Review of the oral toxicity of cannabidiol (CBD)

Investigation of cannabidiol-induced cytotoxicity in human hepatic cells

Cannabidiol (CBD) is one of the primary cannabinoids present in extracts of the plant Cannabis sativa L. A CBD-based drug, Epidiolex, has been approved by the U.S. FDA for the treatment of seizures in childhood-onset epileptic disorders. Although CBD-associated liver toxicity has been reported in clinical studies, the underlying mechanisms remain unclear. In this study, we demonstrated that CBD causes cytotoxicity in primary human hepatocytes and hepatic HepG2 cells. A 24-h CBD treatment induced cell cycle disturbances, cellular apoptosis, and endoplasmic reticulum (ER) stress in HepG2 cells. A potent ER stress inhibitor, 4-phenylbutyrate, markedly attenuated CBD-induced apoptosis and cell death. Additionally, we investigated the role of cytochrome P450 (CYP)-mediated metabolism in CBD-induced cytotoxicity using HepG2 cell lines engineered to express 14 individual CYPs. We identified CYP2C9, 2C19, 2D6, 2C18, and 3A5 as participants in CBD metabolism. Notably, cells overexpressing CYP2C9, 2C19, and 2C18 produced 7-hydroxy-CBD, while cells overexpressing CYP2C9, 2C19, 2D6, and 2C18 generated 7-carboxy-CBD. Furthermore, CBD-induced cytotoxicity was significantly attenuated in the cells expressing CYP2D6. Taken together, these data suggest that cell cycle disturbances, apoptosis, and ER stress are associated with CBD-induced cytotoxicity, and CYP2D6-mediated metabolism plays a critical role in decreasing the cytotoxicity of CBD.

Examining the hepatotoxic potential of cannabidiol, cannabidiol-containing hemp extract, and cannabinol at consumer-relevant exposure concentrations in primary human hepatocytes

Hemp extracts and consumer products containing cannabidiol (CBD) and/or other phytocannabinoids derived from hemp have entered the marketplace in recent years. CBD is an approved drug in the United States for the treatment of certain seizure disorders. While effects of CBD in the liver have been well characterized, data on the effects of other cannabinoids and hemp extracts in the liver and methods for studying these effects in vitro are limited. This study examined the hepatotoxic potential of CBD, CBD concentration-matched hemp extract, and cannabinol (CBN), at consumer-relevant concentrations determined by in silico modeling, in vitro using primary human hepatocytes. Primary human hepatocytes exposed to between 10-nM and 25-μM CBD, CBN, or hemp extract for 24 and 48 h were evaluated by measuring lactate dehydrogenase release, apoptosis, albumin secretion, urea secretion, and mitochondrial membrane potential. Cell viability was not significantly affected by CBD, CBN, or the hemp extract at any of the concentrations tested. Exposure to hemp extract induced a modest but statistically significant decrease in albumin secretion, urea secretion, and mitochondrial membrane potential at the highest concentration tested whereas CBD only induced a modest but statistically significant decrease in albumin secretion compared with vehicle control. Although this study addresses data gaps in the understanding of cannabinoid hepatoxicity in vitro, additional studies will be needed to determine how these results correlate with relevant consumer exposure and the biological effects of cannabinoids in human liver.

Metabolism and liver toxicity of cannabidiol

Increasing public interest has resulted in the widespread use of non-pharmaceutical cannabidiol (CBD) products. The sales of CBD products continue to rise, accompanied by concerns regarding unsubstantiated benefits, lack of product quality control, and potential health risks. Both animal and human studies have revealed a spectrum of toxicological effects linked to the use of CBD. Adverse effects related to exposure of humans to CBD include changes in appetite, gastrointestinal discomfort, fatigue, and elevated liver aminotransferase enzymes. Animal studies reported changes in organ weight, reproduction, liver function, and the immune system. This review centers on human-derived data, including clinical studies and in vitro investigations. Animal studies are also included when human data is not available. The objective is to offer an overview of CBD-related hepatotoxicity, metabolism, and potential CBD-drug interactions, thereby providing insights into the current understanding of CBD's impact on human health. It's important to note that this review does not serve as a risk assessment but seeks to summarize available information to contribute to the broader understanding of potential toxicological effects of CBD on the liver.

Modulation of Oxidative Stress and Neuroinflammation by Cannabidiol (CBD): Promising Targets for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease and the most common form of dementia globally. Although the direct cause of AD remains under debate, neuroinflammation and oxidative stress are critical components in its pathogenesis and progression. As a result, compounds like cannabidiol (CBD) are being increasingly investigated for their ability to provide antioxidant and anti-inflammatory neuroprotection. CBD is the primary non-psychotropic phytocannabinoid derived from Cannabis sativa. It has been found to provide beneficial outcomes in a variety of medical conditions and is gaining increasing attention for its potential therapeutic application in AD. CBD is not psychoactive and its lipophilic nature allows its rapid distribution throughout the body, including across the blood-brain barrier (BBB). CBD also possesses anti-inflammatory, antioxidant, and neuroprotective properties, making it a viable candidate for AD treatment. This review outlines CBD's mechanism of action, the role of oxidative stress and neuroinflammation in AD, and the effectiveness and limitations of CBD in preclinical models of AD.

Decoding epilepsy treatment: A comparative evaluation contrasting cannabidiol pharmacokinetics in adult and paediatric populations

Epilepsy is a neurological disorder characterized by overstimulation of neurotransmitters and uncontrolled seizures. Current medications for epilepsy result in adverse effects or insufficient seizure control, highlighting the necessity to develop alternative therapies. Cannabidiol (CBD), derived from cannabis plants, has been popularly explored as an alternative. CBD is shown to have anti-convulsivatng and muscle-relaxing properties, which have been used in patients with epilepsy with promising results. Current research explores varying dosages in either adult or paediatric patients, with little or no comparison between the two populations. In this review, we aim at consolidating this data and comparing the effect and pharmacokinetic properties of CBD across these two patient populations. When comparing the absorption, there was insufficient data to show differences between paediatric and adult patients. Similarly, limited information was available in comparing the distribution of CBD, but a higher volume of distribution was found in the paediatric population. From the metabolism perspective, the paediatric population had a greater success rate when treated with the drug compared to the adult population. In the elimination, there were no clear distinctions in the clearance rate between the two populations. The drug's half-life was highly variable in both populations, with paediatrics having a lower range than adults. In summary, the paediatric population had a more significant reduction in the severity of seizures compared to the adult population upon CBD treatment. The complexity in which CBD operates highlights the need for further studies of the compound to further understand why differences occur between these two populations.

Pharmacovigilance of unlicensed cannabidiol in European countries

Cannabidiol (CBD) is a multitarget agent possessing anti-inflammatory and antioxidant properties. Unlicensed CBD gained public favor for the care of general health and well-being as well as to get comfort from inflammatory complaints, pain, anxiety, mood, and sleep disorders. Safety profile of unlicensed CBD has been not sufficiently described. For this reason, suspected adverse reactions (SARs) to CBD unlicensed products were analyzed. Serious SARs to unlicensed CBD products in EudraVigilance, a system purchased by the European Medicines Agency, were analyzed for age, sex of the patient, adverse reactions, indication for use, and concomitant drugs. Serious SARs were 18.9% of all adverse events to unlicensed CBD; they were more frequent in men and adult people and, to a less extent, in children (3-11 years). About sex, in EudraVigilance serious Individual Cases Safety Reports of SARs to CBD in men are in the largest number (58.8%) with respect to women. Unlicensed CBD was used in the 38.8% of cases for treatment of epilepsy; more frequent adverse effects were: mental disorders, hepatic disorders, and aggravation of pre-existing epilepsy. Drugs or substances more frequently associated with SARs were the antiepileptics clobazam and valproic acid, followed by cannabis. Results suggest that precautions and appropriate surveillance of adverse effects should be taken when unlicensed CBD is used.

Drug Interactions of Tetrahydrocannabinol and Cannabidiol in Cannabinoid Drugs

BACKGROUND

Cannabinoid drugs containing tetrahydrocannabinol (THC), or its structural analogues, as monotherapeutic agents or as extracts or botanical preparations with or without cannabidiol (CBD) are often prescribed to multimorbid patients who are taking multiple drugs. This raises the question of the risk of drug interactions.

METHODS

This review of the pharmacokinetics and pharmacodynamics of interactions with cannabinoid drugs and their potential effects is based on pertinent publications retrieved by a selective literature search.

RESULTS

As THC and CBD are largely metabolized in the liver, their bioavailability after oral or oral-mucosal administration is low (6-8% and 11-13%, respectively). The plasma concentrations of THC and its active metabolite 11-OH-THC can be increased by strong CYP3A4 inhibitors (verapamil, clarithromycin) and decreased by strong CYP3A4 inductors (rifampicin, carbamazepine). The clinical significance of these effects is unclear because of the variable plasma level and therapeutic spectrum of THC. The metabolism of CBD is less dependent on cytochrome P450 enzymes than that of THC. THC and CBD inhibit CYP2C and CYP3A4; the corresponding clinically relevant drug interactions probably are likely to arise only with THC doses above 30 mg/day and CBD doses above 300 mg/day.

CONCLUSION

Potential drug interactions with THC and CBD are probably of little importance at low or moderate doses. Strong CYP inhibitors or inductors can intensify or weaken their effect. Slowly ramping up the dose of oral cannabinoid drugs can lessen their pharmacodynamic interactions, which can generally be well controlled. Administration by inhalation can worsen the interactions.

Cannabidiol's impact on drug-metabolization

IMPORTANCE

Products containing cannabidiol(CBD) are easily accessible. CBD is reported to inhibit the drug-metabolizing proteins(DMP) Cytochrome P450(CYP)3A4/5, CYP2C9, CYP2B6, CYP2D6, CYP2E1, CYP1A2, CYP2C19, carboxylesterase 1(CES1), uridine 5'diphospho-glucoronosyltransferase(UGT)1A9, UGT2B7, P-glycoprotein(P-gp) and Breast Cancer Resistance Protein(BCRP). The relevance of CBD-drug interactions is largely unknown. Aim of the study was to identify drugs, potentially interacting with orally ingested CBD, to assess whether CBD-drug interactions have been reported, and if substrates of DMP are frequently prescribed drugs.

OBSERVATIONS

Identified were 403 drugs as substrates of DMP. CBD-drug interactions were reported for 53/403 substrates in humans (n = 25), in vivo (n = 13) or in vitro (n = 15). In 31/53 substrates, CBD induced an increase, in 1/53 a decrease, in 4/53 no change in the substrate level. For 5/53 substrates, the results were controversial, and in 12/53 no substrate levels were reported. Among the 30 most frequently prescribed drugs in Germany were 67% substrates of DMP and among the 50 most frequently prescribed drugs in the USA 68%.

RELEVANCE AND CONCLUSIONS

There is an urgent need for pharmacologic studies on CBD-drug interactions. Patients should be educated on the potential risk and awareness should be increased among physicians. Regulatory authorities should become aware of the problem and start an initiative on an international level to increase the safety of CBD.

Induction of apoptosis by cannabidiol and its main metabolites in human Leydig cells

Cannabidiol (CBD) is one of the most prevalent and abundant cannabinoids extracted from the plant Cannabis sativa. CBD has been reported to induce male reproductive toxicity in animal models. In this study, we examined the effects of CBD and its main metabolites, 7-carboxy-CBD and 7-hydroxy-CBD, on primary human Leydig cells, which play a crucial role in male reproductive health. Our results showed that CBD, at concentrations below the Bayesian benchmark dose (BMD)50, inhibited the growth of human Leydig cells by arresting the cell cycle at G1/S transition, disrupting cell cycle regulators, and decreasing DNA synthesis. Concentration-response transcriptomic profiling identified that apoptosis was one of the top biological processes significantly affected by treatment with CBD for 24 h. The occurrence of apoptosis was confirmed by increased activation of caspase-3/7 and an increased proportion of annexin V and propidium iodide (PI)-positive cells. Similar to CBD, both 7-carboxy-CBD and 7-hydroxy-CBD decreased cell viability and induced apoptosis after treatment for 24 h. 7-Hydroxy-CBD and 7-carboxy-CBD showed lower cytotoxicity than CBD, and 7-carboxy-CBD had the lowest cytotoxicity among the three compounds. Our findings revealed that CBD and its main metabolites can cause adverse effects on primary human Leydig cells.

Therapeutic considerations of bioactive compounds in Alzheimer's disease and Parkinson's disease: Dissecting the molecular pathways

Leading neurodegenerative diseases Alzheimer's disease (AD) and Parkinson's disease (PD) are characterized by the impairment of memory and motor functions, respectively. Despite several breakthroughs, there exists a lack of disease-modifying treatment strategies for these diseases, as the available drugs provide symptomatic relief and bring along side effects. Bioactive compounds are reported to bear neuroprotective properties with minimal toxicity, however, a detailed elucidation of their modes of neuroprotection is lacking. The review elucidates the neuroprotective mechanism(s) of some of the major phyto-compounds in pre-clinical and clinical studies of AD and PD to understand their potential in combating these diseases. Curcumin, eugenol, resveratrol, baicalein, sesamol and so on have proved efficient in countering the pathological hallmarks of AD and PD. Curcumin, resveratrol, caffeine and so on have reached the clinical phases of these diseases, while aromadendrin, delphinidin, cyanidin and xanthohumol are yet to be extensively explored in pre-clinical phases. The review highlights the need for extensive investigation of these compounds in the clinical stages of these diseases so as to utilize their disease-modifying abilities in the real field of treatment. Moreover, poor pharmacokinetic properties of natural compounds are constraints to their therapeutic yields and this review suggests a plausible contribution of nanotechnology in overcoming these limitations.

Are adverse effects of cannabidiol (CBD) products caused by tetrahydrocannabinol (THC) contamination?

Cannabidiol (CBD)-containing products are widely marketed as over the counter products, mostly as food supplements. Adverse effects reported in anecdotal consumer reports or during clinical studies were first assumed to be due to acid-catalysed cyclization of CBD to psychotropic Δ ⁹tetrahydrocannabinol (Δ ⁹-THC) in the stomach after oral consumption. However, research of pure CBD solutions stored in simulated gastric juice or subjected to various storage conditions such as heat and light with specific liquid chromatographic/tandem mass spectrometric (LC/MS/MS) and ultra-high pressure liquid chromatographic/quadrupole time-of-flight mass spectrometric (UPLC-QTOF) analyses was unable to confirm THC formation. Another hypothesis for the adverse effects of CBD products may be residual Δ ⁹-THC concentrations in the products as contamination, because most of them are based on hemp extracts containing the full spectrum of cannabinoids besides CBD. Analyses of 362 hemp-based products of the German market (mostly CBD oils) confirmed this hypothesis: 39 products (11%) contained Δ ⁹-THC above the lowest observed adverse effect level (2.5 mg/day). Hence, it may be assumed that the adverse effects of some commercial CBD products are based on a low-dose effect of Δ ⁹-THC, with the safety of CBD itself currently being unclear with significant uncertainties regarding possible liver and reproductive toxicity. The safety, efficacy and purity of commercial CBD products is highly questionable, and all of the products in our sample collection showed various non-conformities to European food law such as unsafe Δ ⁹-THC levels, hemp extracts or CBD isolates as non-approved novel food ingredients, non-approved health claims, and deficits in mandatory food labelling requirements. In view of the growing market for such lifestyle products, the effectiveness of the instrument of food business operators' own responsibility for product safety and regulatory compliance must obviously be challenged, and a strong regulatory framework for hemp products needs to be devised.