidelines. A search using MEDLINE/PubMed database was performed between 1 January 2006 and 1 March 2022. Search terms included the following: cannabidiol, cannabis, CBD, dronabinol, endocannabinoids, medical marijuana, nabiximols, nabilone, THC, and cancer. All studies that examined the efficacy of cannabis administered during oncological treatments, regardless of cancer localization, subtype, and sample size, were considered eligible. Results: In three studies, cannabis was administered to patients with glioblastoma, and in two other studies, cannabis was used in combination with immunotherapy in various cancer subgroups. The results of the clinical trials in cancer patients are not sufficient to draw conclusions at this time. Interestingly, several other studies addressing the systemic effects of cannabinoids in cancer patients are currently listed in the U.S. National Library of Medicine’s registry on the ClinicalTrials.gov website. However, only one of the registered studies examined the efficacy of cannabinoids as a potential option for systemic cancer treatment. Conclusions: Although cannabis is touted to the public as a cancer cure, clinical trials need to clarify which combinations of chemotherapeutic agents with cannabinoids are useful for cancer patients.

Pharmacokinetics of Cannabis and Its Derivatives in Animals and Humans During Pregnancy and Breastfeeding

Cannabis is one of the most widely used illicit drugs during pregnancy and lactation. With the recent legalization of cannabis in many countries, health professionals are increasingly exposed to pregnant and breastfeeding women who are consuming cannabis on a regular basis as a solution for depression, anxiety, nausea, and pain. Cannabis consumption during pregnancy can induce negative birth outcomes such as reduced birth weight and increased risk of prematurity and admission to the neonatal intensive care unit. Yet, limited information is available regarding the pharmacokinetics of cannabis in the fetus and newborn exposed during pregnancy and lactation. Indeed, the official recommendations regarding the use of cannabis during these two critical development periods lack robust pharmacokinetics data and make it difficult for health professionals to guide their patients. Many clinical studies are currently evaluating the effects of cannabis on the brain development and base their groups mostly on questionnaires. These studies should be associated with pharmacokinetics studies to assess correlations between the infant brain development and the exposure to cannabis during pregnancy and breastfeeding. Our project aims to review the available data on the pharmacokinetics of cannabinoids in adults, neonates, and animals. If the available literature is abundant in adult humans and animals, there is still a lack of published data on the exposure of pregnant and lactating women and neonates. However, some of the published information causes concerns on the exposure and the potential effects of cannabis on fetuses and neonates. The safety of cannabis use for non-medical purpose during pregnancy and breastfeeding needs to be further characterized with proper pharmacokinetic studies in humans feasible in regions where cannabis has been legalized. Given the available data, significant transfer occurs to the fetus and the breastfed newborn with a theoretical risk of accumulation of products known to be biologically active.

Cannabis and Its Different Strains

Previous studies show how time perception can be altered by cannabis consumption, but it is not clear yet whether cannabis produces temporal underproductions or overproductions after acute cannabis intoxication. The present study aimed to analyze a sample of 50 regular cannabis users controlling for cannabis strain (sativa, indica, and hybrid) and to compare their scores in a temporal production task before and after consuming cannabis with a control group of 49 nonusers. Results showed that cannabis intake leads to overproductions, suggesting that regular users' internal tempo slows down after acute intoxication. However, the analyses of main effects showed that indica users, both at baseline levels and after consuming, reported significant underproductions compared to controls, sativa, and hybrid users, and the cannabis-induced effects had a higher magnitude after smoking in the indica-strain group. Results highlight the relevance of including the type of strain consumed in cannabis studies, and they are discussed in terms of short- and long-term alterations in temporal perception under the light of the self-medication theory and the therapeutic uses of cannabis.

Chronic cannabinoid exposure produces tolerance to the dopamine releasing effects of WIN 55,212-2 and heroin in adult male rats

Synthetic cannabinoids were introduced into recreational drug culture in 2008 and quickly became one of the most commonly abused drugs in the United States. The neurobiological consequences resulting from synthetic cannabinoid repeated exposure remain poorly understood. It is possible that a blunted dopamine (DA) response may lead drug users to consume larger quantities to compensate for this form of neurochemical tolerance. Because the endogenous cannabinoid and opioid systems exhibit considerable cross-talk and cross-tolerance frequently develops following repeated exposure to either opioids or cannabinoids, there is interest in investigating whether a history of synthetic cannabinoid exposure influences the ability of heroin to increase DA release. To test the effects of chronic cannabinoid exposure on cannabinoid- and heroin-evoked DA release, male adult rats were treated with either vehicle or a synthetic cannabinoid (WIN55-212-2; WIN) using an intravenous (IV) dose escalation regimen (0.2-0.8 mg/kg IV over 9 treatments). As predicted, WIN-treated rats showed a rightward shift in the dose-response relationship across all behavioral/physiological measures when compared to vehicle-treated controls. Then, using fast-scan cyclic voltammetry to measure changes in the frequency of transient DA events in the nucleus accumbens shell of awake and freely-moving rats, it was observed that the DA releasing effects of both WIN and heroin were significantly reduced in male rats with a pharmacological history of cannabinoid exposure. These results demonstrate that repeated exposure to the synthetic cannabinoid WIN can produce tolerance to its DA releasing effects and cross-tolerance to the DA releasing effects of heroin.

Adverse events following cannabis for medical use in Tuscany: An analysis of the Italian Phytovigilance database

AIMS

Despite a significant increase in using cannabis for medical purposes, current evidence on its safety in real-world clinical practice is still poorly characterised. By a case-by-case analysis of spontaneous reports of suspected adverse events (AEs) collected in Tuscany within the Italian Phytovigilance database, the aim of the present study was to describe AEs occurred in patients exposed to medical cannabis.

METHODS

We evaluated all reports of cannabis-related suspected AEs collected within the Phytovigilance database up to December 2018. Information regarding cannabis therapy, patient's demographic and clinical characteristics, concomitant medications, AE description according to the Medical Dictionary for Regulatory Activities (MedDRA) classification, AE seriousness and AE outcome, were collected. The causality assessment was performed following World Health Organisation-Uppsala Monitoring Centre criteria.

RESULTS

Fifty-three cannabis-related AE reports were analysed. The majority of patients were females (77.3%), with a mean age of 61.9 years. Thirty-nine (73.6%) cases were defined as nonserious and the majority of them (86.9%) showed a complete resolution or improvement. Forty-six (86.8%) cases were judged as probably related to cannabis consumption. The most frequently reported system organ class was psychiatric and nervous system disorders, and a potential drug-drug interaction was present in 16 cases.

CONCLUSION

Cannabis was generally well tolerated and the majority of AEs were mild and transient. Our analysis highlighted important safety issues for clinical practice, in particular the need for an accurate prescription monitoring during the titration phase, particularly in the presence of concomitant medications.

Spontaneous, anecdotal, retrospective, open-label study on the efficacy, safety and tolerability of cannabis galenical preparation (Bedrocan)

OBJECTIVES

Our main aim was to investigate the short-term therapeutic effects, safety/tolerability and potential side effects of the cannabis galenical preparation (Bedrocan) in patients with a range of chronic conditions unresponsive to other treatments.

METHODS

In this retrospective, 'compassionate use', observational, open-label study, 20 patients (age 18-80 years) who had appealed to our 'Second Opinion Medical Consulting Network' (Modena, Italy), were instructed to take sublingually the galenical oil twice a day for 3 months of treatment. The usual starting dose was low (0.5 ml/day) and gradually titrated upward to the highest recommended dose (1 ml/day). Tolerability and adverse effects were assessed at baseline and monthly thereafter during the treatment period through direct contact (email or telephone) or visit if required. Patients' quality of life was evaluated at baseline and 3 months using the medical outcome short-form health survey questionnaire (SF-36).

KEY FINDINGS

From baseline to 6 months post-treatment, SF-36 scores showed: reductions in total pain (P < 0.03); improvements in the physical component (P < 0.02); vitality (P < 0.03); social role functioning (P < 0.02); and general health state (P < 0.02). No changes in role limitations (P = 0.02) due to emotional state (e.g. panic, depression, mood alteration) were reported. Monthly reports of psychoactive adverse effects showed significant insomnia reduction (P < 0.03) and improvement in mood (P < 0.03) and concentration (P < 0.01).

CONCLUSIONS

These data suggest that a cannabis galenical preparation may be therapeutically effective and safe for the symptomatic treatment of some chronic diseases. Further studies on the efficacy of cannabis as well as cannabinoid system involvement in the pathophysiology are warranted.

Cannabinoids concentration variability in cannabis olive oil galenic preparations

OBJECTIVES

Knowledge of the exact concentration of active compounds in galenic preparations is crucial to be able to ensure their quality and to properly administer the prescribed dose. Currently, the need for titration of extracts is still debated. Considering this, together with the absence of a standard preparation method, the aim of this study was to evaluate cannabinoids concentrations variability in galenic olive oil extracts, to evaluate the interlot and interlaboratory variability in the extraction yield and in the preparation composition.

METHODS

Two hundred and one extracts (123 (61.2%) from Bedrocan^® , 54 (26.9%) from Bediol^® , 11 (5.5%) from Bedrolite^® , and 13 (6.5%) from mixed preparations) were analysed by liquid chromatography coupled with tandem mass spectrometry, quantifying cannabinoids (THC, CBD, THCA, CBDA and CBN) concentrations.

KEY FINDINGS

The RSD% of THC and CBD concentrations resulted higher than 50%. Specifically for Bedrocan^® , Bediol^® , Bedrolite^® (5 g/50 ml), these were THC 82%, THC 53% and CBD 91%, THC 58% and CBD 59%, respectively. The median extraction yields were greater than 75% for all preparations.

CONCLUSIONS

Our results highlighted a wide variability in THC and CBD concentrations that justify the need for titration and opens further questions about other pharmaceutical preparations without regulatory indication for this procedure.

Behavioral Determinants of Cannabinoid Self-Administration in Old World Monkeys

Reinforcing effects of Δ⁹-tetrahydrocannabinol (THC), the primary active ingredient in marijuana, as assessed with self-administration (SA), has only been established in New World primates (squirrel monkeys). The objective of this study was to investigate some experimental factors that may enhance intravenous SA of THC and the cannabinoid receptor (CBR) agonist CP 55 940 in Old World monkeys (rhesus and cynomolgus), a species that has been used extensively in biomedical research. In one experiment, male rhesus monkeys (N=9) were trained to respond under a fixed-ratio 10 schedule of food presentation. The effects of CP 55 940 (1.0-10 μg/kg, i.v.) and THC (3.0-300 μg/kg, i.v.) on food-maintained responding and body temperature were determined in these subjects prior to giving them access to self-administer each drug. Both drugs dose-dependently decreased food-maintained responding. CP 55 940 (0.001-3.0 μg/kg) functioned as a reinforcer in three monkeys, whereas THC (0.01-10 μg/kg) did not have reinforcing effects in any subject. CP 55 940 was least potent to decrease food-maintained responding in the monkeys in which CP 55 940 functioned as a reinforcer. Next, THC was administered daily to monkeys until tolerance developed to rate-decreasing effects. When THC SA was reexamined, it functioned as a reinforcer in three monkeys. In a group of cocaine-experienced male cynomolgus monkeys (N=4), THC SA was examined under a second-order schedule of reinforcement; THC functioned as reinforcer in two monkeys. These data suggest that SA of CBR agonists may be relatively independent of their rate-decreasing effects in Old World monkeys. Understanding individual differences in vulnerability to THC SA may lead to novel treatment strategies for marijuana abuse.

Acute subjective effects after smoking joints containing up to 69 mg Δ9-tetrahydrocannabinol in recreational users: a randomized, crossover clinical trial

RATIONALE

An increase in the potency of the cannabis cigarettes has been observed over the past three decades.

OBJECTIVES

In this study, we aimed to establish the impact of Δ9-tetrahydrocannabinol (THC) on the rating of subjective effects (intensity and duration of the effects), up to 23 % THC potency (69 mg THC) among recreational users.

METHODS

Recreational users (N = 24) smoked cannabis cigarettes with four doses of THC (placebo 29, 49 and 69 mg of THC) on four separate test days in a randomized, double-blind, placebo-controlled, crossover study. The participants filled in three different questionnaires measuring subjective effects during the exposure up to 8 h post-smoking. The 'high' feeling, heart rate, blood pressure and THC serum concentrations were also regularly recorded during these 8 h.

RESULTS

THC significantly increased the high feeling, dizziness, dry-mouthed feeling, palpitations, impaired memory and concentration, and 'down', 'sedated' and 'anxious' feelings. In addition, THC significantly decreased alertness, contentment and calmness. A cubic relationship was observed between 'feeling the drug' and 'wanting more'. The THC-induced decrease in 'feeling stimulated' and increase in anxiety lasted up to 8 h post-smoking. Sedation at 8 h post-smoking was increased by a factor of 5.7 with the highest THC dose, compared to the placebo.

CONCLUSIONS

This study shows a strong effect of cannabis containing high percentages of THC on the rating of subjective effects. Regular users and forensic toxicologists should be aware that the THC-induced increase in 'feeling sedated' continues longer with a 69 mg THC dose than with a 29 mg THC dose.

Cannabinoid modulations of resting state EEG θ power and working memory are correlated in humans

Object representations in working memory depend on neural firing that is phase-locked to oscillations in the theta band (4-8 Hz). Cannabis intake disrupts synchronicity of theta oscillations and interferes with memory performance. Sixteen participants smoked cigarettes containing 0.0, 29.3, 49.1, or 69.4 mg Delta(9)-tetrahydrocannabinol (THC) in a randomized crossover design and performed working memory and general attention tasks. Dose-dependent effects of THC were observed for resting state EEG theta and beta power, working memory (per-item search time), and attentional performance (percent errors and RT). The THC effects on EEG theta power and memory performance were correlated, whereas other EEG and behavioral effects were not. These findings confirm and extend previous results in rodents and humans, and corroborate a neurocomputational model that postulates that temporal aspects of information processing in working memory depend causally on nested oscillations in the theta and gamma (>30 Hz) bands.

Selective lack of tolerance to delayed gastric emptying after daily administration of WIN 55,212-2 in the rat

The use of cannabinoids to treat gastrointestinal (GI) motor disorders has considerable potential. However, it is not clear if tolerance to their actions develops peripherally, as it does centrally. The aim of this study was to examine the chronic effects of the cannabinoid agonist WIN 55,212-2 (WIN) on GI motility, as well as those in the central nervous and cardiovascular systems. WIN was administered for 14 days, at either non-psychoactive or psychoactive doses. Cardiovascular parameters were measured in anaesthetized rats, whereas central effects and alterations in GI motor function were assessed in conscious animals using the cannabinoid tetrad and non-invasive radiographic methods, respectively. Tests were performed after first (acute effects) and last (chronic effects) administration of WIN, and 1 week after discontinuing treatment (residual effects). Food intake and body weight were also recorded throughout treatment. Blood pressure and heart rate remained unchanged after acute or chronic administration of WIN. Central activity and GI motility were acutely depressed at psychoactive doses, whereas non-psychoactive doses only slightly reduced intestinal transit. Most effects were reduced after the last administration. However, delayed gastric emptying was not and could, at least partially, account for a concomitant reduction in food intake and body weight gain. The remaining effects of WIN administration in GI motility were blocked by the CB1 antagonist AM 251, which slightly accelerated motility when administered alone. No residual effects were found 1 week after discontinuing cannabinoid treatment. The different systems show differential sensitivity to cannabinoids and tolerance developed at different rates, with delayed gastric emptying being particularly resistant to attenuation upon chronic treatment.

Cannabinoids and the human uterus during pregnancy

OBJECTIVE

The aim of this study was to investigate the expression of cannabinoid receptors in human uterine smooth muscle during pregnancy and to evaluate the effects of endogenous and exogenous cannabinoids on myometrial contractility in vitro.

STUDY DESIGN

Human myometrial biopsy specimens were obtained at elective cesarean delivery and snap frozen or mounted for isometric recording under physiologic conditions. Cumulative doses of the endogenous cannabinoid anandamide or the exogenous cannabinoid Delta(9) (indicates a double bond between carbons 9 and 10) tetrahydrocannabinol were added in the range 1 nmol/L to 100 micromol/L. Selectivity of the cannabinoid receptor agonists was investigated with specific antagonists for the CB(1) and the CB(2) receptors. Reverse transcription-polymerase chain reaction with primers for the CB(1) and CB(2) receptors was performed on messenger RNA that was isolated from human pregnant myometrium.

RESULTS

Both anandamide and Delta(9)-tetrahydrocannabinol exerted a direct relaxant effect on human pregnant myometrium in vitro, which was of equal potency for both compounds. This relaxant effect was antagonized by the specific CB(1) receptor antagonist, SR 141716, but not by the specific CB(2) receptor antagonist, SR 144528 (n=6 specimens, P<.01). Both the CB(1) and CB(2) receptors are expressed in human myometrium.

CONCLUSIONS

Both endogenous and exogenous cannabinoids exert a potent and direct relaxant effect on human pregnant myometrium, which is mediated through the CB(1) receptor. This highlights a possible role for endogenous cannabinoids during human parturition and pregnancy. These results also support the view that the use of exogenous cannabinoids during pregnancy is not linked independently with preterm labor.

Effects of chronic Delta(9)-tetrahydrocannabinol treatment on hippocampal extracellular acetylcholine concentration and alternation performance in the T-maze

Delta(9)-Tetrahydrocannabinol (Delta(9)-THC), the psychoactive ingredient of cannabis sativa, reduces both extracellular hippocampal acetylcholine concentration and correct alternation tasks in the T-maze. The principal aim of this study was to determine whether a chronic Delta(9)-THC treatment would induce tolerance both to the reduction of extracellular hippocampal acetylcholine concentration and memory deficit produced by the drug. Our results show that a chronic Delta(9)-THC treatment (5mg/kg, i.p., twice daily for two weeks) did not produce tolerance to the inhibitory effects induced by the drug. Moreover, no strict temporal correlation between the two Delta(9)-THC effects was observed: the inhibition in extracellular acetylcholine concentration appeared only 80 min after treatment, while the reduction of correct alternation tasks in the T-maze began after 20 min. The cognitive and cholinergic effects induced by a chronic Delta(9)-THC treatment were completely blocked by the CB(1) cannabinoid receptor antagonist SR 141716A, indicating an involvement of CB(1) cannabinoid receptors in the persistent negative effects induced by the drug. These findings confirm the proposition that CB(1) cannabinoid receptors mediate the negative effects induced by Delta(9)-THC both on hippocampal extracellular acetylcholine concentration and correct alternation tasks in the T-maze, and they indicate that these effects may be differentiated. However, the major outcome of this work is the demonstration that no tolerance to the two inhibitory effects develops after a chronic Delta(9)-THC treatment.

Effects of chronic delta9-tetrahydrocannabinol on rat midbrain dopamine neurons: an electrophysiological assessment

Delta-9-tetrahydrocannabinol (delta9-THC), the principal psychoactive ingredient in marijuana elicits a variety of physiological effects in animals and humans, and with repeated exposure tolerance develops to most of its effects. However, studies in humans found that tolerance did not occur to the pleasurable marijuana "high". Since ventral tegmental dopamine neurons play a pivotal role in drug reinforcement and reward, and possibly in the euphorigenic quality of marijuana, the present study sought to determine whether tolerance develops to the neurophysiological response elicited in these neurons by delta9-THC. Using single-unit extracellular recordings the activity of midbrain ventral tegmental (VTA) and substantia nigra pars compacta (SNpc) dopamine neurons was measured in animals that had received twice-daily injections of 5 mg/kg delta9-THC for 14 days. Cannabinoid-induced changes in body temperature, locomotion, and catalepsy were also assessed in the same animals. After 2 weeks tolerance had developed to delta9-THC-induced hypothermia, catalepsy and reduction in locomotor activity. In naive animals and in animals that had received twice-daily vehicle injections for 14 days, delta9-THC increased VTA neuronal firing by 52% and 46%, respectively, while SNpc neurons showed increases of 23% and 30%, respectively. Following chronic cannabinoid treatment, however, SNpc neurons were significantly less responsive to delta9-THC with a maximum increase in rate of only 3%, while VTA neurons continued to show a robust increase in firing rate (+45%) when challenged with THC. These results suggest that VTA and SNpc dopamine neurons develop a differential response to delta9-THC following long-term cannabinoid exposure. This finding may be relevant to the observation that in humans tolerance occurs to many of marijuana's physiological effects but not to its euphorigenic actions.

The effects of cannabinoids on the brain

Cannabinoids have a long history of consumption for recreational and medical reasons. The primary active constituent of the hemp plant Cannabis sativa is delta9-tetrahydrocannabinol (delta9-THC). In humans, psychoactive cannabinoids produce euphoria, enhancement of sensory perception, tachycardia, antinociception, difficulties in concentration and impairment of memory. The cognitive deficiencies seem to persist after withdrawal. The toxicity of marijuana has been underestimated for a long time, since recent findings revealed delta9-THC-induced cell death with shrinkage of neurons and DNA fragmentation in the hippocampus. The acute effects of cannabinoids as well as the development of tolerance are mediated by G protein-coupled cannabinoid receptors. The CB1 receptor and its splice variant CB1A, are found predominantly in the brain with highest densities in the hippocampus, cerebellum and striatum. The CB2 receptor is found predominantly in the spleen and in haemopoietic cells and has only 44% overall nucleotide sequence identity with the CB1 receptor. The existence of this receptor provided the molecular basis for the immunosuppressive actions of marijuana. The CB1 receptor mediates inhibition of adenylate cyclase, inhibition of N- and P/Q-type calcium channels, stimulation of potassium channels, and activation of mitogen-activated protein kinase. The CB2 receptor mediates inhibition of adenylate cyclase and activation of mitogen-activated protein kinase. The discovery of endogenous cannabinoid receptor ligands, anandamide (N-arachidonylethanolamine) and 2-arachidonylglycerol made the notion of a central cannabinoid neuromodulatory system plausible. Anandamide is released from neurons upon depolarization through a mechanism that requires calcium-dependent cleavage from a phospholipid precursor in neuronal membranes. The release of anandamide is followed by rapid uptake into the plasma and hydrolysis by fatty-acid amidohydrolase. The psychoactive cannabinoids increase the activity of dopaminergic neurons in the ventral tegmental area-mesolimbic pathway. Since these dopaminergic circuits are known to play a pivotal role in mediating the reinforcing (rewarding) effects of the most drugs of abuse, the enhanced dopaminergic drive elicited by the cannabinoids is thought to underlie the reinforcing and abuse properties of marijuana. Thus, cannabinoids share a final common neuronal action with other major drugs of abuse such as morphine, ethanol and nicotine in producing facilitation of the mesolimbic dopamine system.

Responses to oral delta9-tetrahydrocannabinol in frequent and infrequent marijuana users

It is known that an individual's drug use history affects the quality of subjective effects experienced following administration of several clinically used psychoactive drugs such as barbiturates, diazepam, and morphine. However, it is not known whether drug use history also affects responses to therapeutic cannabinoids such as delta9-THC. The current experiment compared the subjective and behavioral effects of oral delta9-THC in two groups of volunteers: frequent users (FREQ; n = 11), who reported using marijuana at least 100 times, and infrequent users (INF; n = 10) who reported using marijuana 10 or fewer times. Subjects participated in three sessions during which they received delta9-THC (7.5 and 15 mg) and placebo. They completed subjective effects questionnaires for 5 h following administration. In the FREQ group, the lower dose (7.5 mg) increased ratings of "feel drug," relative to placebo, whereas it had no effect in the INF group. In contrast, at the higher dose (15 mg), ratings of "feel drug" were lower in the FREQ group than in the INF group, suggestive of tolerance. In addition, the INF group reported greater sedative effects than the FREQ group following the higher dose of delta9-THC, again suggesting tolerance to delta9-THC's sedative effects. These findings demonstrate that marijuana use history may affect the subjective effects of oral delta9-THC, but that the influence of drug use history depends on the dose of drug administered. These findings may have implications for the clinical use of delta9-THC and other cannabinoids.

Comparative effects of alcohol and marijuana on mood, memory, and performance

This study compared subjective and behavioral effect profiles of alcohol and smoked marijuana using technology that controlled puffing and inhalation parameters. Male volunteers (n = 5) with histories of moderate alcohol and marijuana use were administered three doses of alcohol (0.25, 0.5, or 1.0 g/kg), three doses of marijuana [4.8, or 16 puffs of 3.55% delta 9-tetrahydrocannabinol (THC)], and placebo in random order under double blind conditions in seven separate sessions. Blood alcohol concentration (10-90 mg/dl) and THC levels (63-188 ng/ml) indicated that active drug was delivered to subjects dose dependently. Alcohol and marijuana produced dose-related changes in subjective measures of drug effect. Ratings of perceived impairment were identical for the high doses of alcohol and marijuana. Both drugs produced comparable impairment in digit-symbol substitution and word recall tests, but had no effect in time perception and reaction time tests. Alcohol, but not marijuana, slightly impaired performance in a number recognition test. These data are useful for understanding the relative performance impairment produced by alcohol and marijuana at the delivered doses and the relationship between their subjective and behavioral effects.

Determination of delta 9-tetrahydrocannabinol from human saliva by tandem immunoaffinity chromatography--high-performance liquid chromatography

Smoking or ingestion of cannabis causes cognitive, perceptual and behavioural changes, which are responsive for impaired performance in driving motor vehicles. In this paper a novel liquid chromatographic assay for the selective quantification of delta 9-tetrahydrocannabinol, the major indicator of a present cannabis intoxication in saliva, is described. The method involves a column-switching procedure and requires an extremely simple pre-treatment of the sample. Deproteinized saliva was directly injected into the chromatographic system. The clean-up and enrichment procedure was performed in an immunoaffinity column, followed by the transfer of the antigens to an octysilica analytical column. The immunoaffinity sorbent was obtained by covalent immobilization of specific antibodies on epoxy-activated silica. The mobile phase consisted of methanol-aqueous 0.15 mol/1 NaCl solution (elution programmed) and the analyte was detected by measuring the UV absorption at 220 nm. Using an injection volume of 4.5 ml (dilution 3:2, v/v) the limit of quantification was 20 ng/ml, at a signal-to-noise ratio of 5. Recoveries were estimated to be in the range of 70%. Both intra- and inter- day coefficients of variation were below 5%.

Chronic cannabinoid administration alters cannabinoid receptor binding in rat brain: a quantitative autoradiographic study

The active ingredient of marijuana is (-)-delta 9-tetrahydrocannabinol (delta 9-THC). delta 9-THC and other natural and synthetic cannabinoids such as CP-55,940 inhibit spontaneous activity and produce catalepsy in animals in a receptor-mediated fashion. Tolerance develops to the motor effects of delta 9-THC after repeated administration. To test the hypothesis that tolerance is mediated by changes in cannabinoid receptor binding characteristics, we used quantitative in vitro autoradiography of [3H]CP-55,940 binding to striatal brain sections from rats treated either chronically or acutely with delta 9-THC, CP-55,940, or the inactive natural cannabinoid cannabidiol. In the chronic conditions, rats were given daily i.p. injections of delta 9-THC (10 mg/kg), cannabidiol (10 mg/kg), or CP-55,940 (1, 3, or 10 mg/kg) for 2 weeks and sacrificed 30 min after the last injection. In the acute condition, animals received a single dose (10 mg/kg) prior to sacrifice. Rats developed tolerance to the inhibitory effects of delta 9-THC and CP-55,940, assayed in an open field on days 1, 7, and 14. Cannabidiol had no effect on behavior. Densitometry of [3H]CP-55,940 binding to brain sections showed that delta 9-THC- and CP-55,940-treated animals had homogeneous decreases in binding in all structures measured at the selected striatal levels. Cannabidiol had no effect on binding. Analysis of binding parameters showed that alterations in the acute condition were attributed to changes in affinity (KD), whereas the major changes in the chronic condition were attributed to a lowering of capacity (Bmax). The effects in the 1, 3, and 10 mg/kg CP-55,940 conditions were dose-dependent and paralleled the behavioral data showing that the animals given the highest dose developed the greatest degree of tolerance. The data suggest that tolerance to cannabinoids results at least in part from agonist-induced receptor down-regulation.