Cannabinoid therapy in epilepsy

Integrating endocannabinoid signaling, CCK interneurons, and hippocampal circuit dynamics in behaving animals

The brain's endocannabinoid signaling system modulates a diverse range of physiological phenomena and is also involved in various psychiatric and neurological disorders. The basic components of the molecular machinery underlying endocannabinoid-mediated synaptic signaling have been known for decades. However, limitations associated with the short-lived nature of endocannabinoid lipid signals had made it challenging to determine the spatiotemporal specificity and dynamics of endocannabinoid signaling in vivo. Here, we discuss how novel technologies have recently enabled unprecedented insights into endocannabinoid signaling taking place at specific synapses in behaving animals. In this review, we primarily focus on cannabinoid-sensitive inhibition in the hippocampus in relation to place cell properties to illustrate the potential of these novel methodologies. In addition, we highlight implications of these approaches and insights for the unraveling of cannabinoid regulation of synapses in vivo in other brain circuits in both health and disease.

Chromosome-level Haploid Assembly of Cannabis sativa L. cv. Pink Pepper

As molecular research on hemp (Cannabis sativa L.) continues to advance, there is a growing need for the accumulation of more diverse genome data and more accurate genome assemblies. In this study, we report the three-way assembly data of a cannabidiol (CBD)-rich cannabis variety, 'Pink Pepper' cultivar using sequencing technology: PacBio Single Molecule Real-Time (SMRT) technology, Illumina sequencing technology, and Oxford Nanopore Technology (ONT). This assembly anchors scaffolds to the ten chromosomes of hemp, and to avoid confusion with previous cannabis genetic research, the chromosomes have been labeled based on an earlier reference genome. The total assembled genome length is 770 Gbp, with a GC content of 34.09% and a repeat region accounting for 77.13% of the genome. This assembly, which incorporates the unique strengths of the three sequencing technologies, demonstrated the highest complete BUSCO scores (97.8%-99.6%) among the reported cannabis genomes, as evaluated using three different BUSCO databases. With annotations for 30,459 protein-coding genes, this dataset can serve as a valuable resource for advancing genetic research on hemp.

Phytochemistry and pharmacological activities of Cannabis sativa fruit (Cannabis Fructus)

Cannabis sativa fruit (Cannabis Fructus) refers to the dried and ripe fruit of Cannabis sativa L. It is widely distributed in the northeast, North, and South China. It has medicinal, ecological, and economic values. This study aimed to review the chemical constituents and pharmacological activities of Cannabis Fructus, providing a reference for further exploration of Cannabis Fructus. Comprehensive information on Cannabis Fructus was collected via electronic searches (e.g., Google Scholar, PubMed, Sci Finder, and Web of Science) and from books on phytochemistry. Cannabis Fructus contains various compounds such as phenylpropanoids, flavonoids, steroids and terpenoids, cannabinoids, fatty acids, alkaloids, phenanthrenes, proteins, and polysaccharides. Its active ingredients exhibit anti-inflammatory, anti-oxidant, anti-bacterial, anti-aging, anti-fatigue, anti-tumor, anti-constipation, neuroprotective, lipoid-regulating, hepatoprotective, and immunomodulatory properties.

Physiological profiling of cannabidiol reveals profound inhibition of sensory neurons

ABSTRACT

Cannabidiol (CBD), the main nonpsychoactive cannabinoid of cannabis, holds promise for nonaddictive treatment of pain. Although preclinical studies have been encouraging, well-controlled human trials have been largely unsuccessful. To investigate this dichotomy and better understand the actions of CBD, we used high-content calcium imaging with automated liquid handling and observed broad inhibition of neuronal activation by a host of ionotropic and metabotropic receptors, including transient receptor potential (Trp) and purinergic receptors, as well as mediators of intracellular calcium cycling. To assess the effect of CBD on overall nociceptor electrical activity, we combined the light-activated ion channel channelrhodposin in TRPV1-positive nociceptors and a red-shifted calcium indicator and found that 1 µM CBD profoundly increased the optical threshold for calcium flux activation. Experiments using traditional whole-cell patch-clamp showed increase of nociceptor activation threshold at submicromolar concentrations, but with unusually slow kinetics, as well as block of voltage-activated currents. To address a more integrated capacity of CBD to influence nociceptor sensitization, a process implicated in multiple pain states, we found that submicromolar concentrations of CBD inhibited sensitization by the chemotherapeutic drug vincristine. Taken together, these results demonstrate that CBD can reduce neuronal activity evoked by a strikingly wide range of stimuli implicated in pain signaling. The extensive effects underscore the need for further studies at substantially lower drug concentrations, which are more likely to reflect physiologically relevant mechanisms. The slow kinetics and block raise biophysical questions regarding the lipophilic properties of CBD and its action on channels and receptors within membranes.

A randomized, double-blind, placebo-controlled, dose-escalating phase IIa trial to evaluate the safety, tolerability, efficacy, and pharmacokinetics of multiple oral doses of Pynegabine tablets as add-on therapy in patients with focal epilepsy

AIMS

This study aims to investigate the safety, tolerability, efficacy, and pharmacokinetics of Pynegabine as an add-on therapy in the treatment of focal epilepsy.

METHODOLOGY

This is a protocol phase-IIa, randomized, double-blinded, placebo-controlled, multicenter study in patients with focal epilepsy from multiple centers in China who have been treated with at least 2 ASMs without effective control. The study involves an 8-week run-in period with stable use of previous medications. Patients are then randomized to receive either Pynegabine or a placebo. Sentinel administration is performed initially, and subsequent patients are randomized based on safety assessments. Three dose cohorts (15, 20, and 25 mg/d) are established. Efficacy is assessed through various measures, including seizure frequency, CGI score, PGI score, HAMA score, HAMD score, MoCA scale score, QOLIE-31 scale score, and 12 h-EEG score. Safety evaluations, PK blood samples, concomitant medications, and adverse events are also recorded.

CONCLUSION

Data from the study will be used to evaluate the safety, tolerability, efficacy, and pharmacokinetics of Pynegabine tablets as add-on therapy for focal epilepsy.

Effectiveness of cannabidiol (CBD) on histopathological changes and gene expression in hepatocellular carcinoma (HCC) model in male rats: the role of Hedgehog (Hh) signaling pathway

The third most prevalent malignancy to cause mortality is hepatocellular carcinoma (HCC). The Hedgehog (Hh) signaling pathway is activated by binding to the transmembrane receptor Patched-1 (PTCH-1), which depresses the transmembrane G protein-coupled receptor Smoothened (SMO). This study was performed to examine the preventative and therapeutic effects of cannabidiol in adult rats exposed to diethyl nitrosamine (DENA)-induced HCC.A total of 50 male rats were divided into five groups of 10 rats each. Group I was the control group. Group II received intraperitoneal (IP) injections of DENA for 14 weeks. Group III included rats that received cannabidiol (CBD) orally (3-30 mg/kg) for 2 weeks and DENA injections for 14 weeks. Group IV rats received oral CBD for 2 weeks before 14 weeks of DENA injections. Group V included rats that received CBD orally for 2 weeks after their last injection of DENA. Measurements were made for alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glutamyl transferase (GGT), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and alpha fetoprotein (AFP). Following total RNA extraction, Smo, Hhip, Ptch-1, and Gli-1 expressions were measured using quantitative real-time polymerase chain reaction (qRT-PCR). A histopathological analysis of liver tissues was performed.The liver enzymes, oxidant-antioxidant state, morphological, and molecular parameters of the adult male rat model of DENA-induced HCC showed a beneficial improvement after CBD administration. In conclusion, by focusing on the Hh signaling system, administration of CBD showed a beneficial improvement in the liver enzymes, oxidant-antioxidant status, morphological, and molecular parameters in the DENA-induced HCC in adult male rats.

Functionally-selective inhibition of threshold sodium currents and excitability in dorsal root ganglion neurons by cannabinol

Cannabinol (CBN), an incompletely understood metabolite for ∆9-tetrahydrocannabinol, has been suggested as an analgesic. CBN interacts with endocannabinoid (CB) receptors, but is also reported to interact with non-CB targets, including various ion channels. We assessed CBN effects on voltage-dependent sodium (Nav) channels expressed heterologously and in native dorsal root ganglion (DRG) neurons. Our results indicate that CBN is a functionally-selective, but structurally-non-selective Nav current inhibitor. CBN's main effect is on slow inactivation. CBN slows recovery from slow-inactivated states, and hyperpolarizes steady-state inactivation, as channels enter deeper and slower inactivated states. Multielectrode array recordings indicate that CBN attenuates DRG neuron excitability. Voltage- and current-clamp analysis of freshly isolated DRG neurons via our automated patch-clamp platform confirmed these findings. The inhibitory effects of CBN on Nav currents and on DRG neuron excitability add a new dimension to its actions and suggest that this cannabinoid may be useful for neuropathic pain.

Long-term efficacy and adverse effects of cannabidiol in adjuvant treatment of drug-resistant epilepsy: a systematic review and meta-analysis

Background

Epilepsy is one of the most common chronic brain diseases. Almost one-third of patients have drug-resistant epilepsy (DRE). Cannabidiol is being considered as a potential novel drug for treating DRE.

Objectives

To investigate long-term efficacy and safety of cannabidiol in treatment of DRE and the differences in cannabidiol treatment among patients with different characteristics.

Design

Systematic review and meta-analysis.

Data sources and methods

Medline, Embase, and CENTRAL were searched for literature. RevMan5.4 was used for meta-analysis. The Intention-to-treat set and the random effect were used as the main analysis. Subgroup analyses were performed according to age, dose, concomitant antiseizure medications (ASMs), epilepsy syndromes, and study designs.

Results

Fifty studies were included in this systematic review. A total of 4791 participants were collected. The responder rates (seizure frequency reduced at least 50%) at 12-, 24-, 48-, 72-, 96-, and 144-week were 0.40 [0.36, 0.45], 0.39 [0.34, 0.44], 0.37 [0.30, 0.44], 0.27 [0.17, 0.37], 0.22 [0.14, 0.30], and 0.38 [0.23, 0.53]. Seizure-free rates were 0.04 [0.03, 0.06], 0.04 [0.03, 0.05], 0.03 [0.02, 0.05], 0.03 [0.02, 0.03], 0.02 [0.01, 0.03], and 0.04 [0.01, 0.06]. Proportion of adverse events were 0.72 [0.61, 0.83], 0.62 [0.42, 0.81], 0.60 [0.41, 0.79], 0.35 [0.14, 0.56], 0.83 [0.75, 0.90], and 0.96 [0.94, 0.99]. The pooled 12-, 24-, 48-, 96-, and 144-week proportion of serious adverse events were 0.15 [0.09, 0.21], 0.23 [0.14, 0.31], 0.10 [0.06, 0.15], 0.31 [0.24, 0.38], and 0.40 [0.35, 0.45]. Subgroup analyses showed that there was no significant difference on efficacy and safety among age subgroups and epilepsy syndromes subgroups. For most periods, there were no significant difference on efficacy among subgroups of dose and concomitant ASMs. However, higher doses and more concomitant ASMs were associated with higher proportion of adverse events.

Conclusion

Cannabidiol treatment of DRE has stable efficacy and fewer adverse events in early period. Long-term use may have decreased efficacy and increased adverse events. Dose escalation may not increase efficacy, but may increase adverse events. Furthermore, cannabidiol use may reduce dosage of other ASMs without reducing efficacy, thereby reducing adverse effects. Cannabidiol may have similar effects in various epilepsy syndromes.

Trial registration

PROSPERO (CRD42022351250).

Genotoxicity evaluation of cannabidiol

Consumer use of cannabidiol (CBD) for personal wellness purposes has garnered much public interest. However, safety-related data on CBD in the public domain are limited, including a lack of quality studies evaluating its genotoxic potential. The quality of available studies is limited due to the test material used (e.g., low CBD purity) and/or study design, leading some global regulatory agencies to highlight genotoxicity as an important data gap for CBD. To address this gap, the genotoxic potential of a pure CBD isolate was investigated in a battery of three genotoxicity assays conducted according to OECD testing guidelines. In an in vitro microbial reverse mutation assay, CBD up to 5000 μg/plate was negative in Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537, and Escherichia coli strain WP2 uvrA, with and without metabolic activation. Testing in an in vitro micronucleus assay was negative in human TK6 cells up to 10-11 μg/mL, with and without metabolic activation. Finally, an in vivo micronucleus assay conducted in male and female rats was negative for genotoxicity up to 1000 mg/kg-bw/d. Bioanalysis of CBD and its primary metabolite, 7-carboxy CBD, confirmed a dose-related increase in plasma exposure. Together, these assays indicate that CBD is unlikely to pose a genotoxic hazard.

Cannabidiol as an adjuvant treatment in adults with drug-resistant focal epilepsy

Cannabidiol oil (CBD) has been approved as an anti-seizure medication for the treatment of uncommon types of epilepsy, occurring in children: Dravet syndrome, Lennox-Gastaut syndrome, and Tuberous Sclerosis Complex. There are few publications in relation to use the CBD in adult patients with focal drug-resistant epilepsy. The objective of this study was to evaluate the efficacy, tolerability, safety, and quality of life, of adjuvant treatment with CBD, in adult patients with drug-resistant focal epilepsy for at least 6 months. An open, observational, prospective cohort study was conducted using a before-after design (time series) in adult patients undergoing outpatient follow-up in a public hospital in Buenos Aires, Argentina. From a total of 44 patients, 5% of patients were seizure-free, 32% of patients reduced more than 80% of their seizures and 87% of patients reduced 50% of their monthly seizures. Eleven percent presented a decrease of less than 50% in seizure frequency. The average final dose was 335 mg/d orally administered. Thirty-four percent of patients reported mild adverse events and no patient reported severe adverse effects. At the end of the study, we found in most patients a significant improvement in the quality of life, in all the items evaluated. Adjuvant treatment with CBD in adult patients with drug-resistant focal epilepsy was effective, safe, well tolerated, and associated with a significant improvement in their quality of life.

The Role of Cannabinoids in CNS Development: Focus on Proliferation and Cell Death

The active principles of Cannabis sativa are potential treatments for several diseases, such as pain, seizures and anorexia. With the increase in the use of cannabis for medicinal purposes, a more careful assessment of the possible impacts on embryonic development becomes necessary. Surveys indicate that approximately 3.9% of pregnant women use cannabis in a recreational and/or medicinal manner. However, although the literature has already described the presence of endocannabinoid system components since the early stages of CNS development, many of their physiological effects during this stage have not yet been established. Moreover, it is still uncertain how the endocannabinoid system can be altered in terms of cell proliferation and cell fate, neural migration, neural differentiation, synaptogenesis and particularly cell death. In relation to cell death in the CNS, knowledge about the effects of cannabinoids is scarce. Thus, the present work aims to review the role of the endocannabinoid system in different aspects of CNS development and discuss possible side effects or even opportunities for treating some conditions in the development of this tissue.

The electrophysiological and behavioral evaluation of the peptide hemopressin and cannabinoid CB1 receptor agonist and antagonist in pentylenetetrazol model of epilepsy in rats

This study endeavoured to assess the effect of hemopressin (Hp), a nano peptide obtained from the alpha chain of hemoglobin, on chronic epileptic activity and its potential correlation with cannabinoid receptor type 1 (CB1). Male Wistar albino rats (230-260 g) were used. The kindling process was conducted by administering a sub-convulsant dose of pentylenetetrazol (PTZ) (35 mg/kg, i.p) three times a week for a maximum of 10 weeks. Tripolar electrodes and external cannula guides for intracerebroventricular (i.c.v) injections were surgically implanted in the skulls of kindled rats. On the day of the experiment, doses of Hp, AM-251, and ACEA were administered prior to the PTZ injections. Electroencephalography recordings and behavioural observations were conducted simultaneously for 30 min after the PTZ injection. The administration of Hp (0.6 μg, i.c.v) resulted in a decrease in epileptic activity. The CB1 receptor agonist ACEA (7.5 μg, i.c.v) showed an anticonvulsant effect, but the CB1 receptor antagonist AM-251 (0.5 μg, i.c.v) displayed a proconvulsant effect. The co-administration of Hp (0.6 μg, i.c.v) and ACEA (7.5 μg, i.c.v) and of Hp (0.6 μg, i.c.v) and AM-251 (0.5 μg, i.c.v) produced an anticonvulsant effect. However, when AM-251 was administered prior to Hp, it produced a proconvulsant impact that overrode Hp's intended anticonvulsant effect. Interestingly, the co-administration of Hp (0.03 μg) + AM-251 (0.125 μg) unexpectedly exhibited an anticonvulsant effect. Electrophysiological and behavioural evaluations demonstrated the anticonvulsant effect of Hp in the present model, highlighting the possibility that Hp may act as an agonist for the CB1 receptor.

Reproductive and developmental toxicity evaluation of cannabidiol

An important data gap in determining a safe level of cannabidiol (CBD) intake for consumer use is determination of CBD's potential to cause reproductive or developmental toxicity. We conducted an OECD Test Guideline 421 GLP-compliant study in rats, with extended postnatal dosing and hormone analysis, where hemp-derived CBD isolate (0, 30, 100, or 300 mg/kg-bw/d) was administered orally. Treatment-related mortality, moribundity, and decreased body weight and food consumption were observed in high-dose F₀ adult animals, consistent with severe maternal toxicity. No effects were observed on testosterone concentrations, F₀ reproductive performance, or reproductive organs. Hepatocellular hypertrophy in the 100- and 300 mg/kg-bw/day groups correlated with hypertrophy/hyperplasia in the thyroid gland and changes in mean thyroid hormone concentrations in F₀ animals. Mean gestation length was unaffected; however, total litter loss for two females and dystocia for two additional females in the high-dose group occurred. Other developmental effects were limited to lower mean pup weights in the 300 mg/kg-bw/d group than those of controls. The following NOAELs were identified for CBD isolate based on this study: 100 mg/kg-bw/d for F₀ systemic toxicity and female reproductive toxicity, 300 mg/kg-bw/d for F₀ male reproductive toxicity, and 100 mg/kg-bw/d for F₁ neonatal and F₁ generation toxicity.

Oral toxicity evaluation of cannabidiol

Use of cannabidiol (CBD) in humans has increased considerably in recent years. While currently available studies suggest that CBD is relatively safe for human consumption, data from publicly available studies on CBD conducted according to modern testing guidelines are lacking. In the current study, the potential for toxicity following repeated oral exposure to hemp-derived CBD isolate was evaluated in male and female Sprague Dawley rats. No adverse treatment-related effects were observed following administration of CBD via oral gavage for 14 and 90 days at concentrations up to 150 and 140 mg/kg-bw/d, respectively. Microscopic liver and adrenal gland changes observed in the 90-day study were determined to be resolved after a 28-day recovery period. CBD was well tolerated at these dose levels, and the results of this study are comparable to findings reported in unpublished studies conducted with other CBD isolates. The current studies were conducted as part of a broader research program to examine the safety of CBD.

Development and validation of a sensitive assay for the quantification of arachidonoylcyclopropylamide (ACPA) in cell culture by LC–MS/MS

Synthetic and natural cannabinoid derivatives are highly investigated as drug candidates due to their antinociceptive, antiepileptic and anticancer potential. Arachidonoylcyclopropylamide (ACPA) is a synthetic cannabinoid with antiproliferative and apoptotic effects on non-small cell lung cancer and pancreatic and endometrial carcinoma. Thus, ACPA has a great potential for being used as an anticancer drug for epithelial cancers. Therefore, determining the levels of ACPA in biological fluids, cells, tissues and pharmaceutical dosage forms is crucial in monitoring the effects of various pharmacological, physiological and pathological stimuli on biological systems. However, the challenge in the quantification of ACPA is its short half-life and lack of UV signal. Therefore, we developed a liquid chromatography-tandem mass spectrometric (LC–MS/MS) method for sensitive and selective quantification of ACPA in cell culture medium and intracellular matrix. Multiple reaction monitoring in the positive ionization mode was used for detection with 344 → 203 m/z transitions. The separation of ACPA was performed on C18 column (50 × 3.0 mm, 2.1 μm) with the mobile phase run in the gradient mode with 0.1% formic acid (FA) in water and 0.1% FA in acetonitrile at a flow rate of 0.3 ml/min. The assay was linear in the concentration range of 1.8–1000 ng/mL (r = 0.999). The validation studies revealed that the method was linear, sensitive, accurate, precise, selective, repeatable, robust and rugged. Finally, the developed method was applied to quantify ACPA in cell culture medium and intracellular matrix.

Cannabis use amongst tinnitus patients: consumption patterns and attitudes

BACKGROUND

Tinnitus has a significant impact on quality of life and causes considerable psychological distress. Cannabis is known to modulate neuron hyperexcitability, provide protection against auditory damage, and has been used for treatment for many diseases which have physiological similarities with tinnitus. The objective of this study was to survey patients presenting with tinnitus regarding their perspectives and usage patterns of cannabis.

METHODS

Patients with a primary presenting complaint of tinnitus in a tertiary neuro-otology clinic completed a 18-item questionnaire assessing perception, attitudes, and cannabis usage patterns.

RESULTS

Forty five patients completed the survey (mean age: 54.5 years, 31 females and 14 males). Overall, 96% of patients reported that they would consider cannabis as treatment for their tinnitus. Patients considered cannabis use for auditory symptoms (91%), and symptoms related to their tinnitus, such as emotional complaints (60%), sleep disturbances (64%), and functional disturbances (56%). 36% of patients had previously used cannabis and 22% of patients reported cannabis use at the time of the study. 80% of patients that were actively using cannabis reported that it helped with tinnitus-related symptoms, such as dizziness, anxiety, bodily pain, and sleep disturbances. Most patients would prefer to use edibles (62%), tablet (58%) and cream (47%) formulations of cannabis. Patients were concerned about the cost (29%), potential physical health implications (53%) and psychosocial side effects (60%) of cannabis. Over half of patients learned about cannabis from a friend or family member and only 22% of patients learned about cannabis from a physician or nurse.

CONCLUSION

Cannabis use is common amongst patients with tinnitus and current users of cannabis reported that it helped with their symptoms. Most patients would consider its use as a potential treatment to alleviate their tinnitus-related symptoms and are interested in learning more regarding its use. By understanding how cannabis is perceived by tinnitus patients, healthcare providers can provide appropriate patient education.

Therapeutic and clinical foundations of cannabidiol therapy for difficult-to-treat seizures in children and adults with refractory epilepsies

Novel and effective antiseizure medications are needed to treat refractory and rare forms of epilepsy. Cannabinoids, which are obtained from the cannabis plant, have a long history of medical use, including for neurologic conditions. In 2018, the US Food and Drug Administration approved the first phytocannabinoid, cannabidiol (CBD, Epidiolex), which is now indicated for severe seizures associated with three rare forms of developmental and epileptic encephalopathy: Dravet syndrome, Lennox-Gastaut syndrome, and tuberous sclerosis complex. Compelling evidence supports the efficacy of CBD in experimental models and patients with epilepsy. In randomized clinical trials, highly-purified CBD has demonstrated efficacy with an acceptable safety profile in children and adults with difficult-to-treat seizures. Although the underlying antiseizure mechanisms of CBD in humans have not yet been elucidated, the identification of novel antiseizure targets of CBD preclinically indicates multimodal mechanisms that include non-cannabinoid pathways. In addition to antiseizure effects, CBD possesses strong anti-inflammatory and neuroprotective activities, which might contribute to protective effects in epilepsy and other conditions. This article provides a succinct overview of therapeutic approaches and clinical foundations of CBD, emphasizing the clinical utility of CBD for the treatment of seizures associated with refractory and rare epilepsies. CBD has shown to be a safe and effective antiseizure medicine, demonstrating a broad spectrum of efficacy across multiple seizure types, including those associated with severe epilepsies with childhood onset. Despite such promise, there are many perils with CBD that hampers its widespread use, including limited understanding of pharmacodynamics, limited exposure-response relationship, limited information for seizure freedom with continued use, complex pharmacokinetics with drug interactions, risk of adverse effects, and lack of expert therapeutic guidelines. These scientific issues need to be resolved by further investigations, which would decide the unique role of CBD in the management of refractory epilepsy.

Endocannabinoid signaling in brain diseases: Emerging relevance of glial cells

The discovery of cannabinoid receptors as the primary molecular targets of psychotropic cannabinoid Δ⁹ -tetrahydrocannabinol (Δ⁹ -THC) in late 1980s paved the way for investigations on the effects of cannabis-based therapeutics in brain pathology. Ever since, a wealth of results obtained from studies on human tissue samples and animal models have highlighted a promising therapeutic potential of cannabinoids and endocannabinoids in a variety of neurological disorders. However, clinical success has been limited and major questions concerning endocannabinoid signaling need to be satisfactorily addressed, particularly with regard to their role as modulators of glial cells in neurodegenerative diseases. Indeed, recent studies have brought into the limelight diverse, often unexpected functions of astrocytes, oligodendrocytes, and microglia in brain injury and disease, thus providing scientific basis for targeting glial cells to treat brain disorders. This Review summarizes the current knowledge on the molecular and cellular hallmarks of endocannabinoid signaling in glial cells and its clinical relevance in neurodegenerative and chronic inflammatory disorders.

Cannabinoids as Prospective Anti-Cancer Drugs: Mechanism of Action in Healthy and Cancer Cells

Endogenous and exogenous cannabinoids modulate many physiological and pathological processes by binding classical cannabinoid receptors 1 (CB1) or 2 (CB2) or non-cannabinoid receptors. Cannabinoids are known to exert antiproliferative, apoptotic, anti-migratory and anti-invasive effect on cancer cells by inducing or inhibiting various signaling cascades. In this chapter, we specifically emphasize the latest research works about the alterations in endocannabinoid system (ECS) components in malignancies and cancer cell proliferation, migration, invasion, angiogenesis, autophagy, and death by cannabinoid administration, emphasizing their mechanism of action, and give a future perspective for clinical use.

Non-psychotropic phytocannabinoid interactions with voltage-gated sodium channels: An update on cannabidiol and cannabigerol

Phytocannabinoids, found in the plant, Cannabis sativa, are an important class of natural compounds with physiological effects. These compounds can be generally divided into two classes: psychoactive and non-psychoactive. Those which do not impart psychoactivity are assumed to predominantly function via endocannabinoid receptor (CB) -independent pathways and molecular targets, including other receptors and ion channels. Among these targets, the voltage-gated sodium (Nav) channels are particularly interesting due to their well-established role in electrical signalling in the nervous system. The interactions between the main non-psychoactive phytocannabinoid, cannabidiol (CBD), and Nav channels were studied in detail. In addition to CBD, cannabigerol (CBG), is another non-psychoactive molecule implicated as a potential therapeutic for several conditions, including pain via interactions with Nav channels. In this mini review, we provide an update on the interactions of Nav channels with CBD and CBG.

Persistent Diarrhea and Eosinophilic Esophagitis Resulting From Chronic Cannabidiol Usage for Refractory Epilepsy

Cannabidiol is used in the care of treatment-resistant epilepsy. It has been associated with varying side effects, ranging from somnolence to diarrhea and weight loss. We present a patient on chronic cannabidiol therapy who had persistent diarrhea, abdominal pain, weight loss, and esophageal eosinophilia that improved with cannabidiol dose adjustment.

Current and future pharmacotherapy options for drug-resistant epilepsy

INTRODUCTION

Epilepsy is one of the most common and serious neurological conditions, affecting over 70 million individuals worldwide and despite advances in treatment, the proportion of drug-resistant patients has remained largely unchanged.

AREAS COVERED

The present paper reviews current and future (under preclinical and clinical development) pharmacotherapy options for the treatment of drug-resistant focal and generalized epilepsies.

EXPERT OPINION

Current pharmacotherapy options for drug-resistant epilepsy include perampanel, brivaracetam and the newly approved cenobamate for focal epilepsies; cannabidiol (Epidiolex) for Lennox-Gastaut Syndrome (LGS), Dravet and Tuberous Sclerosis Complex (TSC); fenfluramine for Dravet syndrome and ganaxolone for seizures in Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder. Many compounds are under clinical development and may hold promise for future pharmacotherapies. For adult focal epilepsies, padsevonil and carisbamate are at a more advanced Phase III stage of clinical development followed by compounds at Phase II like selurampanel, XEN1101 and JNJ-40411813. For specific epilepsy syndromes, XEN 496 is under Phase III development for potassium voltage-gated channel subfamily Q member 2 developmental and epileptic encephalopathy (KCNQ2-DEE), carisbamate is under Phase III development for LGS and Ganaxolone under Phase III development for TSC. Finally, in preclinical models several molecular targets including inhibition of glycolysis, neuroinflammation and sodium channel inhibition have been identified in animal models although further data in animal and later human studies are needed.

Neuroprotection of Cannabidiol, Its Synthetic Derivatives and Combination Preparations against Microglia-Mediated Neuroinflammation in Neurological Disorders

The lack of effective treatment for neurological disorders has encouraged the search for novel therapeutic strategies. Remarkably, neuroinflammation provoked by the activated microglia is emerging as an important therapeutic target for neurological dysfunction in the central nervous system. In the pathological context, the hyperactivation of microglia leads to neuroinflammation through the release of neurotoxic molecules, such as reactive oxygen species, proteinases, proinflammatory cytokines and chemokines. Cannabidiol (CBD) is a major pharmacologically active phytocannabinoids derived from Cannabis sativa L. CBD has promising therapeutic effects based on mounting clinical and preclinical studies of neurological disorders, such as epilepsy, multiple sclerosis, ischemic brain injuries, neuropathic pain, schizophrenia and Alzheimer's disease. A number of preclinical studies suggested that CBD exhibited potent inhibitory effects of neurotoxic molecules and inflammatory modulators, highlighting its remarkable therapeutic potential for the treatment of numerous neurological disorders. However, the molecular mechanisms of action underpinning CBD's effects on neuroinflammation appear to be complex and are poorly understood. This review summarises the anti-neuroinflammatory activities of CBD against various neurological disorders with a particular focus on their main molecular mechanisms of action, which were related to the downregulation of NADPH oxidase-mediated ROS, TLR4-NFκB and IFN-β-JAK-STAT pathways. We also illustrate the pharmacological action of CBD's derivatives focusing on their anti-neuroinflammatory and neuroprotective effects for neurological disorders. We included the studies that demonstrated synergistic enhanced anti-neuroinflammatory activity using CBD and other biomolecules. The studies that are summarised in the review shed light on the development of CBD, including its derivatives and combination preparations as novel therapeutic options for the prevention and/or treatment of neurological disorders where neuroinflammation plays an important role in the pathological components.

Cannabidiol for the treatment of refractory epilepsy in children: a critical review of the literature

Objective:

The aim of this current report was to present a critical review of the use of cannabidiol (CBD) in the treatment of refractory epilepsies in the pediatric population.

Data source:

Literature review was carried out in the Medline (PubMed), Cochrane, and Scientific Electronic Library Online (SciELO) databases with the descriptors “Cannabidiol” and “Epilepsy.” The search was not limited by the date of publication, language, or study design. A total of 69 articles were included in the review.

Data synthesis:

The efficacy of CBD in treating epileptic seizures has been confirmed by randomized controlled trials for Lennox–Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex. The incidence of side effects reported in subjects of the studies is high. However, most studies indicate a good safety profile and tolerance to the drug, with most of the adverse effects being mild to moderate and transient.

Conclusions:

There is no consensus on the release of CBD as a therapeutic tool by the drug regulatory agencies worldwide. However, the use of CBD is promising since it has presented satisfactory results in crisis control in well-designed studies. In addition, this drug has a good safety and tolerance profile. However, further studies with a long follow-up period are needed to confirm its usefulness and the long-term safety in pediatric patients.

Current Principles in the Management of Drug-Resistant Epilepsy

Drug-resistant epilepsy is associated with poor health outcomes and increased economic burden. In the last three decades, various new antiseizure medications have been developed, but the proportion of people with drug-resistant epilepsy remains relatively unchanged. Developing strategies to address drug-resistant epilepsy is essential. Here, we define drug-resistant epilepsy and emphasize its relationship to the conceptualization of epilepsy as a symptom complex, delineate clinical risk factors, and characterize mechanisms based on current knowledge. We address the importance of ruling out pseudoresistance and consider the impact of nonadherence on determining whether an individual has drug-resistant epilepsy. We then review the principles of epilepsy drug therapy and briefly touch upon newly approved and experimental antiseizure medications.

Between Science and Big Business: Tapping Mary Jane's Uncharted Potential

At the intersection of science and medicine, government policy, and pop culture, cannabis has prompted society since the beginning of recorded history. And yet, there is comparatively little replicable data on the plant, its constituents, and their capacity to modify human physiology. Over the past decades, several findings have pointed toward the importance of the endogenous cannabinoid system in maintaining homeostasis, making it an important target for various diseases. Here, we summarize the current state of knowledge on endogenous- and plant-based cannabinoids, address the issues related to cannabinoid-based drug discovery, and incite efforts to utilize their polypharmacological profile toward tackling diseases with a complex underlying pathophysiology. By fusing modern science and technology with the empirical data that has been gathered over centuries, we propose an outlook that could help us overcome the dearth of innovation for new drugs and synchronously redefine the future of drug discovery. Simultaneously, we call attention to the startling disconnect between the scientific, regulatory, and corporate entities that is becoming increasingly evident in this booming industry.

A scoping review of the use of cannabidiol in psychiatric disorders

Cannabidiol (CBD) has become a fast-growing avenue for research in psychiatry, and clinicians are challenged with understanding the implications of CBD for treating mental health disorders. The goal of this review is to serve as a guide for mental health professionals by providing an overview of CBD and a synthesis the current evidence within major psychiatric disorders. PubMed and PsycINFO were searched for articles containing the terms "cannabidiol" in addition to major psychiatric disorders and symptoms, yielding 2952 articles. Only randomized controlled trials or within-subject studies investigating CBD as a treatment option for psychiatric disorders (N = 16) were included in the review. Studies were reviewed for psychotic disorders (n = 6), anxiety disorders (n = 3), substance use disorders (tobacco n = 3, cannabis n = 2, opioid n = 1), and insomnia (n = 1). There were no published studies that met inclusion criteria for alcohol or stimulant use disorder, PTSD, ADHD, autism spectrum disorder, or mood disorders. Synthesis of the CBD literature indicates it is generally safe and well tolerated. The most promising preliminary findings are related to the use of CBD in psychotic symptoms and anxiety. There is currently not enough high-quality evidence to suggest the clinical use of CBD for any psychiatric disorder.

An Evaluation of Understudied Phytocannabinoids and Their Effects in Two Neuronal Models

Cannabis contains more than 100 phytocannabinoids. Most of these remain poorly characterized, particularly in neurons. We tested a panel of five phytocannabinoids-cannabichromene (CBC), cannabidiolic acid (CBDA), cannabidivarin (CBDV), cannabidivarinic acid (CBDVA), and Δ9-tetrahydrocannabivarin (THCV) in two neuronal models, autaptic hippocampal neurons and dorsal root ganglion (DRG) neurons. Autaptic neurons expressed a form of CB1-dependent retrograde plasticity while DRGs expressed a variety of transient receptor potential (TRP) channels. CBC, CBDA, and CBDVA had little or no effect on neuronal cannabinoid signaling. CBDV and THCV differentially inhibited cannabinoid signaling. THCV inhibited CB1 receptors presynaptically while CBDV acted post-synaptically, perhaps by inhibiting 2-AG production. None of the compounds elicited a consistent DRG response. In summary, we find that two of five 'minor' phytocannabinoids tested antagonized CB1-based signaling in a neuronal model, but with very different mechanisms. Our findings highlight the diversity of potential actions of phytocannabinoids and the importance of fully evaluating these compounds in neuronal models.

Design of Negative and Positive Allosteric Modulators of the Cannabinoid CB2 Receptor Derived from the Natural Product Cannabidiol

Cannabidiol (CBD), the second most abundant of the active compounds found in the Cannabis sativa plant, is of increasing interest because it is approved for human use and is neither euphorizing nor addictive. Here, we design and synthesize novel compounds taking into account that CBD is both a partial agonist, when it binds to the orthosteric site, and a negative allosteric modulator, when it binds to the allosteric site of the cannabinoid CB₂ receptor. Molecular dynamic simulations and site-directed mutagenesis studies have identified the allosteric site near the receptor entrance. This knowledge has permitted to perform structure-guided design of negative and positive allosteric modulators of the CB₂ receptor with potential therapeutic utility.

Cannabidiol and Sodium Channel Pharmacology: General Overview, Mechanism, and Clinical Implications

Voltage-gated sodium (Nav) channels initiate action potentials in excitable tissues. Altering these channels' function can lead to many pathophysiological conditions. Nav channels are composed of several functional and structural domains that could be targeted pharmacologically as potential therapeutic means against various neurological conditions. Mutations in Nav channels have been suggested to underlie various clinical syndromes in different tissues and in association with conditions ranging from epileptic to muscular problems. Treating those mutations that increase the excitability of Nav channels requires inhibitors that could effectively reduce channel firing. The main non-psychotropic constituent of the cannabis plant, cannabidiol (CBD), has recently gained interest as a viable compound to treat some of the conditions that are associated with Nav malfunctions. In this review, we discuss an overview of Nav channels followed by an in-depth description of the interactions of CBD and Nav channels. We conclude with some clinical implications of CBD use against Nav hyperexcitability based on a series of preclinical studies published to date, with a focus on Nav/CBD interactions.

U.S. FDA Approved Drugs from 2015-June 2020: A Perspective

In the present work, we report compilation and analysis of 245 drugs, including small and macromolecules approved by the U.S. FDA from 2015 until June 2020. Nearly 29% of the drugs were approved for the treatment of various types of cancers. Other major therapeutic areas of focus were infectious diseases (14%); neurological conditions (12%); and genetic, metabolic, and cardiovascular disorders (7-8% each). Itemization of the approved drugs according to the year of approval, sponsor, target, chemical class, major drug-metabolizing enzyme(s), route of administration/elimination, and drug-drug interaction liability (perpetrator or/and victim) is presented and discussed. An effort has been made to analyze the pharmacophores to identify the structural (e.g., aromatic, heterocycle, and aliphatic), elemental (e.g., boron, sulfur, fluorine, phosphorus, and deuterium), and functional group (e.g., nitro drugs) diversity among the approved drugs. Further, descriptor-based chemical space analysis of FDA approved drugs and several strategies utilized for optimizing metabolism leading to their discoveries have been emphasized. Finally, an analysis of drug-likeness for the approved drugs is presented.

Emerging Roles of Cannabinoids and Synthetic Cannabinoids in Clinical Experimental Models

In recent years, an increasing number of investigations has demonstrated the therapeutic potential of molecules targeting the endocannabinoid system. Cannabinoids of endogenous, phytogenic, and synthetic nature have been assessed in a wide variety of disease models ranging from neurological to metabolic disorders. Even though very few compounds of this type have already reached the market, numerous preclinical and clinical studies suggest that cannabinoids are suitable drugs for the clinical management of diverse pathologies.In this chapter, we will provide an overview of the endocannabinoid system under certain physiopathological conditions, with a focus on neurological, oncologic, and metabolic disorders. Cannabinoids evaluated as potential therapeutic agents in experimental models with an emphasis in the most successful chemical entities and their perspectives towards the clinic will be discussed.

Cannabidiol Therapy for Refractory Epilepsy and Seizure Disorders

Cannabis-derived cannabinoids have neuroactive properties. Recently, there has been emerging interest in the use of cannabidiol (CBD)-enriched products for treatment of drug-resistant epilepsy. In 2018, the FDA approved the use of CBD-rich Epidiolex for two severe forms of epilepsy in children (Lennox-Gastaut and Dravet syndromes). Experimental research supports the use of CBD in many CNS disorders, though the mechanisms underlying its anticonvulsant and neuroprotective effects remain unclear. CBD has been shown to reduce inflammation, protect against neuronal loss, normalize neurogenesis, and act as an antioxidant. These actions appear to be due to the multimodal mechanism of action of CBD in the brain. This chapter briefly describes the current information on cannabis pharmacology with an emphasis on the clinical utility of CBD in the treatment of refractory epilepsies and other related seizure conditions. Clinical trials are ongoing for other forms of epilepsy and refractory seizures associated with infantile spasms, tuberous sclerosis, and Rett syndrome. Overall, adjunct CBD has been found to be generally safe and effective for treatment-resistant seizures in children with severe early-onset epilepsy. Whether an add-on CBD is efficacious for the long-term treatment of various epilepsy and seizure types in adults being tested in various clinical trials.

Cannabidiol reduces soman-induced lethality and seizure severity in female plasma carboxylesterase knockout mice treated with midazolam

Cannabidiol, approved for treatment of pediatric refractory epilepsy, has anti-seizure effects in various animal seizure models. Chemical warfare nerve agents, including soman, are organophosphorus chemicals that can induce seizure and death if untreated or if treatment is delayed. Our objective was to evaluate whether cannabidiol would ameliorate soman-induced toxicity using a mouse model that similar to humans lacks plasma carboxylesterase. In the present study, adult female plasma carboxylesterase knockout (Es1-/-) mice were pre-treated with cannabidiol (20-150 mg/kg) or vehicle 1 h prior to exposure to a seizure-inducing dose of soman and evaluated for survival and seizure activity. The muscarinic antagonist atropine sulfate and the oxime HI-6 were administered at 1 min after exposure, and the benzodiazepine midazolam was administered at 30 min after seizure onset. Cannabidiol (150 mg/kg) pre-treatment led to a robust increase in survival rate and attenuated body weight loss in soman-exposed mice treated with medical countermeasures, compared to mice pre-treated with vehicle. In addition, mice pretreated with cannabidiol (150 mg/kg) had a modest reduction in seizure severity after midazolam treatment compared to vehicle-pretreated. These findings of improved outcome with cannabidiol administration in a severe seizure model of soman exposure provide additional pre-clinical support for the benefits of cannabidiol against exposure to seizure-inducing chemical agents and suggest cannabidiol may augment the anti-seizure effects of midazolam.

Cannabinoids, Inner Ear, Hearing, and Tinnitus: A Neuroimmunological Perspective

Cannabis has been used for centuries for recreational and therapeutic purposes. Whereas, the recreative uses are based on the psychotropic effect of some of its compounds, its therapeutic effects range over a wide spectrum of actions, most of which target the brain or the immune system. Several studies have found cannabinoid receptors in the auditory system, both at peripheral and central levels, thus raising the interest in cannabinoid signaling in hearing, and especially in tinnitus, which is affected also by anxiety, memory, and attention circuits where cannabinoid effects are well described. Available studies on animal models of tinnitus suggest that cannabinoids are not likely to be helpful in tinnitus treatment and could even be harmful. However, the pharmacology of cannabinoids is very complex, and most studies focused on neural CB1R-based responses. Cannabinoid effects on the immune system (where CB2Rs predominate) are increasingly recognized as essential in understanding nervous system pathological responses, and data on immune cannabinoid targets have emerged in the auditory system as well. In addition, nonclassical cannabinoid targets (such as TRP channels) appear to play an important role in the auditory system as well. This review will focus on neuroimmunological mechanisms for cannabinoid effects and their possible use as protective and therapeutic agents in the ear and auditory system, especially in tinnitus.

The Endocannabinoid System Activation as a Neural Network Desynchronizing Mediator for Seizure Suppression

The understanding that hyper-excitability and hyper-synchronism in epilepsy are indissociably bound by a cause-consequence relation has only recently been challenged. Thus, therapeutic strategies for seizure suppression have often aimed at inhibiting excitatory circuits and/or activating inhibitory ones. However, new approaches that aim to desynchronize networks or compromise abnormal coupling between adjacent neural circuitry have been proven effective, even at the cost of enhancing local neuronal activation. Although most of these novel perspectives targeting circuitry desynchronization and network coupling have been implemented by non-pharmacological devices, we argue that there may be endogenous neurochemical systems that act primarily in the desynchronization component of network behavior rather than dampening excitability of individual neurons. This review explores the endocannabinoid system as one such possible pharmacological landmark for mimicking a form of "on-demand" desynchronization analogous to those proposed by deep brain stimulation in the treatment of epilepsy. This essay discusses the evidence supporting the role of the endocannabinoid system in modulating the synchronization and/or coupling of distinct local neural circuitry; which presents obvious implications on the physiological setting of proper sensory-motor integration. Accordingly, the process of ictogenesis involves pathological circuit coupling that could be avoided, or at least have its spread throughout the containment of other areas, if such endogenous mechanisms of control could be activated or potentiated by pharmacological intervention. In addition, we will discuss evidence that supports not only a weaker role played on neuronal excitability but the potential of the endocannabinoid system strengthening its modulatory effect, only when circuitry coupling surpasses a level of activation.

Structural Insights into β-arrestin/CB1 Receptor Interaction: NMR and CD Studies on Model Peptides

Activation of the cannabinoid CB1 receptor induces different cellular signaling cascades through coupling to different effector proteins (G-proteins and β-arrestins), triggering numerous therapeutic effects. Conformational changes and rearrangements at the intracellular domain of this GPCR receptor that accompany ligand binding dictate the signaling pathways. The GPCR-binding interface for G proteins has been extensively studied, whereas β-arrestin/GPCR complexes are still poorly understood. To gain knowledge in this direction, we designed peptides that mimic the motifs involved in the putative interacting region: β-arrestin1 finger loop and the transmembrane helix 7-helix 8 (TMH7-H8) elbow located at the intracellular side of the CB1 receptor. According to circular dichroism and NMR data, these peptides form a native-like, helical conformation and interact with each other in aqueous solution, in the presence of trifluoroethanol, and using zwitterionic detergent micelles as membrane mimics. These results increase our understanding of the binding mode of β-arrestin and CB1 receptor and validate minimalist approaches to structurally comprehend complex protein systems.

Plant-derived natural therapeutics targeting cannabinoid receptors in metabolic syndrome and its complications: A review

The endocannabinoid system (ECS) is natural physiological system in the humans. The presence of the ECS system involves different roles in body. The endocannabinoid system involves regulation of most of the centers, which regulates the hunger and leads to changes in the weight. In the present article, we reviewed the role of natural cannabinoid compounds in metabolic disorders and related complications. We studied variety of a plant-derived cannabinoids in treating the metabolic syndrome including stoutness, fatty acid liver diseases, insulin obstruction, dementia, hypertension, lipid abnormalities, non-alcoholic steatohepatitis, endothelial damage, and polycystic ovarian syndrome and so on. The activation of cannabinoid receptors demonstrates a significant number of beneficial approaches concerning metabolic syndrome and reduces the pro-inflammatory cytokines on account of aggravation, decreased oxidative stress and uneasiness, diminishes liver fibrosis, with reduces adiponectin. Pre-clinical investigations of plant-derived cannabinoids resulted in promising outcomes. The different distinctive plant-derived cannabinoids were discovered like cannabidiol (CBD), cannabinol (CBN), cannabichromene (CBC), and cannabidiol (CBG). It has been observed that endogenous cannabinoids and plant-derived cannabinoids have an advantageous impact on limiting the metabolic disorder arising due to lifestyle changes.

Cannabidiol Partially Blocks the Excessive Sleepiness in Hypocretindeficient Rats: Preliminary Data

BACKGROUND

Excessive daytime sleepiness and cataplexy are among the symptoms of narcolepsy, a sleep disorder caused by the loss of hypocretin/orexin (HCRT/OX) neurons placed into the Hypothalamus (LH). Several treatments for managing narcolepsy include diverse drugs to induce alertness, such as antidepressants, amphetamine, or modafinil, etc. Recent evidence has shown that cannabidiol (CBD), a non-psychotropic derived from Cannabis sativa, shows positive therapeutic effects in neurodegenerative disorders, including Parkinson´s disease. Furthermore, CBD provokes alertness and enhances wake-related neurochemicals in laboratory animals. Thus, it is plausible to hypothesize that excessive somnolence observed in narcolepsy might be blocked by CBD.

OBJECTIVE

Here, we determined whether the systemic injection of CBD (5mg/kg, i.p.) would block the excessive sleepiness in a narcoleptic model.

METHODS

To test this idea, the neurotoxin hypocretin-2-saporin (HCRT2/SAP) was bilaterally injected into the LH of rats to eliminate HCRT leading to the establishment of narcoleptic-like behavior. Since excessive somnolence in HCRT2/SAP lesioned rats has been observed during the lights-off period, CBD was administered at the beginning of the dark phase.

RESULTS

Hourly analysis of sleep data showed that CBD blocked the sleepiness during the lights-off period across 7h post-injection in lesioned rats.

CONCLUSION

Taking together, these preliminary findings suggest that CBD might prevent sleepiness in narcolepsy.

Use of Cannabidiol for the Treatment of Anxiety: A Short Synthesis of Pre-Clinical and Clinical Evidence

Anxiety disorders have the highest lifetime prevalence of any mental illness worldwide, leading to high societal costs and economic burden. Current pharmacotherapies for anxiety disorders are associated with adverse effects and low efficacy. Cannabidiol (CBD) is a constituent of the Cannabis plant, which has potential therapeutic properties for various indications. After the recent legalization of cannabis, CBD has drawn increased attention as a potential treatment, as the majority of existing data suggest it is safe, well tolerated, has few adverse effects, and demonstrates no potential for abuse or dependence in humans. Pre-clinical research using animal models of innate fear and anxiety-like behaviors have found anxiolytic, antistress, anticompulsive, and panicolytic-like effects of CBD. Preliminary evidence from human trials using both healthy volunteers and individuals with social anxiety disorder, suggests that CBD may have anxiolytic effects. Although these findings are promising, future research is warranted to determine the efficacy of CBD in other anxiety disorders, establish appropriate doses, and determine its long-term efficacy. The majority of pre-clinical and clinical research has been conducted using males only. Among individuals with anxiety disorders, the prevalence rates, symptomology, and treatment response differ between males and females. Thus, future research should focus on this area due to the lack of research in females and the knowledge gap on sex and gender differences in the effectiveness of CBD as a potential treatment for anxiety.

Novel approaches and current challenges with targeting the endocannabinoid system

INTRODUCTION

The pathophysiological relevance of the endocannabinoid system has been widely demonstrated in a variety of diseases including cancer, neurological disorders, and metabolic issues. Therefore, targeting the receptors and the endogenous machinery involved in this system can provide a successful therapeutic outcome. Ligands targeting the canonical cannabinoid receptors, CB1 and CB2, along with inhibitors of the endocannabinoid enzymes have been thoroughly studied in diverse disease models. In fact, phytocannabinoids such as cannabidiol or Δ9-tetrahydrocannabinol are currently on the market for the management of neuropathic pain due to spasticity in multiple sclerosis or seizures in children epilepsy amongst others.

AREAS COVERED

Challenges in the pharmacology of cannabinoids arise from its pharmacokinetics, off-target effects, and psychoactive effects. In this context, the current review outlines the novel molecular approaches emerging in the field discussing their clinical potential.

EXPERT OPINION

Even if orthosteric CB1 and CB2 ligands are on the forefront in cannabinoid clinical research, emerging strategies such as allosteric or biased modulation of these receptors along with controlled off-targets effects may increase the therapeutic potential of cannabinoids.

Cannabis Treatment in Children with Epilepsy: Practices of Canadian Neurologists

BACKGROUND

Medical cannabis has recently emerged as a treatment option for children with drug-resistant epilepsy. Despite the fact that many pediatric epilepsy patients across Canada are currently being treated with cannabis, little is known about the attitudes of neurologists toward cannabinoid treatment of children with epilepsy.

METHODS

A 21-item online survey was distributed via email to 148 pediatric neurologists working in hospitals and community clinics across Canada. Questions were related to clinical practice and demographics.

RESULTS

This survey achieved a response rate of 38% (56 Canadian neurologists). These neurologists were treating 668 pediatric epilepsy patients with cannabinoids. While 29% of neurologists did not support cannabis treatment in their patients, 34% prescribed cannabis, and 38% referred to another authorizing physician, mostly to community-based non-neurologists. The majority of neurologists considered cannabis for patients with Dravet syndrome (68%) and Lennox-Gastaut syndrome (64%) after an average of three failed anticonvulsants. Twenty-seven percent considered it for patients with idiopathic generalized epilepsy, and 18% for focal epilepsy. No neurologist used cannabis as a first-line treatment. All neurologists had at least one hesitation regarding cannabis treatment in pediatric epilepsy. The most common one was poor evidence (66%), followed by poor quality control (52%) and high cost (50%).

CONCLUSIONS

The majority of Canadian pediatric neurologists consider using cannabis as a treatment for epilepsy in children. With many gaps in evidence and high patient-driven demand for cannabis therapy, this survey provides immediate information from the "wisdom of the crowd," to aid neurologists until further evidence is available.

[Dependence and Cytotoxicity of Components of Cannabis]

Cannabis use among the younger population in Japan has been steadily increasing. The aim of the present review is to highlight recent knowledge regarding the molecular mechanisms of action and health risks associated with cannabis and synthetic cannabinoid consumption. We investigated the effects of Δ⁹-tetrahydrocannabinol (THC) and synthetic cannabinoids on place conditioning in ICR mice. Both Δ⁹-THC and synthetic cannabinoids produce a significant conditioned place preference. These rewarding effects were completely suppressed by the cannabinoid CB₁ receptor type antagonist AM251. The cytotoxicological effects of Δ⁹-THC and synthetic cannabinoids were also characterized in the limbic forebrain of mice in primary culture in vitro. Δ⁹-THC and synthetic cannabinoids caused cell death in a dose-dependent manner. The rank order of cytotoxicological potency was synthetic cannabinoids>Δ⁹-THC and related to the agonistic activities of the CB₁ receptor. A recent review on the harmful effects of cannabis use in humans reported that behavioral impairments, especially in terms of attention, memory, and complex information-processing ability, can last for many weeks after cessation of cannabis use among heavy users. In addition, cannabis use could be a risk factor for drug dependence and later psychosis among adolescents. The results of animal and human studies suggest that CB₁ receptors play an important role in the expression of harmful effects of cannabis and synthetic cannabinoid use. Moreover, concern regarding increasing concentrations of Δ⁹-THC in cannabis in many countries has been noted, because more potent cannabis may be associated with worse adverse effects.

Antiepileptic Drugs in Pediatrics

Epilepsy affects approximately 1% of the population. First-line treatment for epilepsy is the administration of anti-seizure medication, also referred to as antiepileptic drugs (AEDs), although this nomenclature is erroneous as these medications typically do not impact underlying epileptogenic processes; the goal of these medications is to control symptoms. Over 30% of patients are classified as having "medically refractory" epilepsy, i.e., lack of adequate seizure control despite trials of two or three AEDs (Kwan and Brodie, N Engl J Med 342:314-9, 2000). Epilepsy is associated with worse quality of life in children, adolescents, and their families (Cianchetti et al., Seizure 24:93-101, 2015). Patients with epilepsy have a two to three times greater risk of death than the general population, by various causes including sudden unexplained death in epilepsy patients (SUDEP) (Abdel-Mannan et al., Epilepsy Behav 90:99-106, 2019). It is these factors, among others, that have motivated the continued development of AEDs. This chapter will review the history and evolution of AED development, features of specific AEDs with a focus on the newest generation, and examples of AEDs in development.

Cannabinoids and dystonia: an issue yet to be defined

Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal movements and postures. Besides motor manifestations, patients with dystonia also display non-motor signs and symptoms including psychiatric and sensory disturbances. Symptomatic treatment of motor signs in dystonia largely relies on intramuscular botulinum toxin injections and, in selected cases, on deep brain stimulation. Oral medications and physical therapy offer a few benefits only in a minority of patients. Cannabinoids have been shown to be a complementary treatment in several neurological disorders but their usefulness in dystonia have not been systematically assessed. Given recent policy changes in favor of cannabis use in clinical practice and the request for alternative treatments, it is important to understand how cannabinoids may impact people with dystonia. Reviewing the evidence so far available and our own experience, cannabinoids seem to be effective in single cases but further studies are required to improve our understanding on their role as complementary treatment in dystonia.