Pharmacokinetics of Oral Minor Cannabinoids in Blood and Brain

Introduction: Minor cannabinoids are increasingly being consumed in oral formulations (i.e., edibles, tinctures) for medical and nonmedical purposes. This study examined the pharmacokinetics (PKs) of cannabinoids tetrahydrocannabivarin (THCV), cannabichromene (CBC), cannabinol (CBN), and delta-8-tetrahydrocannabinol (D8-THC) after the first and last oral dose during a 14-day administration period. Materials and Methods: Sprague-Dawley rats (N=6 animals/dose, 50% female) were given an assigned dose of one of four cannabinoids (THCV=3.2-100 mg/kg, CBC=3.2-100 mg/kg, CBN=1-100 mg/kg, or D8-THC=0.32-10 mg/kg) or vehicle (medium-chain triglyceride oil) through oral gavage once daily for 14 days. Blood was collected 45 min and 1.5, 3, and 24 h following the first dose (day 1) and the last dose (day 14) of repeated oral cannabinoid treatment for PK analysis. Outcomes of interest included time to maximum concentration (Tmax), maximum concentration (Cmax), and area under the concentration versus time curve (AUClast). Dose-normalized (DN) Cmax and DN AUClast were also calculated. Brain tissue was collected 24 h post-administration of the first (day 1) and the last (day 14) dose of each cannabinoid to determine concentrations in brain. Results: All cannabinoids tested were detectable in plasma after single and 14-day repeated dosing. DN Cmax and DN AUClast were highest for D8-THC, followed by CBC, CBN, and THCV. There was no sex difference observed in cannabinoid kinetics. Accumulation of D8-THC in plasma was observed after 14 days of administration. THCV levels in plasma were lower on day 14 compared to day 1, indicating potential adaptation of metabolic pathways and increased drug elimination. Cannabinoids were detected in brain tissue 24 h post-administration of the first and the last dose of 17-100 mg/kg THCV, 3.2-100 mg/kg CBC, 10-100 mg/kg CBN, and 10 mg/kg D8-THC. Conclusions: THCV, CBC, CBN, and D8-THC produced detectable levels in plasma and translocated to brain tissue after the first dose (day 1) and the last dose (day 14) of repeated oral dosing. Examination of PKs of these minor cannabinoids in blood and brain provides a critical step for informing target dose ranges and dosing schedules in future studies that evaluate the potential effects of these compounds.

Toxicological Evaluation and Pain Assessment of Four Minor Cannabinoids Following 14-Day Oral Administration in Rats

Introduction: Despite growing consumer interest and market availability, the safety of minor cannabinoids, generally present in low concentrations in Cannabis sativa L., is not well understood. Materials and Methods: Cannabichromene (CBC; 3.2, 10, 17, 22, 32, or 100 mg/kg-bw/day), cannabinol (CBN; 1, 3.2, 10, 17, 32, or 100 mg/kg-bw/day), delta-8-tetrahydrocannabinol (D8-THC; 0.32, 1, 3.2, or 10 mg/kg-bw/day), tetrahydrocannabivarin (THCV; 3.2, 10, 17, 22, 32, or 100 mg/kg-bw/day), and vehicle (medium-chain triglyceride oil) preparations were administered via oral gavage once daily for 14 days to Sprague Dawley rats. Changes in behavior, body weight, food consumption, clinical pathology, organ weights, body temperature, and thermal pain sensitivity (tail flick assay) were assessed. Select organ tissues were collected at terminal necropsy and fixed for histopathological examination. Results: No treatment-related deaths were observed throughout the study, and cannabinoids were generally well tolerated. While some significant trends in body weight differences from controls (increases and decreases) were observed, these occurred independently of food consumption. Overall, differences in serum chemistry and hematology parameters between cannabinoid groups and their respective control groups were considered to occur due to biological variation among rats. No treatment-related gross abnormalities were observed in examined organs. Significant changes in absolute and relative organ weights occurred primarily in males and were generally of negligible magnitude. There were no biologically significant histopathological observations. While pain tolerance was significantly improved in animals treated with D8-THC (3.2 and 10 mg/kg-bw/day, day 14), results across minor cannabinoids were inconsistent and warrant further study. Conclusion: Minor cannabinoids were well tolerated across 14 days of daily oral administration at the doses assessed. Modest, dose-dependent trends in relative organ weights and serum chemistry parameters warrant exploration at higher oral doses. These data will assist in dose selection for future studies investigating the long-term safety and effects of CBC, CBN, D8-THC, and THCV.

Pharmacokinetics of Cannabidiol in Sprague-Dawley Rats After Oral and Pulmonary Administration

Introduction: Cannabidiol (CBD) is primarily consumed through ingestion and inhalation. Little is known about how CBD pharmacokinetics differ between routes of administration, and duration of pulmonary exposure. Methods: Pharmacokinetics, brain distribution, and urinary elimination of CBD and its major metabolites (6-hydroxy-cannabidiol [6-OH-CBD], 7-hydroxy-cannabidiol [7-OH-CBD], 7-carboxy-cannabidiol [7-COOH-CBD], and CBD-glucuronide) were evaluated in adult Sprague-Dawley rats following a single oral CBD ingestion (10 mg/kg in medium chain triglyceride oil; 24 male animals), and 1 or 14 days of repeated inhalation (0.9-13.9 mg/kg in propylene glycol [41%/59% by weight]; 5 male and 5 female animals per dose). Blood and brain tissue were collected at a single time point from each animal. Collection times were staggered from 5 min to 24 h postoral gavage or first (blood only) and final inhalation. Urine was collected 24 h postoral gavage or final inhalation. Samples were analyzed through liquid chromatography-mass spectrometry (LC-MS/MS). Results: CBD was more rapidly absorbed following inhalation than ingestion (T_max=5 min and 2 h, respectively). Inhalation resulted in a dose-responsive increase in CBD C_max and AUC_last. CBD C_max was 24-fold higher following the highest pulmonary dose (13.9 mg/kg) versus an oral dose of comparable concentration (10 mg/kg). C_max and AUC_last (0-16 h) trended higher following repeated exposure. Elimination was notably faster with repeated CBD inhalation (t_1/2=5.3 and 2.4 h on days 1 and 14, respectively). While metabolites were detectable in plasma, AUC_last (0-2 h) was at least 10- (7-OH-CBD, 7-COOH-CBD) to 100- (6-OH-CBD) fold lower than the parent compound. Metabolite concentration trended higher following repeated inhalation (6.7 mg/kg CBD); AUC_last (0-16 h) was ∼1.8-, ∼1.4-, and ∼2.4-fold higher following 14 days of exposure for 6-OH-CBD, 7-OH-CBD, and 7-COOH-CBD, respectively. CBD was detectable in brain homogenate tissue 24-h after 14-day inhalation (>3.5 mg/kg deposited dose) or a single oral administration. CBD metabolites were only measurable in brain tissue following the highest inhaled dose (13.9 mg/kg CBD). CBD, but not metabolites, was detectable in urine for all dose groups following 2 weeks of CBD inhalation. Neither CBD nor metabolites were present in urine after oral administration. Conclusion: CBD pharmacokinetics differ across oral and pulmonary routes of administration and acute or repeated dosing.

Use of Medical Cannabis to Treat Traumatic Brain Injury

There is not a single pharmacological agent with demonstrated therapeutic efficacy for traumatic brain injury (TBI). With recent legalization efforts and the growing popularity of medical cannabis, patients with TBI will inevitably consider medical cannabis as a treatment option. Pre-clinical TBI research suggests that cannabinoids have neuroprotective and psychotherapeutic properties. In contrast, recreational cannabis use has consistently shown to have detrimental effects. Our review identified a paucity of high-quality studies examining the beneficial and adverse effects of medical cannabis on TBI, with only a single phase III randomized control trial. However, observational studies demonstrate that TBI patients are using medical and recreational cannabis to treat their symptoms, highlighting inconsistencies between public policy, perception of potential efficacy, and the dearth of empirical evidence. We conclude that randomized controlled trials and prospective studies with appropriate control groups are necessary to fully understand the efficacy and potential adverse effects of medical cannabis for TBI.

Phytol, not propylene glycol, causes severe pulmonary injury after inhalation dosing in Sprague-Dawley rats

Introduction: The use of vaping pens for inhalation of cannabinoid derived products is rising and has become a popular alternative to smoking combustible products. For efficient product delivery, additives are sometimes added and vaping pens often may include compounds like Phytol or Propylene Glycol as thinning agents. This study aimed at comparing Phytol and Propylene Glycol with respect to potential toxicity and safe use in vaping products.Methods: Male and female Sprague Dawley rats were exposed to 5 mg/L of Phytol or Propylene Glycol for up to 6 hours over up to 14 days and monitored for clinical signs and changes in body weight. Gross necropsy and histopathology of respiratory tissue was performed to assess potential adverse effects.Results: Phytol exposed animals expressed severe clinical signs, body weight loss and mortality after one or two exposure days, leading to termination of all dose groups for this compound. Lung weights were increased and respiratory tissue was severely affected, demonstrating dose-responsive tissue degeneration, necrosis, edema, hemorrhage and inflammation. Propylene Glycol exposed animals did not show any adverse reactions after 14 days of high dose exposure.Conclusions: For Phytol, a low observed adverse effect level (LOAEL) was determined at ≤109.0/10.9 mg/kg/day presented/deposited dose and therefore its use as excipient in vaping product is not recommend; a safe exposure range was not established for Phytol. Propylene Glycol, in contrast, is considered safe with a no observed adverse effect level (NOAEL) at 1151.7/115.2 mg/kg/day presented/deposited dose in rats.

Cerium oxide and barium sulfate nanoparticle inhalation affects gene expression in alveolar epithelial cells type II

BACKGROUND

Understanding the molecular mechanisms of nanomaterial interacting with cellular systems is important for appropriate risk assessment. The identification of early biomarkers for potential (sub-)chronic effects of nanoparticles provides a promising approach towards cost-intensive and animal consuming long-term studies. As part of a 90-day inhalation toxicity study with CeO₂ NM-212 and BaSO₄ NM-220 the present investigations on gene expression and immunohistochemistry should reveal details on underlying mechanisms of pulmonary effects. The role of alveolar epithelial cells type II (AEII cells) is focused since its contribution to defense against inhaled particles and potentially resulting adverse effects is assumed. Low dose levels should help to specify particle-related events, including inflammation and oxidative stress.

RESULTS

Rats were exposed to clean air, 0.1, 0.3, 1.0, and 3.0 mg/m³ CeO₂ NM-212 or 50.0 mg/m³ BaSO₄ NM-220 and the expression of 391 genes was analyzed in AEII cells after one, 28 and 90 days exposure. A total number of 34 genes was regulated, most of them related to inflammatory mediators. Marked changes in gene expression were measured for Ccl2, Ccl7, Ccl17, Ccl22, Ccl3, Ccl4, Il-1α, Il-1ß, and Il-1rn (inflammation), Lpo and Noxo1 (oxidative stress), and Mmp12 (inflammation/lung cancer). Genes related to genotoxicity and apoptosis did not display marked regulation. Although gene expression was less affected by BaSO₄ compared to CeO₂ the gene pattern showed great overlap. Gene expression was further analyzed in liver and kidney tissue showing inflammatory responses in both organs and marked downregulation of oxidative stress related genes in the kidney. Increases in the amount of Ce were measured in liver but not in kidney tissue. Investigation of selected genes on protein level revealed increased Ccl2 in bronchoalveolar lavage of exposed animals and increased Lpo and Mmp12 in the alveolar epithelia.

CONCLUSION

AEII cells contribute to CeO₂ nanoparticle caused inflammatory and oxidative stress reactions in the respiratory tract by the release of related mediators. Effects of BaSO₄ exposure are low. However, overlap between both substances were detected and support identification of potential early biomarkers for nanoparticle effects on the respiratory system. Signs for long-term effects need to be further evaluated by comparison to a respective exposure setting.

Effects from a 90-day inhalation toxicity study with cerium oxide and barium sulfate nanoparticles in rats

Background

Nanomaterials like cerium oxide and barium sulfate are frequently processed in industrial and consumer products and exposure of humans and other organisms is likely. Generally less information is given on health effects and toxicity, especially regarding long-term exposure to low nanoparticle doses. Since inhalation is still the major route of uptake the present study focused on pulmonary effects of CeO₂NM-212 (0.1, 0.3, 1.0, 3.0 mg/m³) and BaSO₄NM-220 nanoparticles (50.0 mg/m³) in a 90-day exposure setup. To define particle-related effects and potential mechanisms of action, observations in histopathology, bronchoalveolar lavage and immunohistochemistry were linked to pulmonary deposition and clearance rates. This further allows evaluation of potential overload related effects.

Results

Lung burden values increased with increasing nanoparticle dose levels and ongoing exposure. At higher doses, cerium clearance was impaired, suggesting lung overload. Barium elimination was extremely rapid and without any signs of overload. Bronchoalveolar lavage fluid analysis and histopathology revealed lung tissue inflammation with increasing severity and post-exposure persistency for CeO₂. Also, marker levels for genotoxicity and cell proliferation were significantly increased. BaSO₄ showed less inflammation or persistency of effects and particularly affected the nasal cavity.

Conclusion

CeO₂ nanoparticles penetrate the alveolar space and affect the respiratory tract after inhalation mainly in terms of inflammation. Effects at low dose levels and post-exposure persistency suggest potential long-term effects and a notable relevance for human health. The generated data might be useful to improve nanoparticle risk assessment and threshold value generation. Mechanistic investigations at conditions of non-overload and absent inflammation should be further investigated in future studies.

The validation of a 15 STR multiplex PCR for Cannabis species

Trade and acquisition of Cannabis drugs are illegal in many countries worldwide; nevertheless, crimes related with these drugs are a major problem for the investigative authorities. With this manuscript, we want to introduce a 15 short tandem repeat (STR) Cannabis marker set that can be amplified in one PCR reaction. This multiplex PCR is specific to Cannabis species and combines highly informative STR markers. The 15 STR multiplex is easy to use and was validated according to common laboratory quality standards. Due to the fact that a lot of Cannabis plants are cultivated by clonal propagation and may show aneuploidy, polyploidy or multiple gene loci, it is not possible to apply biostatistics that follow the Hardy-Weinberg law. However, this multiplex will help the police to trace back trade routes of drug syndicates or dealers and it can help to link Cannabis plants to a crime scene.