METABOLISM AND DISPOSITION OF TETRAHYDROCANNABINOLS IN NÄIVE SUBJECTS AND CHRONIC MARIJUANA USERS

Sex differences in the acute effects of oral THC: a randomized, placebo-controlled, crossover human laboratory study

RATIONALE

Recent reports have shown increased cannabis use among women, leading to growing concerns about cannabis use disorder (CUD). While there is preclinical evidence suggesting biological sex influences cannabinoid effects, human research remains scant. We investigated sex differences in the acute response to oral tetrahydrocannabinol (THC) in humans.

METHODS

56 healthy men and women with prior exposure to cannabis but no history of CUD participated in a randomized, placebo-controlled, human laboratory study where they received a single 10 mg dose of oral THC (dronabinol). Subjective psychoactive effects were assessed by the visual analog scale of "high", psychotomimetic effects by the Clinician-Administered Dissociative Symptoms Scale and Psychotomimetic States Inventory, verbal learning and memory by Rey Auditory Verbal Learning Test (RAVLT), and physiological effects by heart rate. Outcomes were regularly measured on the test day, except for the RAVLT, which was assessed once. Peak differences from baseline were analyzed using a nonparametric method for repeated measures.

RESULTS

Oral THC (10 mg) demonstrated significant dose-related effects in psychotomimetic and physiological domains, but not in RAVLT outcomes. A notable interaction between THC dose and sex emerged concerning the subjective "high" scores, with women reporting heightened sensations (p = 0.05). No other significant effects of sex and THC dose interaction were observed.

CONCLUSION

Oral THC (10 mg) yields similar acute psychotomimetic and physiological effects across sexes, but women may experience a pronounced subjective psychoactive effect. Further research is needed to identify individual vulnerabilities and facilitate tailored interventions addressing CUD.

CLINICALTRIALS

GOV REGISTRATION: https://clinicaltrials.gov/study/NCT02781519?term=Ranganathan&intr=THC&rank=3 .

Sex Differences in the Acute Effects of Oral THC: A Randomized, Placebo-Controlled, Crossover Human Laboratory Study

Rationale

Recent reports have shown increased cannabis use among women, leading to growing concerns about cannabis use disorder (CUD). Some evidence suggests a faster progression to addiction in women, known as the "telescoping effect." While there is preclinical evidence suggesting biological sex influences cannabinoid effects, human research remains scant. We investigated sex differences in the response to oral tetrahydrocannabinol (THC) in humans.

Methods

56 healthy men and women with prior exposure to cannabis but no history of CUD participated in a randomized, placebo-controlled, human laboratory study where they received a single 10 mg dose of oral THC (dronabinol). Subjective psychoactive effects were assessed by the visual analog scale of "high", psychotomimetic effects by the Clinician-Administered Dissociative Symptoms Scale and Psychotomimetic States Inventory, verbal learning and memory by Rey Auditory Verbal Learning Test (RAVLT), and physiological effects by heart rate. Outcomes were regularly measured on the test day, except for the RAVLT, which was assessed once. Peak differences from baseline were analyzed using a nonparametric method for repeated measures.

Results

Oral THC demonstrated significant dose-related effects in psychotomimetic and physiological domains, but not in RAVLT outcomes. A notable interaction between THC dose and sex emerged concerning the subjective "high" scores, with women reporting heightened sensations (p=0.05). No other significant effects of sex and THC dose interaction were observed.

Conclusion

Oral THC yields similar psychotomimetic and physiological effects across sexes, but women may experience a pronounced subjective psychoactive effect. Further research is needed to identify individual vulnerabilities and facilitate tailored interventions addressing CUD.

Understanding the Placental Biology of Tobacco Smoke, Nicotine, and Marijuana (THC) Exposures During Pregnancy

Widespread public health campaigns have reduces the prevalence of tobacco and nicotine exposures during pregnancy in the United States. However, tobacco and nicotine exposures during pregnancy persist as a common modifiable perinatal risk exposure. Furthermore, declines in tobacco use have been accompanied by parallel rises in both the prevalence and incidence of marijuana use in pregnancy. This is worrisome, as the macromolecules which comprise tobacco and marijuana smoke affect placental function. In this chapter we summarize the decades of evidence contributing to our understanding of the placental molecular pathophysiology accompanying these chemical exposures, thereby rendering risk of adverse perinatal outcomes.

Effects of Delta-9 Tetrahydrocannabinol (THC) on Oocyte Competence and Early Embryonic Development

Recent changes in legal status and public perception of cannabis have contributed to an increase use amongst women of reproductive age. Concurrently, there is inadequate evidence-based knowledge to guide clinical practice regarding cannabis and its effects on fertility and early embryonic development. This study aimed to evaluate the effects of the primary psychoactive component of cannabis, delta-9 tetrahydrocannabinol (THC), during oocyte maturation, and its impact on the developing embryo. Bovine oocytes were matured in vitro for 24 h under clinically relevant doses of THC mimicking plasma levels achieved after therapeutic (0.032 μM) and recreational (0.32 and 3.2 μM) cannabis use. THC-treated oocytes were assessed for development and quality parameters at both the oocyte and embryo level. Characteristics of oocytes treated with cannabinoid receptor antagonists were also assessed. Oocytes treated with 0.32 and 3.2 μM THC, were significantly less likely to reach metaphase II (p < 0.01) and consequently had lower cleavage rates at day 2 post-fertilization (p < 0.0001). Treatment with cannabinoid receptor antagonists restored this effect (p < 0.05). Oocytes that did reach MII showed no differences in spindle morphology. Oocytes treated with 0.032 μM THC had significantly lower connexin mRNA (p < 0.05) (correlated with decreased quality), but this was not confirmed at the protein level. At the blastocyst stage there were no significant differences in developmental rates or the proportion of trophectoderm to inner cell mass cells between the control and treatment groups. These blastocysts, however, displayed an increased level of apoptosis in the 0.32 and 3.2 μM groups (p < 0.0001). Our findings suggest a possible disruptive effect of cannabis on oocyte maturation and early embryonic development.

Cannabis use during pregnancy: Pharmacokinetics and effects on child development

The broad-based legalization of cannabis use has created a strong need to understand its impact on human health and behavior. The risks that may be associated with cannabis use, particularly for sensitive subgroups such as pregnant women, are difficult to define because of a paucity of dose-response data and the recent increase in cannabis potency. Although there is a large body of evidence detailing the mode of action of Δ⁹-tetrahydrocannabinol (THC) in adults, little work has focused on understanding how cannabis use during pregnancy may impact the development of the fetal nervous system and whether additional plant-derived cannabinoids might participate. This manuscript presents an overview of the historical and contemporary literature focused on the mode of action of THC in the developing brain, comparative pharmacokinetics in both pregnant and nonpregnant model systems and neurodevelopmental outcomes in exposed offspring. Despite growing public health significance, pharmacokinetic studies of THC have focused on nonpregnant adult subjects and there are few published reports on disposition parameters during pregnancy. Data from preclinical species show that THC readily crosses the placenta although fetal exposures appear lower than maternal exposures. The neurodevelopmental data in humans and animals suggest that prenatal exposure to THC may lead to subtle, persistent changes in targeted aspects of higher-level cognition and psychological well-being. There is an urgent need for well-controlled studies in humans and preclinical models on THC as a developmental neurotoxicant. Until more information is available, pregnant women should not assume that using cannabis during pregnancy is safe.

Sewer epidemiology mass balances for assessing the illicit use of methamphetamine, amphetamine and tetrahydrocannabinol

In sewer epidemiology, mass balances are used to back-extrapolate measurements of wastewater influent concentrations of appropriate drug residues to assess the parent illicit drug's level of use in upstream populations. This study focussed on developing and refining mass balances for the use of illicit methamphetamine, amphetamine and tetrahydrocannabinol. As a first step, a multi-criteria evaluation was used to select unchanged methamphetamine, unchanged amphetamine and 11-nor-9-carboxy-tetrahydrocannabinol as the most appropriate drug residues to track a selected population's use of illicit methamphetamine, amphetamine and tetrahydrocannabinol, respectively. For each of these selected drug residues, mass balances were developed by utilizing all disposition data available for their release from all their respective sources, incorporating route-of-administration considerations where relevant, and accounting for variations in the metabolic capacity of users of the various relevant licit and illicit sources. Further, since the selected drug residues for the use of methamphetamine and amphetamine cannot only result from their use but numerous other licit and illicit sources, comprehensive general source models were developed for their enantiomeric-specific release to sewers. The relative importance of the sources identified in the general source model was evaluated by performing national substance flow analyses for a number of countries. Results suggested that licit sources of methamphetamine are expected to be only of significance in populations where its illicit use is minor. Similarly, in populations where the use of illicitly produced amphetamine is currently of relevance, licit contributions to the sewer loads of amphetamine are likely to be of negligible importance. Lastly, the study of tetrahydrocannabinol back-extrapolation mass balances suggested that further research is required to assess the importance of fecal elimination of 11-nor-9-carboxy-tetrahydrocannabinol.

Health consequences of acute and chronic marihuana use

Chemical content, assay procedures, and pharmacokinetics of cannabis sativa are discussed briefly. Cannabinoid cellular effects relating to chromosomes and immunity including cellular metabolism and allergic reactions are presented. Gross and microscopic brain pathology due to cannabis use is reviewed involving EEG alterations, psychopathology including aggressive behaviour as well as properties of psychomotor impairment, tolerance and dependence. Cardiopulmonary effects of marihuana are recorded under pulmonary pharmacological effects including the macrophage defense system and effects of smoke constituents; under cardiovascular effects cardiac toxicity and possible mechanism of action are discussed. Alterations of reproductive hormonal production and maturation of reproductive cells by marihuana in males and females with attendant impairment of reproductive function or fertility including reproductive outcome are reported. Field studies with healthy chronic cannabis users in Jamaica, Greece and Costa Rica are related as to observed medical alterations. Potential clinical effects are summarized in point form.

Pharmacology of some synthetic tetrahydrocannabinols

DMHP (1-hydroxy-3-1', 2'-dimethylheptyl-6,6,9-trimethyl 7,8,9,10-tetrahydro-6-dibenzopyran or in brief dimethyl heptyl pyran, EA 1476) is a synthetic analog of delta 9-tetrahydrocannabinol (delta 9-THC). Both DMHP and its acetate, DMHPA (EA 2233) produce varying degrees of physical and mental incapacitation. Both compounds elicit orthostatic hypotension at dose levels far below those required to produce mild mental incapacitation. Compared with delta 9-THC, DMHP has clearly more potent and prolonged hypotensive action, but much less psychological effect. The potencies of DMHP and DMHPA are more or less similar, but the acetate derivative is more stable against the degrading effects of light and air. Like DMHP, DMHPA consists of eight isomers which vary in their potency. Accordingly, depending on the proportion of the isomers, the racemic mixtures show variability in their potencies. The isomers 2 and 4 have been shown to be more potent than the other isomers.

Penetration of delta-9-tetrahydrocannabinol and 11-OH-delta-9-tetrahydrocannabinol through the blood-brain barrier

The relative brain uptake (extraction into brain) of delta-9-tetrahydrocannabinol (delta-9-THC) and the primary metabolite 11-OH-delta-9-tetrahydrocannabinol (11-OH-delta-9-THC) was measured after close intracarotid injection in rats of radiolabelled moities using labelled antipyrine as reference. The extraction percentage was of the same magnitude when injections were given in saline, 66 +/- 11% and 70 +/- 9% respectively after 5 sec., 59 +/- 4 and 67 +/- 8 respectively after 15 sec. While the extraction of 11-OH-delta-9-THC was the same when injected into plasma, the extraction of delta-9-THC was only about half of the extraction from saline, and also half the extraction of the metabolite from plasma. The higher uptake quantity of the metabolite into the brain may account for the relatively greater effect on the central nervous system of the metabolite than of the parent compound at equal concentrations in plasma. Moreover our experiments demonstrate that 11-OH-delta-THC formed in the liver after cannabis (delta-9-THC) administration may exert significant brain effects.

Pharmacokinetics of delta9-tetrahydrocannabinol in dogs

The pharmacokinetics of intravenously administered 14C-delta9-tetrahydrocannabinol and derived radiolabeled metabolites were studied in three dogs at two doses each at 0.1 or 0.5 and 2.0 mg/kg. Two dogs were biliary cannulated; total bile was collected in one and sampled in the other. The time course for the fraction of the dose per milliliter of plasma was best fit by a sum of five exponentials, and there was no dose dependency. No drug was excreted unchanged. The mean apparent volume of distribution of the central compartment referenced to total drug concentration in the plasma was 1.31 +/- 0.07 liters, approximately the plasma volume, due to the high protein binding of 97%. The mean metabolic clearance of drug in the plasma was 124 +/- 3.8 ml/min, half of the hepatic plasma flow, but was 4131 +/- 690 ml/min referenced to unbound drug concentration in the plasma, 16.5 times the hepatic plasma flow, indicating that net metabolism of both bound and unbound drug occurs. Apparent parallel production of several metabolites occurred, but the pharmacokinetics of their appearance were undoubtedly due to their sequential production during liver passage. The apparent half-life of the metabolic process was 6.9 +/- 0.3 min. The terminal half-life of delta9-tetrahydrocannabinol in the pseudo-steady state after equilibration in an apparent overall volume of distribtuion of 2170 +/- 555 liters referenced to total plasma concentration was 8.2 +/- 0.23 days, based on the consistency of all pharmacokinetic data. The best estimate of the terminal half-life, based only on the 7000 min that plasma levels could be monitored with the existing analytical sensitivity, was 1.24 days. However, this value was inconsistent with the metabolite production and excretion of 40-45% of dose in feces, 14-16.5% in urine, and 55% in bile within 5 days when 24% of the dose was unmetabolized and in the tissue at that time. These data were consistent with an enterohepatic recirculation of 10-15% of the metabolites. Intravenously administered radiolabeled metabolites were totally and rapidly eliminated in both bile and urine; 88% of the dose in 300 min with an apparent overall volume of distribution of 6 liters. These facts supported the proposition that the return of delta9-tetrahydrocannabinol from tissue was the rate-determining process of drug elimination after initial fast distribution and metabolism and was inconsistent with the capability of enzyme induction to change the terminal half-life.

Aspects of tolerance to and dependence on cannabis

Tolerance at all levels of complexity in the brain involves "learning" in the sense of the acquisition of compensatory adaptations to the consequences of the presence of a drug-produced disturbance in function. Depending on the function, species, and dose of cannabis, "tissue tolerance," behaviorally augmented (to provide the presence of the disturbed function) or not, develops at different rates or not all (e.g., to impairment of the logical sequence of thoughts, to which no tolerance has yet been demonstrated). "Dispositional tolerance" (increased rate of metabolism of delta 9-THC due to enzyme induction) may play a role in the development of tolerance or "reverse tolerance" to cannabis in man. There is evidence that for the label "high," placebo effects may account for the "reverse tolerance" seen in experienced users on smoking (but not on ingestion of delta 9-THC or placebo) along with evidence of residual tolerance to other not-so-labeled effects of the drug. Dependence on cannabis, in the sense of abstinence phenomena on abrupt withdrawal of delta 9-THC, has been demonstrated in monkeys made tolerant to delta 9-THC given four times daily for about 1 month. In man, physiologic marijuana abstinence signs have not been demonstrated, but behavioral (and some physiologic) abstinence phenomena have been reported in heavy users of hashish or ganja. The between-dose hyperirritability and dysphoria reported to occur in experimental studies on chronic marijuana intoxication may actually be early and short-lived abstinence changes. In the West, where marijuana with relatively low delta 9-THC content is widely smoked, dependence in the sense of drug-seeking behavior appears to be less a function of any pharmacologic reinforcing properties the drug may have than of secondary (conditioned) reinforcement derived from the social milieu in which the marijuana is smoked. In cultures where marijuana of higher delta 9-THC content, hashish, or ganja is used, pharmacologic reinforcement (through suppression of abstinence changes) may play a greater role in maintaining drug-seeking behavior.

A test of state dependency effects in marihuana intoxication for the learning of psychomotor tasks

Cannabis cigarettes calibrated to deliver 7 mg delta9-THC were administered to experienced cannabis users and to novices in a 2 x 2 state-dependency learning design using psychomotor tasks. Subjects given four training sessions under marihuana performed no better on the fifth (test) session with the drug than those subjects who had trained in the non-drug condition and were tested in the drug condition. Cannabis-induced impairment in the performance of these tasks is such that prior training in the non-drug condition appears to confer no advantage to the subject. There was no evidence of state-dependency effects in psychomotor performance between drug and non-drug conditions.

Plasma protein binding of 7-hydroxy- 1-tetrahydrocannabinol: an active 1-tetrahydrocannabinol metabolite

7-Hydroxy-Δ1-tetrahydrocannabinol, which is a pharmacologically and psychologically active metabolite of Δ1-tetrahydrocannabinol in man, has been shown by equilibrium dialysis and ultrafiltration to be bound 94–99% to plasma proteins. Further experiments, using the [14C]labelled compound, with agarose and Polyacrylamide gel electrophoresis and ultracentrifugation suggest that albumin, α1-lipoprotein and, to a minor degree, also β-lipoprotein are involved in the protein binding of 7-hydroxy-Δ1-tetrahydrocannabinol in blood plasma.

11-hydroxy- 9 -tetrahydrocannabinol: pharmacology, disposition, and metabolism of a major metabolite of marihuana in man

11-Hydroxy-Delta(9)-tetrahydrocannabinol, administered intravenously to man, produces psychologic and pharmacologic effects that persist for several hours. The drug and its metabolites are excreted in urine and feces for more than 1 week. The pharmacology, disposition, and metabolism of 11-hydroxy-Delta(9)-tetra-hydrocannabinol mimic that of Delta(9)-tetrahydrocannabinol, thus providing evidence that Delta(9)-tetrahydrocannabinol (the major active component of marihuana) is converted to the 11-hydroxy compound in man, the latter compound being responsible for the effects.