Terminal elimination plasma half-life of delta 1-tetrahydrocannabinol (delta 1-THC) in heavy users of marijuana

A two-sample approach to retrograde extrapolation of blood THC concentrations - Is it feasible?

BACKGROUND

Retrograde extrapolation of drug concentrations in blood can be relevant in cases of drug-impaired driving and is regularly used in forensic toxicology in Norway. Δ9-tetrahydrocannabinol (THC) has complex, multi-compartmental pharmacokinetics, which makes retrograde extrapolation of blood THC concentrations problematic. In the present study, we evaluated an approach to retrograde extrapolation in which momentary rates of decrease of THC were estimated from two consecutive blood samples in apprehended drivers.

MATERIAL AND METHODS

Data were collected from apprehended drivers in Norway 2000-2020. We included 548 cases in which THC was detected in two consecutive blood samples collected ≥ 20 min apart. THC concentrations were measured by GC-MS and UHPLC-MS/MS. In each case, THC concentrations and the time between the two sampling points (Δt) were used to estimate the rate constant k. The relationship between THC concentration and k was modelled by linear regression.

RESULTS

The median Δt was 31 min (interquartile range, IQR = 9). The median blood THC concentration was 2.4 μg/L (IQR = 3.4) at the first sampling point and 2.3 μg/L (IQR =3.1) at the second. The concentration decreased in 62% and increased in 38% of all cases. However, considering measurement uncertainty, the changes were not statistically significant in 87% of cases. The mean of k was 0.12 h-1, corresponding to an apparent t1/2 of 6.0 h. The t1/2 predicted from linear regression of k against THC concentration ranged from 0.93 to 13 h for the highest and lowest concentrations observed (36 and 0.63 μg/L, respectively). The time from driving to blood collection had a median of 1.7 h (IQR = 1.5), and did not correlate with k.

CONCLUSIONS

The apparent t1/2 of THC calculated from the mean of k was 6.0 h, which is shorter than the terminal elimination t1/2 suggested in previous population studies. This indicates that blood samples were often taken during the late distribution phase of THC. Because Δt was short relative to the rates of decrease expected in the late distribution and elimination phases, the underlying true concentration changes related to in vivo pharmacokinetics were small and masked by the relatively larger "false" changes introduced by random analytical and pre-analytical error. Therefore, individual values of k calculated from only two blood samples taken a short time apart are unreliable, and a two-sample approach to retrograde extrapolation of THC cannot be recommended.

How long does a single oral dose of cannabidiol persist in plasma? Findings from three clinical trials

A growing number of clinical trials (CTs) are investigating the therapeutic potential of cannabidiol (CBD), a non-intoxicating phytocannabinoid found in Cannabis sativa. These CTs often use crossover experimental designs requiring 'washout' (clearance) periods. However, the length of time CBD persists in plasma (its 'window of detection') is unclear and could be significant. Indeed, the structurally related phytocannabinoid, Δ⁹ -tetrahydrocannabinol (THC), has a long window of detection in plasma. We investigated the extent to which CBD and its major metabolites persist in plasma. Data from three CTs that measured plasma cannabinoid concentrations ≥7 days after administering a single oral dose of CBD were pooled. The CBD doses were as follows: CT #1: 300 mg; CT #2: 200 mg (and 10 mg THC); and CT #3: 15, 300 and 1500 mg (one per treatment session). Thirty-two participants were included in the analysis, 17 of whom (from CT #3) provided repeated measures. Overall, 0% (15 mg), 60% (200 mg), 28% (300 mg) and 100% (1500 mg) of participants had detectable concentrations (i.e., >0.25 ng·ml^-1 ) of CBD in plasma ≥7 days post-treatment (some, several weeks post-treatment). A zero-inflated negative binomial mixed-effects regression analysis (R² _m  = 0.44; R² _c  = 0.73) predicted that, on average, a 13 day washout period would reduce plasma CBD concentrations to 'zero' (i.e., <0.25 ng·ml^-1 ) if a single oral dose of 300 mg was consumed. Higher doses require longer washout periods; concomitant medications may also affect clearance. In conclusion, CBD has a long window of detection in plasma. Crossover studies involving CBD should, therefore, be conducted with caution, particularly when higher doses and/or chronic dosing regimens are used.

Cannabidiol (CBD) Dosing: Plasma Pharmacokinetics and Effects on Accumulation in Skeletal Muscle, Liver and Adipose Tissue

Oral cannabidiol (CBD) consumption is widespread in North America and Europe, as it has analgesic, neuroprotective and antitumor effects. Although oral CBD consumption in humans affords beneficial effects in epileptic and inflammatory states, its pharmacokinetics and subsequent uptake into tissue are largely unknown. This study investigated plasma pharmacokinetics and accumulation of CBD in gastrocnemius muscle, liver and adipose tissue in adult rats following oral gavage. CBD was fed relative to body mass at 0 (control), 30, 115, or 230 mg/Kg/day for 28 days; with 6 males and 6 females per dosing group. Pharmacokinetics were assessed on day 1 and day 28 in the group receiving CBD at 115 mg/Kg/day. The rise in tissue CBD was closely related to specific pharmacokinetic parameters, and adipose tissue levels were ~10 to ~100 fold greater than liver or muscle. Tissue CBD levels were moderately correlated between adipose and muscle, and adipose and liver, but were highly correlated for liver and muscle. CBD feeding resulted in several gender-specific effects, including changes in pharmacokinetics, relationships between pharmacokinetic parameters and tissue CBD and differences in tissue CBD levels. CBD accumulation in mammalian tissues has the potential to influence receptor binding and metabolism; therefore, the present findings may have relevance for developing oral dosing regimens.

Pharmacokinetic Evaluation of a Cannabidiol Supplement in Horses

Cannabidiol (CBD) products have gained popularity among horse owners despite limited evidence regarding pharmacokinetics. The purpose of this study was to describe the pharmacokinetic profile of multiple doses of an orally administered cannabidiol product formulated specifically for horses. A randomized 2-way crossover design was used. Seven horses received 0.35 or 2.0 mg/kg CBD per os every 24 hours for 7 total doses, separated by a 2-week washout. Plasma CBD and delta-9-tetrahydrocannabinol (THC) were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) daily through day 10, then on day 14 after beginning CBD administration. On the final day of CDB administration, plasma CBD and THC were quantified at multiple times. After administration of 0.35 mg/kg of CDB, the C_max of CBD was 6.6 ± 2.1 ng/mL while T_max was 1.8 ± 1.2 hour, whereas the C_max for THC was 0.7 ± 0.6 ng/mL with a T_max of 2.5 ± 1 hour. After administration of 2.0 mg/kg of CBD, the C_max of CBD was 51 ± 14 ng/mL with a mean T_max of 2.4 ± 1.1 hour and terminal phase half-life of 10.4 ± 6 hour, whereas the C_max of THC was 7.5 ± 2.2 ng/mL with a T_max of 2.9 ± 1.1 hour. Oral administration of a cannabidiol product at 0.35 mg/kg or 2.0 mg/kg once daily for 7 days was well-tolerated. Based on plasma CBD levels obtained, dose escalation trials in the horse evaluating clinical efficacy at higher mg/kg dose rates are indicated.

Cannabis and Cannabis Edibles: A Review

Cannabis is an excellent natural source of fiber and various bioactive cannabinoids. So far, at least 120 cannabinoids have been identified, and more novel cannabinoids are gradually being unveiled by detailed cannabis studies. However, cannabinoids in both natural and isolated forms are especially vulnerable to oxygen, heat, and light. Therefore, a diversity of cannabinoids is associated with their chemical instability to a large extent. The research status of structural conversion of cannabinoids is introduced. On the other hand, the use of drug-type cannabis and the phytocannabinoids thereof has been rapidly popularized and plays an indispensable role in both medical therapy and daily recreation. The recent legalization of edible cannabis further extends its application into the food industry. The varieties of legal edible cannabis products in the current commercial market are relatively monotonous due to rigorous restrictions under the framework of Cannabis Regulations and infancy of novel developments. Meanwhile, patents/studies related to the safety and quality assurance systems of cannabis edibles are still rare and need to be developed. Furthermore, along with cannabinoids, many phytochemicals such as flavonoids, lignans, terpenoids, and polysaccharides exist in the cannabis matrix, and these may exhibit prebiotic/probiotic properties and improve the composition of the gut microbiome. During metabolism and excretion, the bioactive phytochemicals of cannabis, mostly the cannabinoids, may be structurally modified during enterohepatic detoxification and gut fermentation. However, the potential adverse effects of both acute and chronic exposure to cannabinoids and their vulnerable groups have been clearly recognized. Therefore, a comprehensive understanding of the chemistry, metabolism, toxicity, commercialization, and regulations regarding cannabinoid edibles is reviewed and updated in this contribution.

THC detection in the breath

Cannabis legalization and common use has further driven the need for accurate THC detection and analysis for roadside testing. While reliable and accurate techniques, such as mass spectrometry (MS) exist for the analysis of THC, the market lacks technologies that are portable and can be utilized outside of a laboratory setting. Innovations utilizing unique technologies have steadily been increasing. These include carbon nanotubes, specifically semiconductor-enriched single-walled carbon nanotube (s-SWCNT) chemiresistors and carbon nanotubes with integrated molecularly imprinted polymers (MIPs), giant magnetoresistive (GMR) biosensors, capillary electrophoresis (CE) with ultraviolet light-emitting diode-induced native fluorescence (UV-LEDIF), and electrochemical detection with the use of screen printed carbon electrodes and N-(4-amino-3-methoxyphenyl)-methanesulfonamide. Finally, a novel device has been recently launched to detect THC in the breath with the use of TLC and fluorescent probes. This review highlights the technologies that have been, and are being, explored to ultimately lead to a portable road-side test for THC once further testing in practice has been completed.

Clinical Pharmacokinetics of Cannabinoids and Potential Drug-Drug Interactions

Over the past few years, considerable attention has focused on cannabidiol (CBD) and Δ⁹-tetrahydrocannabinol (THC), the two major constituents of Cannabis sativa, mainly due to the promising potential medical uses they have shown. However, more information on the fate of these cannabinoids in human subjects is still needed and there is limited research on the pharmacokinetic drug-drug interactions that can occur in the clinical setting and their prevalence. As the use of cannabinoids is substantially increasing for many indications and they are not the first-line therapy in any treatment, health care professionals must be aware of drug-drug interactions during their use as serious adverse events can happen related with toxic or ineffective outcomes. The present chapter overview summarizes our current knowledge on the pharmacokinetics and metabolic fate of CBD and THC in humans and discusses relevant drug-drug interactions, giving a plausible explanation to facilitate further research in the area.

[Cannabis: Similarities and differences with tobacco]

Nicotine is the specific psychoactive substance of tobacco while tetrahydrocannabinol (THC) is the specific component of cannabis. The inhalation technique of cannabis is different from that of tobacco smoking: the volume of puffs is larger, inhalation is deeper, and pulmonary retention time is longer. Cannabis addiction is difficult to evaluate, both products often being smoked concomitantly. The principle physical side effects of cannabis affect organs and functions in a similar way to tobacco: pulmonary, cardiovascular, endocrine and stomatological. Gastrointestinal complications such as cannabinoid hyperemesis are specific to cannabis. Some psychological effects of THC may be acute (altered time and space perception, sensory disability, decreased vigilance, mood and dissociative disorders, hallucinations and delirium, impaired learning and memory, impaired cognitive and motor performance, panic attacks and anxiety) or chronic (lack of motivation, disorganisation of thoughts, increase in frequency and severity of schizophrenic crises). Cannabis can also be implicated in traffic and workplace accidents. Synthetic cannabinoids have increased psychotropic and somatic effects due to a greater affinity for brain cannabinoid receptors.

Delta-9 THC can be detected and quantified in the semen of men who are chronic users of inhaled cannabis

PURPOSE

The purpose of this proof-of-concept study was to determine whether delta-9-tetrahydrocannabinol (THC) and THC metabolites (11-OH THC and THC-COOH) can be detected in semen.

METHODS

Twelve healthy men aged 18-45 years who identified as chronic and heavy users of inhaled cannabis were recruited. THC and THC metabolite levels were measured in serum, urine, and semen of the participants. Semen analyses were performed. Serum reproductive hormones were measured.

RESULTS

The median age and BMI of participants were 27.0 years and 24.7 kg/m², respectively. Over half the participants were daily users of cannabis for over 5 years. Serum reproductive hormones were generally within normal ranges, except prolactin, which was elevated in 6 of 12 participants (mean 13.9 ng/mL). The median sperm concentration, motility, and morphology were 75.5 million/mL, 69.5%, and 5.5%, respectively. Urinary THC-COOH was detected in all 12 participants, and at least one serum THC metabolite was present in 10 of 12 participants. Two semen samples had insufficient volume to be analyzed. THC was above the reporting level of 0.50 ng/mL in the semen of two of the remaining participants. Seminal THC was moderately correlated with serum levels of THC (r = 0.66), serum 11-OH THC (r = 0.57), and serum THC-COOH (r = 0.67). Seminal delta-9 THC was not correlated with urinary cannabinoid levels or semen analysis parameters.

CONCLUSION

This is the first study to identify and quantify THC in human semen, demonstrating that THC can cross the blood-testis barrier in certain individuals. Seminal THC was found to be moderately correlated with serum THC and THC metabolites.

Δ9-tetrahydrocannabinol (THC) is present in the body between smoking sessions in occasional non-daily cannabis users

BACKGROUND

THC can be measured in blood up to a month after last intake in heavy cannabis users. The cognitive deficits during abstinence have been hypothesized to be at least in part due to residual THC in brain. To which extent THC accumulation will occur after occasional cannabis use has gained limited attention. We aimed to predict THC-levels between smoking sessions in non-daily as well as daily cannabis users and to compare these predictions with published THC levels.

METHODS

Predictions were based on pharmacokinetic principles on drug accumulation after repeated dosing, applied to different cannabis smoking patterns, using data from a three-compartment model for THC pharmacokinetics and results on the terminal elimination half-life of THC in humans. We searched the literature for THC measurements which could be compared with these predictions. We found no such results from controlled studies of long-term repeated cannabis consumption of known THC amounts. Thirteen published studies contained, however, enough information on cannabis use and results from THC-measurements to make tentative comparisons with the predictions.

RESULTS

The predictions of THC-plasma levels present after different cannabis smoking patterns assuming terminal elimination half-lives of THC of 21.5 h or longer, had some support in published THC levels measured in individuals self-reporting their cannabis consumption. We found no consistent discrepancies between the predictions and reported THC plasma levels after non-daily or daily cannabis use. The predictions indicate that THC might be present in plasma between smoking sessions above usual analytical limits when smoking every third and second day, and at lower levels after once weekly smoking.

CONCLUSIONS

The study indicates that THC might be present continuously even in non-daily smokers at low levels, even if the smoking occasions are separated by a week. This is different from alcohol, where ethanol has disappeared after a day. From a toxicological point of view the persistance of THC in the brain, raises questions whether this should be given more attention as with other toxicological thinking where long-term presence of bioactive substances gives rise to concern. There are some uncertainties in this analysis, and controlled studies on THC-accumulation accompanying different use patterns seem warranted.

A marijuana-drug interaction primer: Precipitants, pharmacology, and pharmacokinetics

In the United States, the evolving landscape of state-legal marijuana use for recreational and/or medical purposes has given rise to flourishing markets for marijuana and derivative products. The popularity of these products highlights the relative absence of safety, pharmacokinetic, and drug interaction data for marijuana and its constituents, most notably the cannabinoids. This review articulates current issues surrounding marijuana terminology, taxonomy, and dosing; summarizes cannabinoid pharmacology and pharmacokinetics; and assesses the drug interaction risks associated with co-consuming marijuana with conventional medications. Existing pharmacokinetic data are currently insufficient to fully characterize potential drug interactions precipitated by marijuana constituents. As such, increasing awareness among researchers, clinicians, and federal agencies regarding the need to conduct well-designed in vitro and clinical studies is imperative. Mechanisms that help researchers navigate the legal and regulatory barriers to conducting these studies would promote rigorous evaluation of potential marijuana-drug interactions and inform health care providers and consumers about the possible risks of co-consuming marijuana products with conventional medications.

The pitfalls of per se thresholds in accurately identifying acute cannabis intoxication at autopsy

Some laws in the United States define cannabis-impaired driving criteria using various per se language that uses specific concentrations of various cannabinoid compounds to establish driving-under-the-influence (DUI). We hypothesize that there will be decedents whose postmortem toxicology profiles would be considered indicative of an acute cannabinoid intoxication under varying DUI per se laws, despite having survived longer than the expected duration of cannabinoid impairment effects. This study examined decedents in whom quantified cannabis metabolites were detected in Connecticut medical examiner autopsy samples, in which the medically-confined survival interval was longer (4-12 and > 12 h) than the expected duration of cannabinoid impairment effects. Several of the 15 decedents, despite being intubated and/or comatose during the medically-confined period of abstinence, would have exceeded DUI per se limits based upon their toxicology results. The use of drug concentrations alone to equate to an acute cannabis intoxication may result in inappropriate arrest, prosecution, and civil liability.

The pharmacokinetics and the pharmacodynamics of cannabinoids

There is increasing interest in the use of cannabinoids for disease and symptom management, but limited information available regarding their pharmacokinetics and pharmacodynamics to guide prescribers. Cannabis medicines contain a wide variety of chemical compounds, including the cannabinoids delta-9-tetrahydrocannabinol (THC), which is psychoactive, and the nonpsychoactive cannabidiol (CBD). Cannabis use is associated with both pathological and behavioural toxicity and, accordingly, is contraindicated in the context of significant psychiatric, cardiovascular, renal or hepatic illness. The pharmacokinetics of cannabinoids and the effects observed depend on the formulation and route of administration, which should be tailored to individual patient requirements. As both THC and CBD are hepatically metabolized, the potential exists for pharmacokinetic drug interactions via inhibition or induction of enzymes or transporters. An important example is the CBD-mediated inhibition of clobazam metabolism. Pharmacodynamic interactions may occur if cannabis is administered with other central nervous system depressant drugs, and cardiac toxicity may occur via additive hypertension and tachycardia with sympathomimetic agents. More vulnerable populations, such as older patients, may benefit from the potential symptomatic and palliative benefits of cannabinoids but are at increased risk of adverse effects. The limited availability of applicable pharmacokinetic and pharmacodynamic information highlights the need to initiate prescribing cannabis medicines using a 'start low and go slow' approach, carefully observing the patient for desired and adverse effects. Further clinical studies in the actual patient populations for whom prescribing may be considered are needed, to derive a better understanding of these drugs and enhance safe and optimal prescribing.

Relating Observed Psychoactive Effects to the Plasma Concentrations of Delta-9-Tetrahydrocannabinol and Its Active Metabolite: An Effect-Compartment Modeling Approach

The medical use of marijuana is increasing, yet little is known about the exposure-response relationship for its psychoactive effects. It is well known that the plasma concentrations of the principal psychoactive component of marijuana, Δ⁹-tetrahydrocannabinol (THC), do not directly correlate to the observed psychoactive effects. The purpose of this research was to use an effect-compartment modeling approach to predict and relate the concentrations of the psychoactive components (THC and its active metabolite) in the "hypothetical" effect-site compartment to the observed psychoactive effects. A "hypothetical" effect-compartment model was developed using literature data to characterize the observed delay in peak "highness" ratings compared with plasma concentrations of the psychoactive agents following intravenous administration of THC. A direct relationship was established between the reported psychoactive effects ("highness" or intoxication) and the predicted effect-site concentrations of THC. The differences between estimated equilibration half-lives for THC and THC-OH in the effect-compartment model indicated the differential equilibration of parent drug and the active metabolite between plasma and the effect-site. These models contribute to the understanding of the pharmacokinetic-pharmacodynamic relationships associated with marijuana use and are important steps in the prediction of pharmacodynamic effects related to the psychoactive components in marijuana.

Survey of cannabis use in patients with amyotrophic lateral sclerosis

Cannabis (marijuana) has been proposed as treatment for a widening spectrum of medical conditions and has many properties that may be applicable to the management of amyotrophic lateral sclerosis (ALS). This study is the first, anonymous survey of persons with ALS regarding the use of cannabis. There were 131 respondents, 13 of whom reported using cannabis in the last 12 months. Although the small number of people with ALS that reported using cannabis limits the interpretation of the survey findings, the results indicate that cannabis may be moderately effective at reducing symptoms of appetite loss, depression, pain, spasticity, and drooling. Cannabis was reported ineffective in reducing difficulties with speech and swallowing, and sexual dysfunction. The longest relief was reported for depression (approximately two to three hours).

Comparison of cannabinoids in hair with self-reported cannabis consumption in heavy, light and non-cannabis users

Introduction

Biological tests of drug use can be used to inform clinical and legal decisions and hold potential to provide evidence for epidemiological studies where self‐reported behaviour may be unavailable or unreliable. We test whether hair can be considered as a reliable marker of cannabis exposure.

Methods

Hair samples were collected from 136 subjects who were self‐reported heavy, light or non‐users of cannabis and tested using GC‐MS/MS. Sensitivity, specificity, positive predictive value and negative predictive value were calculated for five cannabinoids (tetrahydrocannabinol [THC], THC‐OH, THC‐COOH, cannabinol and cannabidiol). Samples also were segmented in 1 cm sections representing 1 month exposure and the correlation between amount of cannabinoid detected and self‐reported cannabis consumption tested.

Results

All five cannabinoids were detected. Seventy‐seven percent of heavy users, 39% of light users and 0% of non‐users tested positive for THC. The sensitivity of detection of THC was 0.77 (0.56–0.91) comparing heavy cannabis smokers with light and non‐users, whereas the sensitivity of other cannabinoids generally was considerably lower. The positive and negative predictive value of detection of THC were 0.57 (0.39–0.74) and 0.91 (0.82–0.97), respectively. A correlation of 0.52 (P < 0.001) was observed between self‐reported monthly cannabis use and THC.

Discussion

Hair analysis can be used as a qualitative indicator of heavy (daily or near daily) cannabis consumption within the past 3 months. However, this approach is unable to reliably detect light cannabis consumption or determine the quantity of cannabis used by the individual. [Taylor M, Lees R, Henderson G, Lingford‐Hughes A, Macleod J, Sullivan J, Hickman M. Comparison of cannabinoids in hair with self‐reported cannabis consumption in heavy, light and non‐cannabis users. Drug Alcohol Rev 2017;36:220‐226]

Metabolomics of Δ9-tetrahydrocannabinol: implications in toxicity

Cannabis sativa is the most commonly used recreational drug, Δ(9)-tetrahydrocannabinol (Δ(9)-THC) being the main addictive compound. Biotransformation of cannabinoids is an important field of xenobiochemistry and toxicology and the study of the metabolism can lead to the discovery of new compounds, unknown metabolites with unique structures and new therapeutic effects. The pharmacokinetics of Δ(9)-THC is dependent on multiple factors such as physical/chemical form, route of administration, genetics, and concurrent consumption of alcohol. This review aims to discuss metabolomics of Δ(9)-THC, namely by presenting all known metabolites of Δ(9)-THC described both in vitro and in vivo, and their roles in the Δ(9)-THC-mediated toxic effects. Since medicinal use is increasing, metabolomics of Δ(9)-THC will also be discussed in order to uncover potential active metabolites that can be made available for this purpose.

Abstinence phenomena of chronic cannabis-addicts prospectively monitored during controlled inpatient detoxification: cannabis withdrawal syndrome and its correlation with delta-9-tetrahydrocannabinol and -metabolites in serum

OBJECTIVE

To investigate the course of cannabis withdrawal syndrome (CWS) within a controlled inpatient detoxification setting and to correlate severity of CWS with the serum-levels of delta-9-tetrahydrocannabinol (THC) and its main metabolites 11-hydroxy-delta-9-tetrahydrocannabinol (THC-OH) and 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH).

METHODS

Thirty-nine treatment-seeking chronic cannabis dependents (ICD-10) were studied on admission and on abstinent days 2, 4, 8 and 16, using a CWS-checklist (MWC) and the Clinical Global Impression-Severity scale (CGI-S). Simultaneously obtained serum was analysed to its concentration of THC, THC-OH and THC-COOH.

RESULTS

MWC peaked on day 4 (10.4 ± 4.6 from 39 points) and declined to 2.9 ± 2.4 points on day 16. Women had a significantly stronger CWS than men. The CWS was dominated by craving>restlessness>nervousness>sleeplessness. CGI-S peaked with 5 out of 7 points. On admission, THC and its metabolites did negatively correlate with the severity of CWS. There was no significant correlation afterwards, no matter if CWS was medicated or not. THC-OH in serum declined most rapidly below detection limit, on median at day 4. At abstinence day 16, the THC-levels of 28.2% of the patients were still above 1g/ml (range: 1.3 to 6.4 ng/ml).

CONCLUSIONS

CWS increased and then decreased without any correlation between its severity and the serum-levels of THC or its main metabolites after admission. According to the CGI-S, most patients achieved the condition of 'markedly ill'. Serum THC-OH was most clearly associated with recent cannabis use. Residual THC was found in the serum of almost one-third of the patients at abstinence day 16.

Recent advances in LC–MS/MS analysis of Δ9-tetrahydrocannabinol and its metabolites in biological matrices

Cannabis is the most widely used illicit drug in the world. The pharmacological properties of Δ9-tetrahydrocannabinol also make it a promising molecule in the treatment of different pathologies. Understanding the PKs and PDs of this drug requires the determination of the concentration of Δ9-tetrahydrocannabinol and metabolites in biological matrices. For this purpose many analytical methodologies using mass spectrometric detection have been developed. In recent years, LC–MS/MS has become the gold standard in analysis of tetrahydrocannabinol and its metabolites due to the high selectivity and sensitivity, but above all, due to the ability to determine free and conjugate analytes in one run.

In vitro stability of free and glucuronidated cannabinoids in blood and plasma following controlled smoked cannabis

BACKGROUND

Blood and plasma cannabinoid stability is important for test interpretation and is best studied in authentic rather than fortified samples.

METHODS

Low and high blood and plasma pools were created for each of 10 participants after they smoked a cannabis cigarette. The stabilities of Δ(9)-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), 11-nor-9-carboxy-THC (THCCOOH), cannabidiol (CBD), cannabinol (CBN), THC-glucuronide, and THCCOOH-glucuronide were determined after 1 week at room temperature; 1, 2, 4, 12, and 26 (±2) weeks at 4 °C; and 1, 2, 4, 12, 26 (±2), and 52 (±4) weeks at -20 °C. Stability was assessed by Friedman test.

RESULTS

Numbers of THC-glucuronide and CBD-positive blood samples were insufficient to assess stability. In blood, 11-OH-THC and CBN were stable for 1 week at room temperature, whereas THC and THCCOOH-glucuronide decreased and THCCOOH increased. In blood, THC, THCCOOH-glucuronide, THCCOOH, 11-OH-THC, and CBN were stable for 12, 4, 4, 12, and 26 weeks, respectively, at 4 °C and 12, 12, 26, 26, and 52 weeks at -20 °C. In plasma, THC-glucuronide, THC, CBN, and CBD were stable for 1 week at room temperature, whereas THCCOOH-glucuronide and 11-OH-THC decreased and THCCOOH increased. In plasma, THC-glucuronide, THC, THCCOOH-glucuronide, THCCOOH, 11-OH-THC, CBN, and CBD were stable for 26, 26, 2, 2, 26, 12, and 26 weeks, respectively, at 4 °C and 52, 52, 26, 26, 52, 52, and 52 weeks, respectively, at -20 °C.

CONCLUSIONS

Blood and plasma samples should be stored at -20 °C for no more than 3 and 6 months, respectively, to assure accurate cannabinoid quantitative results.

Short- and long-term cognitive effects of chronic cannabinoids administration in late-adolescence rats

The use of cannabis can impair cognitive function, especially short-term memory. A controversial question is whether long-term cannabis use during the late-adolescence period can cause irreversible deficits in higher brain function that persist after drug use stops. In order to examine the short- and long-term effects of chronic exposure to cannabinoids, rats were administered chronic i.p. treatment with the CB1/CB2 receptor agonist WIN55,212-2 (WIN; 1.2 mg/kg) for two weeks during the late adolescence period (post-natal days 45–60) and tested for behavioral and electrophysiological measures of cognitive performance 24 hrs, 10 and 30 days after the last drug injection. The impairing effects of chronic WIN on short-term memory in the water maze and the object recognition tasks as well as long-term potentiation (LTP) in the ventral subiculum (vSub)-nucleus accumbens (NAc) pathway were temporary as they lasted only 24 h or 10 d after withdrawal. However, chronic WIN significantly impaired hippocampal dependent short-term memory measured in the object location task 24 hrs, 10, 30, and 75 days after the last drug injection. Our findings suggest that some forms of hippocampal-dependent short-term memory are sensitive to chronic cannabinoid administration but other cognitive impairments are temporary and probably result from a residue of cannabinoids in the brain or acute withdrawal effects from cannabinoids. Understanding the effects of cannabinoids on cognitive function may provide us with tools to overcome these impairments and for cannabinoids to be more favorably considered for clinical use.

Disposition of cannabinoids in oral fluid after controlled around-the-clock oral THC administration

BACKGROUND

Oral fluid, a promising alternative matrix for drug monitoring in clinical and forensic investigations, offers noninvasive sample collection under direct observation. Cannabinoid distribution into oral fluid is complex and incompletely characterized due to the lack of controlled drug administration studies.

METHODS

To characterize cannabinoid disposition in oral fluid, we administered around-the-clock oral Delta(9)-tetrahydrocannabinol (THC) (Marinol) doses to 10 participants with current daily cannabis use. We obtained oral fluid samples (n=440) by use of Quantisal collection devices before, during, and after 37 20-mg THC doses over 9 days. Samples were extracted with multiple elution solvents from a single SPE column and analyzed by 2-dimensional GC-MS with electron-impact ionization for THC, 11-hydroxy-THC (11-OH-THC), cannabidiol, and cannabinol and negative chemical ionization for 11-nor-9-carboxy-THC (THCCOOH). Linear ranges were 0.5-50 microg/L, with the exception of cannabinol (1-50 microg/L) and THCCOOH (7.5-500 ng/L).

RESULTS

THCCOOH was the most prevalent analyte in 432 samples (98.2%), with concentrations up to 1117.9 ng/L. In contrast, 11-OH-THC was not identified in any sample; cannabidiol and cannabinol were quantified in 3 and 8 samples, respectively, with maximum concentrations of 2.1 and 13 microg/L. THC was present in only 20.7% of samples, with highest concentrations near admission (median 4.2 microg/L, range 0.6-481.9) from previously self-administered smoked cannabis.

CONCLUSIONS

Measurement of THCCOOH in OF not only identifies cannabis exposure, but also minimizes the possibility of passive inhalation. THCCOOH may be a better analyte for detection of cannabis use.

Cannabis and Amyotrophic Lateral Sclerosis: Hypothetical and Practical Applications, and a Call for Clinical Trials

Significant advances have increased our understanding of the molecular mechanisms of amyotrophic lateral sclerosis (ALS), yet this has not translated into any greatly effective therapies. It appears that a number of abnormal physiological processes occur simultaneously in this devastating disease. Ideally, a multidrug regimen, including glutamate antagonists, antioxidants, a centrally acting anti-inflammatory agent, microglial cell modulators (including tumor necrosis factor alpha [TNF-α] inhibitors), an antiapoptotic agent, 1 or more neurotrophic growth factors, and a mitochondrial function-enhancing agent would be required to comprehensively address the known pathophysiology of ALS. Remarkably, cannabis appears to have activity in all of those areas. Preclinical data indicate that cannabis has powerful antioxidative, anti-inflammatory, and neuroprotective effects. In the G93A-SOD1 ALS mouse, this has translated to prolonged neuronal cell survival, delayed onset, and slower progression of the disease. Cannabis also has properties applicable to symptom management of ALS, including analgesia, muscle relaxation, bronchodilation, saliva reduction, appetite stimulation, and sleep induction. With respect to the treatment of ALS, from both a disease modifying and symptom management viewpoint, clinical trials with cannabis are the next logical step. Based on the currently available scientific data, it is reasonable to think that cannabis might significantly slow the progression of ALS, potentially extending life expectancy and substantially reducing the overall burden of the disease.

Extended urinary Delta9-tetrahydrocannabinol excretion in chronic cannabis users precludes use as a biomarker of new drug exposure

BACKGROUND

Generally, urinary 11-nor-9-carboxy-Delta9-tetrahydrocannabinol (THCCOOH) after alkaline hydrolysis is monitored to detect cannabis exposure, although last use may have been weeks prior in chronic cannabis users. Delta9-Tetrahydrocannabinol (THC) and 11-hydroxy-THC (11-OH-THC) concentrations in urine following Escherichia coli beta-glucuronidase hydrolysis were proposed as biomarkers of recent (within 8h) cannabis use.

OBJECTIVE

To test the validity of THC and 11-OH-THC in urine as indicators of recent cannabis use.

METHODS

Monitor urinary cannabinoid excretion in 33 chronic cannabis smokers who resided on a secure research unit under 24h continuous medical surveillance. All urine specimens were collected individually ad libidum for up to 30 days, were hydrolyzed with a tandem E. coli beta-glucuronidase/base procedure, and analyzed for THC, 11-OH-THC and THCCOOH by one- and two-dimensional-cryotrap gas chromatography mass spectrometry (2D-GCMS) with limits of quantification of 2.5 ng/mL.

RESULTS

Extended excretion of THC and 11-OH-THC in chronic cannabis users' urine was observed during monitored abstinence; 14 of 33 participants had measurable THC in specimens collected at least 24h after abstinence initiation. Seven subjects had measurable THC in urine for 3, 3, 4, 7, 7, 12, and 24 days after cannabis cessation. 11-OH-THC and THCCOOH were detectable in urine specimens from one heavy, chronic cannabis user for at least 24 days.

CONCLUSION

For the first time, extended urinary excretion of THC and 11-OH-THC is documented for at least 24 days, negating their effectiveness as biomarkers of recent cannabis exposure, and substantiating long terminal elimination times for urinary cannabinoids following chronic cannabis smoking.

Pharmacokinetics of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (CTHC) after intravenous administration of CTHC in healthy human subjects

After cannabis consumption there is only limited knowledge about the pharmacokinetic (PK) and metabolic properties of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (CTHC), which is formed by oxidative breakdown from Delta(9)-tetrahydrocannabinol (THC). Despite widely-varying concentrations observed in smoking studies, attempts have been made to interpret consumption behavior with special regard to a cumulated or decreasing concentration of CTHC in serum. Ten healthy nonsmoking white male individuals received 5 mg CTHC intravenously over 10 min. Highest serum concentrations of CTHC were observed at the end of the infusion (336.8+/-61.7 microg/l) followed by a quick decline. CTHC concentration could be quantified up to 96 h after administration, with a terminal elimination half-life of 17.6+/-5.5 h. Total clearance was low (91.2+/-24.0 ml/min), with renal clearance having only a minor contribution (0.136+/-0.094 ml/min). This first metabolite-based kinetic approach will allow an advanced understanding of CTHC PKs data obtained in previous studies with THC.

Pharmacokinetics and metabolism of the plant cannabinoids, delta9-tetrahydrocannabinol, cannabidiol and cannabinol

Increasing interest in the biology, chemistry, pharmacology, and toxicology of cannabinoids and in the development of cannabinoid medications necessitates an understanding of cannabinoid pharmacokinetics and disposition into biological fluids and tissues. A drug's pharmacokinetics determines the onset, magnitude, and duration of its pharmacodynamic effects. This review of cannabinoid pharmacokinetics encompasses absorption following diverse routes of administration and from different drug formulations, distribution of analytes throughout the body, metabolism by different tissues and organs, elimination from the body in the feces, urine, sweat, oral fluid, and hair, and how these processes change over time. Cannabinoid pharmacokinetic research has been especially challenging due to low analyte concentrations, rapid and extensive metabolism, and physicochemical characteristics that hinder the separation of drugs of interest from biological matrices--and from each other--and lower drug recovery due to adsorption of compounds of interest to multiple surfaces. delta9-Tetrahydrocannabinol, the primary psychoactive component of Cannabis sativa, and its metabolites 11-hydroxy-delta9-tetrahydrocannabinol and 11-nor-9-carboxy-tetrahydrocannabinol are the focus of this chapter, although cannabidiol and cannabinol, two other cannabinoids with an interesting array of activities, will also be reviewed. Additional material will be presented on the interpretation of cannabinoid concentrations in human biological tissues and fluids following controlled drug administration.

Postmortem toxicology of drugs of abuse

Conducting toxicology on post-mortem specimens provides a number of very significant challenges to the scientist. The range of additional specimens include tissues such as decomposing blood and other tissues, hair, muscle, fat, lung, and even larvae feeding on the host require special techniques to isolate a foreign substance and allow detection without interference from the matrix. A number of drugs of abuse are unstable in the post-mortem environment that requires careful consideration when trying to interpret their significance. Heroin, morphine glucuronides, cocaine and the benzodiazepines are particularly prone to degradation. Moreover, redistributive process can significantly alter the concentration of drugs, particularly those with a higher tissue concentration than the surrounding blood. The designer amphetamines, methadone and other potent opioids will increase their concentration in blood post-mortem. These processes together with the development of tolerance means that no concentration of a drug of abuse can be interpreted in isolation without a thorough examination of the relevant circumstances and after the conduct of a post-mortem to eliminate or corroborate relevant factors that could impact on the drug concentration and the possible effect of a substance on the body. This article reviews particular toxicological issues associated with the more common drugs of abuse such as the amphetamines, cannabinoids, cocaine, opioids and the benzodiazepines.

Pharmacokinetics and pharmacodynamics of cannabinoids

Delta(9)-Tetrahydrocannabinol (THC) is the main source of the pharmacological effects caused by the consumption of cannabis, both the marijuana-like action and the medicinal benefits of the plant. However, its acid metabolite THC-COOH, the non-psychotropic cannabidiol (CBD), several cannabinoid analogues and newly discovered modulators of the endogenous cannabinoid system are also promising candidates for clinical research and therapeutic uses. Cannabinoids exert many effects through activation of G-protein-coupled cannabinoid receptors in the brain and peripheral tissues. Additionally, there is evidence for non-receptor-dependent mechanisms. Natural cannabis products and single cannabinoids are usually inhaled or taken orally; the rectal route, sublingual administration, transdermal delivery, eye drops and aerosols have only been used in a few studies and are of little relevance in practice today. The pharmacokinetics of THC vary as a function of its route of administration. Pulmonary assimilation of inhaled THC causes a maximum plasma concentration within minutes, psychotropic effects start within seconds to a few minutes, reach a maximum after 15-30 minutes, and taper off within 2-3 hours. Following oral ingestion, psychotropic effects set in with a delay of 30-90 minutes, reach their maximum after 2-3 hours and last for about 4-12 hours, depending on dose and specific effect. At doses exceeding the psychotropic threshold, ingestion of cannabis usually causes enhanced well-being and relaxation with an intensification of ordinary sensory experiences. The most important acute adverse effects caused by overdosing are anxiety and panic attacks, and with regard to somatic effects increased heart rate and changes in blood pressure. Regular use of cannabis may lead to dependency and to a mild withdrawal syndrome. The existence and the intensity of possible long-term adverse effects on psyche and cognition, immune system, fertility and pregnancy remain controversial. They are reported to be low in humans and do not preclude legitimate therapeutic use of cannabis-based drugs. Properties of cannabis that might be of therapeutic use include analgesia, muscle relaxation, immunosuppression, sedation, improvement of mood, stimulation of appetite, antiemesis, lowering of intraocular pressure, bronchodilation, neuroprotection and induction of apoptosis in cancer cells.

Marijuana in the management of amyotrophic lateral sclerosis

Marijuana has been proposed as treatment for a widening spectrum of medical conditions. Marijuana is a substance with many properties that may be applicable to the management of amyotrophic lateral sclerosis (ALS). These include analgesia, muscle relaxation, bronchodilation, saliva reduction, appetite stimulation, and sleep induction. In addition, marijuana has now been shown to have strong antioxidative and neuroprotective effects, which may prolong neuronal cell survival. In areas where it is legal to do so, marijuana should be considered in the pharmacological management of ALS. Further investigation into the usefulness of marijuana in this setting is warranted.