Improved Bioavailability with Dry Powder Cannabidiol Inhalation: A Phase 1 Clinical Study

High-loading cannabidiol powders for inhalation

Limited attempts have been made previously to develop high-loading CBD inhalable powders, which are essential for high dose delivery. Therefore, this study aimed to develop and characterise inhalable powders with ≥ 95 % w/w CBD by wet ball milling. The effects of magnesium stearate (2 % and 5 %) and inhaler resistance (low-resistance and high-resistance RS01 inhalers) on aerosol performance were also compared. Wet ball milling produced CBD powders with > 50 % production yield. The milled particles showed irregular shapes. The powders were crystalline with minimal amorphous content, low residual solvent level (<1%), and low moisture sorption (<4%). Magnesium stearate improved both the emitted and fine particle fractions. The aerodynamic particle size distribution of the formulations differed between the low-resistance and high-resistance RS01 inhalers. The latter decreased throat deposition but increased inhaler retention. The dissolution profiles showed that all three formulations released CBD steadily and plateaued at 30 min. The best scenario was CBD with 5 % magnesium stearate dispersed from the high resistance RS01 inhaler, showing the highest FPF with the lowest throat deposition. This combination may be tested in vivo in the future to investigate its pharmacokinetic profile.

Cannabidiol: Pharmacodynamics and pharmacokinetic in the context of neuropsychiatric disorders

In this chapter we explored the growing interest in cannabinoids, particularly cannabidiol (CBD), over the last two decades due to their potential therapeutic applications in neurodegenerative and psychiatric disorders. CBD, a major non-psychotomimetic compound derived from Cannabis sativa, is highlighted as a safer alternative to other cannabinoids like Δ9-tetrahydrocannabinol (THC). Clinical trials have been investigating CBD formulations for conditions such as schizophrenia, multiple sclerosis, Alzheimer's, Parkinson's diseases, and stress-related disorders. However, limited access to CBD-approved formulations primarily due to their high-cost and concerns about the quality of market-available products, challenges regulatory agencies globally. The pharmacokinetics of CBD, especially after oral administration, present challenges with erratic absorption and low bioavailability. CBD's "promiscuous" pharmacodynamics involve interactions with various targets beyond the endocannabinoid system, complicating precise dosing in therapeutic interventions. This chapter delves into CBD's dose-response curves, revealing complexities that pose challenges in clinical practice. Nanobiotechnology emerges as a promising solution, with recent developments showing improved bioavailability, stability, and reduced toxicity through nanoencapsulation of CBD. While this phytocannabinoid holds immense promise in neuropsychopharmacology, we provided a comprehensive overview of the current state of CBD research and suggests potential future directions regarding the pharmacology of CBD, harnessing the benefits of this intriguing compound.

Cannabidiol and its application in the treatment of oral diseases: therapeutic potentials, routes of administration and prospects

Cannabidiol (CBD), one of the most important active ingredients in cannabis, has been reported to have some pharmacological effects such as antibacterial and analgesic effects, and to have therapeutic potential in the treatment of oral diseases such as oral cancer, gingivitis and periodontal diseases. However, there is a lack of relevant systematic research and reviews. Therefore, based on the etiology and clinical symptoms of several common oral diseases, this paper focuses on the therapeutic potential of CBD in periodontal diseases, pulp diseases, oral mucosal diseases, oral cancer and temporomandibular joint diseases. The pharmacological effects of CBD and the distribution and function of its receptors in the oral cavity are also summarized. In order to provide reference for future research and further clinical application of CBD, we also summarize several possible routes of administration and corresponding characteristics. Finally, the challenges faced while applying CBD clinically and possible solutions are discussed, and we also look to the future.

Spray freeze dried cannabidiol with dipalmitoylphosphatidylcholine (DPPC) for inhalation and solubility enhancement

Pulmonary delivery is an efficient route of administration to deliver cannabidiol (CBD) due to the high bioavailability and fast onset of action. The major formulation challenge is the poor aqueous solubility of CBD. This study aimed to produce inhalable CBD powders with enhanced solubility and characterise their solid-state properties. CBD was spray freeze dried with mannitol or trehalose dihydrate with and without dipalmitoylphosphatidylcholine (DPPC). All four powders had acceptable yields at > 70 % with porous and spherical particles. The two crystalline mannitol powders contained less residual solvent than both amorphous trehalose ones. The addition of DPPC did not affect the crystallinity and residual solvent level of the powders. Instead, DPPC made the particles more porous, decreased the particle size from 19-23 µm to 11-13 µm, and increased CBD solubility from 0.36 µg/mL to over 2 µg/mL. The two DPPC powders were dispersed from a low resistance RS01 inhaler, showing acceptable aerosol performance with emitted fractions at 91-93 % and fine particle fractions < 5 µm at 34-43 %. These formulations can be used as a platform to deliver CBD and other cannabinoids by inhalation.

Quantitative summary on the human pharmacokinetic properties of cannabidiol to accelerate scientific clinical application of cannabis

Cannabidiol (CBD) is a non-psychoactive substance that exerts numerous pharmacological benefits, including anti-inflammatory and antioxidant properties. It has received attention as a useful substance for the treatment of intractable pain, seizures, and anxiety, and related clinical trials have continued. However, the CBD pharmacokinetic results between reports are highly variable, making it difficult to clearly identify the pharmacokinetic properties of CBD. The main purpose of this study was to identify CBD clinical pharmacokinetic properties through meta-analysis. In particular, we sought to derive valid, interpretable independent variables and interpret their pharmacokinetic parameter correlations in relation to the large inter-individual and inter-study variability in CBD pharmacokinetics. For this study, CBD-related clinical trial reports were extensively screened and intercomparisons were performed between internal data sets through systematic classification and extraction of pharmacokinetic parameter values. The candidate independent variables associated with interpretation of CBD pharmacokinetic diversity established and explored in this study were as follows: diet, tetrahydrocannabinol (THC) combination, sample matrix type, liver and renal function, exposure route, dosage form, CBD exposure dose, cannabis smoking frequency, multiple exposure. The results of this study showed that CBD pharmacokinetics were influenced (increased plasma exposure by approximately 2-5 times) by diet immediately before or during CBD exposure, and that THC was not expected to have an antagonistic effect on the CBD absorption. The influence of changes in liver function would be significant in CBD pharmacokinetic diversity. Due to decreased liver function, the plasma exposure of CBD increased 2.57-5.15 times compared to healthy adults, and the half-life and clearance showed a 2.58-fold increase and a 5.15-fold decrease, respectively. CBD can be rapidly absorbed into the body (time to reach maximum concentration within 3.18 h) by oral, transdermal, and inhalation exposures, and lipid emulsification and nanoformulation of CBD will greatly improve CBD bioavailability (up to approximately 2 times). The pharmacokinetics of CBD generally follow linear kinetic characteristics. The importance of this study is that it suggests key factors that should be considered in terms of pharmacokinetics in further clinical trials and formulations of CBD in the future.

Cannabidiol Bioavailability Is Nonmonotonic with a Long Terminal Elimination Half-Life: A Pharmacokinetic Modeling-Based Analysis

Background: Oral and inhalation-based cannabidiol (CBD) administration has been clinically evaluated for various therapeutic indications, alongside widespread off-label use. However, the long-term exposure kinetics and varied bioavailability have not been fully characterized. Methods: Human CBD plasma concentration-time profiles from six studies evaluating the oral administration of Epidiolex® and three studies evaluating inhalation-based delivery were obtained. A four-compartment pharmacokinetic (PK) model with Weibull-based oral absorption kinetics was employed to describe the long-term PKs of CBD. Furthermore, a Cedergreen-Ritz-Streibig model was applied to evaluate nonmonotonic oral bioavailability. Results: CBD was extensively distributed into tissue compartments with varied kinetics resulting in a long plasma terminal elimination half-life of >134 h in humans. For once-a-day oral dosing, the plasma trough concentrations require >70 days to reach a steady state. The oral bioavailability of CBD for different doses administered in fasted state follows a nonmonotonic pattern with an inverted U-shaped profile. Oral administration of CBD under fed state or subjects with hepatic impairment yields higher oral bioavailability with varied exposure. In contrast, inhalation-based delivery of CBD, while delivering a similar systemic delivered dose compared with oral dosing due to high device losses, bypasses first-pass metabolism and can be efficient. Conclusion: CBD PKs vary across different doses due to nonmonotonic oral bioavailability, and inhalation-based delivery could minimize such variability in humans. The delayed attainment of steady state and prolonged terminal half-life, resulting from differential but extensive tissue distribution, needs to be considered when dosing CBD in the long term. These fundamental findings are critical for establishing dose-exposure relationship for further clinical evaluation of novel CBD-based therapies.

Polycaprolactone microparticles for the subcutaneous administration of cannabidiol: in vitro and in vivo release

Cannabidiol (CBD) has become a highly attractive entity in therapeutics. However, its low aqueous solubility, instability and handling problems limit the development of effective CBD formulations. Subcutaneously administered CBD-loaded polycaprolactone microparticles (MP) represent an interesting strategy to overcome these challenges. This work focuses on evaluating the pharmacokinetics of CBD formulated in polymer microparticles for subcutaneous administration and characterising its release. The mean release time (MRLT) parameter is used to compare the release of CBD from two microparticle formulations in vitro and in a mouse model. After the administration of CBD in solution, a bicompartmental distribution is observed due to the extensive diffusion to the brain, being the brain/blood AUC ratio 1.29. The blood and brain mean residence time (MRT) are 0.507 ± 0.04 and 0.257 ± 0.0004 days, respectively. MP prepared with two drug/polymer ratios (15/150-MP and 30/150-MP) are designed, showing similar in vitro dissolution profiles (similarity factor (f2) is 63.21), without statistically significant differences between MRLTin vitro values (4.68 ± 0.63 and 4.32 ± 0.05 days). However, considerable differences in blood and brain profiles between both formulations are detected. The blood and brain MRT values of 15/150-MP are 6.44 ± 0.3 days and 6.15 ± 0.25 days, respectively, whereas significantly lower values 3.91 ± 0.29 days and 2.24 ± 0.64 days are obtained with 30/150-MP. The extended release of CBD during 10 days after a single subcutaneous administration is achieved.

Cannabinoid treatments in epilepsy and seizure disorders

Cannabis has been used to treat convulsions and other disorders since ancient times. In the last few decades, preclinical animal studies and clinical investigations have established the role of cannabidiol (CBD) in treating epilepsy and seizures and support potential therapeutic benefits for cannabinoids in other neurological and psychiatric disorders. Here, we comprehensively review the role of cannabinoids in epilepsy. We briefly review the diverse physiological processes mediating the central nervous system response to cannabinoids, including Δ9-tetrahydrocannabinol (Δ9-THC), cannabidiol, and terpenes. Next, we characterize the anti- and proconvulsive effects of cannabinoids from animal studies of acute seizures and chronic epileptogenesis. We then review the clinical literature on using cannabinoids to treat epilepsy, including anecdotal evidence and case studies as well as the more recent randomized controlled clinical trials that led to US Food and Drug Administration approval of CBD for some types of epilepsy. Overall, we seek to evaluate our current understanding of cannabinoids in epilepsy and focus future research on unanswered questions.

CBD and THC in Special Populations: Pharmacokinetics and Drug-Drug Interactions

Cannabinoid use has surged in the past decade, with a growing interest in expanding cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC) applications into special populations. Consequently, the increased use of CBD and THC raises the risk of drug-drug interactions (DDIs). Nevertheless, DDIs for cannabinoids, especially in special populations, remain inadequately investigated. While some clinical trials have explored DDIs between therapeutic drugs like antiepileptic drugs and CBD/THC, more potential interactions remain to be examined. This review summarizes the published studies on CBD and THC-drug interactions, outlines the mechanisms involved, discusses the physiological considerations in pharmacokinetics (PK) and DDI studies in special populations (including pregnant and lactating women, pediatrics, older adults, patients with hepatic or renal impairments, and others), and presents modeling approaches that can describe the DDIs associated with CBD and THC in special populations. The PK of CBD and THC in special populations remain poorly characterized, with limited studies investigating DDIs involving CBD/THC in these populations. Therefore, it is critical to evaluate potential DDIs between CBD/THC and medications that are commonly used in special populations. Modeling approaches can aid in understanding these interactions.

Strategies to Improve Cannabidiol Bioavailability and Drug Delivery

The poor physicochemical properties of cannabidiol (CBD) hamper its clinical development. The aim of this review was to examine the literature to identify novel oral products and delivery strategies for CBD, while assessing their clinical implications and translatability. Evaluation of the published literature revealed that oral CBD strategies are primarily focused on lipid-based and emulsion solutions or encapsulations, which improve the overall pharmacokinetics (PK) of CBD. Some emulsion formulations demonstrate more rapid systemic delivery. Variability in the PK effects of different oral CBD products is apparent across species. Several novel administration routes exist for CBD delivery that may offer promise for specific indications. For example, intranasal administration and inhalation allow quick delivery of CBD to the plasma and the brain, whereas transdermal and transmucosal administration routes deliver CBD systemically more slowly. There are limited but promising data on novel delivery routes such as intramuscular and subcutaneous. Very limited data show that CBD is generally well distributed across tissues and that some CBD products enable increased delivery of CBD to different brain regions. However, evidence is limited regarding whether changes in CBD PK profiles and tissue distribution equate to superior therapeutic efficacy across indications and whether specific CBD products might be suited to particular indications.

An Intravenous Pharmacokinetic Study of Cannabidiol Solutions in Piglets through the Application of a Validated Ultra-High-Pressure Liquid Chromatography Coupled to Tandem Mass Spectrometry Method for the Simultaneous Quantification of CBD and Its Carboxylated Metabolite in Plasma

Cannabidiol (CBD) has multiple therapeutic benefits that need to be maximized by optimizing its bioavailability. Numerous formulations are therefore being developed and their pharmacokinetics need to be studied, requiring analytical methods and data from intravenous administration. As CBD is susceptible to hepatic metabolism, the requirement of any method is to quantify metabolites such as 7-COOH-CBD. We demonstrated that CBD and 7-COOH-CBD could be simultaneously and correctly quantified in piglet plasma by using an UHPLC-MS/MS technique. The validated method allowed for an accurate bioanalysis of an intravenously injected solution consisting of CBD-HPβCD complexes. The experimental pharmacokinetic profile of CBD showed multi-exponential decay characterized by a fast apparent distribution half-life (0.25 h) and an elimination half-life of two hours. The profile of 7-COOH-CBD was not linked with the first-pass metabolism, since 80% of the maximum metabolite concentration was reached at the first sampling time point, without any decrease during the period of study. A two-compartment model was optimal to describe the experimental CBD profile. This model allowed us to calculate macro-micro constants and volumes of distribution (Vss = 3260.35 ± 2286.66 mL) and clearance (1514.5 ± 261.16 mL·h-1), showing that CBD is rapidly distributed to peripheral tissues once injected and slowly released into the bloodstream.

Cannabidiol - Help and hype in targeting mucosal diseases

Cannabidiol (CBD) is one of the most commonly utilised phytocannabinoids due to its non-psychoactive and multiple potential therapeutic properties and its non-selective pharmacology. Recent studies have demonstrated efficacy of CBD in some types of drug resistant epilepsies in combination with other therapies; comparative efficacy to other agents or placebo has been hoped for anxiety, chronic pain, and inflammatory disorders based on animal data. Although CBD products are generally treated as a restricted substance, these are being eased, partially in response to significant growth in CBD product usage and increased production but more due to emerging evidence about its safety and pharmacological properties. Currently, only one CBD product (Epidiolex®) has been approved by the Australian Therapeutic Goods Administration and US Food and Drug Administration. CBD has demonstrated promise in alleviating gut and lung diseases in vitro; however, its physicochemical properties pose a significant barrier to achieving pharmacological effects in in vivo and clinical trials. Improving CBD formulations and delivery methods using technologies including self-emulsifying emulsion, nano and micro particles could overcome these shortfalls and improve its efficacy. This review focuses on the therapeutic potential of CBD in gastrointestinal and lung diseases from the available in vitro, in vivo, and clinical research. We report on identified research gaps and obstacles in the development of CBD-based therapeutics, including novel delivery methods.

Inhalant Cannabidiol Inhibits Glioblastoma Progression Through Regulation of Tumor Microenvironment

Introduction: Glioblastoma (GBM) is the most common invasive brain tumor composed of diverse cell types with poor prognosis. The highly complex tumor microenvironment (TME) and its interaction with tumor cells play important roles in the development, progression, and durability of GBM. Angiogenic and immune factors are two major components of TME of GBM; their interplay is a major determinant of tumor vascularization, immune profile, as well as immune unresponsiveness of GBM. Given the ineffectiveness of current standard therapies (surgery, radiotherapy, and concomitant chemotherapy) in managing patients with GBM, it is necessary to develop new ways of treating these lethal brain tumors. Targeting TME, altering tumor ecosystem may be a viable therapeutic strategy with beneficial effects for patients in their fight against GBM. Materials and Methods: Given the potential therapeutic effects of cannabidiol (CBD) in a wide spectrum of diseases, including malignancies, we tested, for the first time, whether inhalant CBD can inhibit GBM tumor growth using a well-established orthotopic murine model. Optical imaging, histology, immunohistochemistry, and flow cytometry were employed to describe the outcomes such as tumor progression, cancer cell signaling pathways, and the TME. Results: Our findings showed that inhalation of CBD was able to not only limit the tumor growth but also to alter the dynamics of TME by repressing P-selectin, apelin, and interleukin (IL)-8, as well as blocking a key immune checkpoint-indoleamine 2,3-dioxygenase (IDO). In addition, CBD enhanced the cluster of differentiation (CD) 103 expression, indicating improved antigen presentation, promoted CD8 immune responses, and reduced innate Lymphoid Cells within the tumor. Conclusion: Overall, our novel findings support the possible therapeutic role of inhaled CBD as an effective, relatively safe, and easy to administer treatment adjunct for GBM with significant impacts on the cellular and molecular signaling of TME, warranting further research.

Cannabidiol for the Treatment of Brain Disorders: Therapeutic Potential and Routes of Administration

The use of cannabidiol (CBD) for treating brain disorders has gained increasing interest. While the mechanism of action of CBD in these conditions is still under investigation, CBD has been shown to affect numerous different drug targets in the brain that are involved in brain disorders. Here we review the preclinical and clinical evidence on the potential therapeutic use of CBD in treating various brain disorders. Moreover, we also examine various drug delivery approaches that have been applied to CBD. Due to the slow absorption and low bioavailability with the current oral CBD therapy, more efficient routes of administration to bypass hepatic metabolism, particularly pulmonary delivery, should be considered. Comparison of pharmacokinetic studies of different delivery routes highlight the advantages of intranasal and inhalation drug delivery over other routes of administration (oral, injection, sublingual, buccal, and transdermal) for treating brain disorders. These two routes of delivery, being non-invasive and able to achieve fast absorption and increase bioavailability, are attracting increasing interest for CBD applications, with more research and development expected in the near future.

Alleviating anxiety and taming trauma: Novel pharmacotherapeutics for anxiety disorders and posttraumatic stress disorder

Psychiatric disorders associated with psychological trauma, stress and anxiety are a highly prevalent and increasing cause of morbidity worldwide. Current therapeutic approaches, including medication, are effective in alleviating symptoms of anxiety disorders and posttraumatic stress disorder (PTSD), at least in some individuals, but have unwanted side-effects and do not resolve underlying pathophysiology. After a period of stagnation, there is renewed enthusiasm from public, academic and commercial parties in designing and developing drug treatments for these disorders. Here, we aim to provide a snapshot of the current state of this field that is written for neuropharmacologists, but also practicing clinicians and the interested lay-reader. After introducing currently available drug treatments, we summarize recent/ongoing clinical assessment of novel medicines for anxiety and PTSD, grouped according to primary neurochemical targets and their potential to produce acute and/or enduring therapeutic effects. The evaluation of putative treatments targeting monoamine (including psychedelics), GABA, glutamate, cannabinoid, cholinergic and neuropeptide systems, amongst others, are discussed. We emphasize the importance of designing and clinically assessing new medications based on a firm understanding of the underlying neurobiology stemming from the rapid advances being made in neuroscience. This includes harnessing neuroplasticity to bring about lasting beneficial changes in the brain rather than - as many current medications do - produce a transient attenuation of symptoms, as exemplified by combining psychotropic/cognitive enhancing drugs with psychotherapeutic approaches. We conclude by noting some of the other emerging trends in this promising new phase of drug development.

THC and CBD: Similarities and differences between siblings

Δ9-tetrahydrocannabinol (THC) and its sibling, cannabidiol (CBD), are produced by the same Cannabis plant and have similar chemical structures but differ dramatically in their mechanisms of action and effects on brain functions. Both THC and CBD exhibit promising therapeutic properties; however, impairments and increased incidence of mental health diseases are associated with acute and chronic THC use, respectively, and significant side effects are associated with chronic use of high-dose CBD. This review covers recent molecular and preclinical discoveries concerning the distinct mechanisms of action and bioactivities of THC and CBD and their impact on human behavior and diseases. These discoveries provide a foundation for the development of cannabinoid-based therapeutics for multiple devastating diseases and to assure their safe use in the growing legal market of Cannabis-based products.

Beyond CBD: Inhibitory effects of lesser studied phytocannabinoids on human voltage-gated sodium channels

Introduction: Cannabis contains cannabidiol (CBD), the main non-psychoactive phytocannabinoid, but also many other phytocannabinoids that have therapeutic potential in the treatment of epilepsy. Indeed, the phytocannabinoids cannabigerolic acid (CBGA), cannabidivarinic acid (CBDVA), cannabichromenic acid (CBCA) and cannabichromene (CBC) have recently been shown to have anti-convulsant effects in a mouse model of Dravet syndrome (DS), an intractable form of epilepsy. Recent studies demonstrate that CBD inhibits voltage-gated sodium channel function, however, whether these other anti-convulsant phytocannabinoids affect these classic epilepsy drug-targets is unknown. Voltage-gated sodium (Na_V) channels play a pivotal role in initiation and propagation of the neuronal action potential and Na_V1.1, Na_V1.2, Na_V1.6 and Na_V1.7 are associated with the intractable epilepsies and pain conditions. Methods: In this study, using automated-planar patch-clamp technology, we assessed the profile of the phytocannabinoids CBGA, CBDVA, cannabigerol (CBG), CBCA and CBC against these human voltage-gated sodium channels subtypes expressed in mammalian cells and compared the effects to CBD. Results: CBD and CBGA inhibited peak current amplitude in the low micromolar range in a concentration-dependent manner, while CBG, CBCA and CBC revealed only modest inhibition for this subset of sodium channels. CBDVA inhibited Na_V1.6 peak currents in the low micromolar range in a concentration-dependent fashion, while only exhibiting modest inhibitory effects on Na_V1.1, Na_V1.2, and Na_V1.7 channels. CBD and CBGA non-selectively inhibited all channel subtypes examined, whereas CBDVA was selective for Na_V1.6. In addition, to better understand the mechanism of this inhibition, we examined the biophysical properties of these channels in the presence of each cannabinoid. CBD reduced Na_V1.1 and Na_V1.7 channel availability by modulating the voltage-dependence of steady-state fast inactivation (SSFI, V_0.5 inact), and for Na_V1.7 channel conductance was reduced. CBGA also reduced Na_V1.1 and Na_V1.7 channel availability by shifting the voltage-dependence of activation (V_0.5 act) to a more depolarized potential, and for Na_V1.7 SSFI was shifted to a more hyperpolarized potential. CBDVA reduced channel availability by modifying conductance, SSFI and recovery from SSFI for all four channels, except for Na_V1.2, where V_0.5 inact was unaffected. Discussion: Collectively, these data advance our understanding of the molecular actions of lesser studied phytocannabinoids on voltage-gated sodium channel proteins.

Cys-loop receptors on cannabinoids: All high?

Endocannabinoids (eCBS) are endogenously derived lipid signaling molecules that serve as tissue hormones and interact with multiple targets, mostly within the endocannabinoid system (ECS). The ECS is a highly conserved regulatory system involved in homeostatic regulation, organ formation, and immunomodulation of chordates. The term “cannabinoid” evolved from the distinctive class of plant compounds found in Cannabis sativa, an ancient herb, due to their action on CB1 and CB2 receptors. CB1/2 receptors are the primary targets for eCBs, but their effects are not limited to the ECS. Due to the high interest and extensive research on the ECS, knowledge on its constituents and physiological role is substantial and still growing. Crosstalk and multiple targeting of molecules are common features of endogenous and plant compounds. Cannabimimetic molecules can be divided according to their origin, natural or synthetic, including phytocannabinoids (pCB’s) or synthetic cannabinoids (sCB’s). The endocannabinoid system (ECS) consists of receptors, transporters, enzymes, and signaling molecules. In this review, we focus on the effects of cannabinoids on Cys-loop receptors. Cys-loop receptors belong to the class of membrane-bound pentameric ligand gated ion channels, each family comprising multiple subunits. Mammalians possess GABA type A receptors (GABAAR), glycine receptors (GlyR), serotonin receptors type 3 (5-HT3R), and nicotinic acetylcholine receptors (nAChR). Several studies have shown different modulatory effects of CBs on multiple members of the Cys-loop receptor family. We highlight the existing knowledge, especially on subunits and protein domains with conserved binding sites for CBs and their possible pharmacological and physiological role in epilepsy and in chronic pain. We further discuss the potential for cannabinoids as first line treatments in epilepsy, chronic pain and other neuropsychiatric conditions, indicated by their polypharmacology and therapeutic profile.

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.

The safety and efficacy of low oral doses of cannabidiol: An evaluation of the evidence

Global interest in the non-intoxicating cannabis constituent, cannabidiol (CBD), is increasing with claims of therapeutic effects across a diversity of health conditions. At present, there is sufficient clinical trial evidence to support the use of high oral doses of CBD (e.g., 10-50 mg/kg) in treating intractable childhood epilepsies. However, a question remains as to whether "low-dose" CBD products confer any therapeutic benefits. This is an important question to answer, as low-dose CBD products are widely available in many countries, often as nutraceutical formulations. The present review therefore evaluated the efficacy and safety of low oral doses of CBD. The review includes interventional studies that measured the clinical efficacy in any health condition and/or safety and tolerability of oral CBD dosed at less than or equal to 400 mg per day in adult populations (i.e., ≥18 years of age). Studies were excluded if the product administered had a Δ⁹ -tetrahydrocannabinol content greater than 2.0%. Therapeutic benefits of CBD became more clearly evident at doses greater than or equal to 300 mg. Increased dosing from 60 to 400 mg/day did not appear to be associated with an increased frequency of adverse effects. At doses of 300-400 mg, there is evidence of efficacy with respect to reduced anxiety, as well as anti-addiction effects in drug-dependent individuals. More marginal and less consistent therapeutic effects on insomnia, neurological disorders, and chronic pain were also apparent. Larger more robust clinical trials are needed to confirm the therapeutic potential of lower (i.e., <300 mg/day) oral doses of CBD.

Oral inhalation of cannabidiol delivered from a metered dose inhaler to alleviate cytokine production induced by SARS-CoV-2 and pollutants

Cannabidiol (CBD) was formulated as a metered dose inhaler (CBD-MDI) and evaluated in vitro for its efficacy as an inhaled dosage form against inflammation caused by the SARS-CoV-2 virus, lipopolysaccharide (LPS) from Escherichia coli, silica particles, nicotine, and coal tar. A CBD-MDI formulation was prepared with 50 mg of CBD in 10 mL for a CBD dose of 250 μg/puff. The formulation ingredients included CBD, absolute ethanol as a cosolvent, and HFA-134a as the propellant. High aerosol performance of CBD-MDI was obtained with mass median aerodynamic diameter of 1.25 ± 0.01 μm, geometric standard deviation of 1.75 ± 0.00, emitted dose of 244.7 ± 2.1 μg, and fine particle dose of 122.0 ± 1.6 μg. The cytotoxicity and anti-inflammatory effectiveness of CBD-MDI were performed in alveolar macrophage (NR8383) and co-culture of alveolar macrophage (NR8383) and human lung adenocarcinoma (A549) cell line. CBD delivered from an MDI was safe on respiratory cells and did not trigger an immune response in alveolar macrophages. CBD-MDI effectively reduced the generation of cytokines in immune cells treated with viral antigen S-RBD, bacterial antigen LPS, silica particles, and coal tar. The efficacy of CBD-MDI was comparable to budesonide. Furthermore, the findings demonstrated that the use of CBD-MDI was more effective in treatment rather than prevention when inflammation was induced by either a viral or bacterial stimulant.

Recent advances in drug delivery to the central nervous system by inhalation

INTRODUCTION

Drugs need to enter the systemic circulation efficiently before they can cross the blood-brain barrier and reach the central nervous system. Although the respiratory tract is not a common route of administration for delivering drugs to the central nervous system, it has attracted increasing interest in recent years for this purpose.

AREAS COVERED

In this article, we compare pulmonary delivery to three other common routes (parenteral, oral, and intranasal) for delivering drugs to the central nervous system, followed by summarising the devices used to aerosolise neurological drugs. Recent studies delivering drugs for different neurological disorders via inhalation are then discussed to illustrate the strengths of pulmonary delivery.

EXPERT OPINION

Recent studies provide strong evidence and rationale to support inhaling neurological drugs. Since inhalation can achieve improved pharmacokinetics and rapid onset of action for multiple drugs, it is a non-invasive and efficient method to deliver drugs to the central nervous system. Future research should focus on delivering other small and macro-molecules via the lungs for different neurological conditions.

Biophysical Studies and In Vitro Effects of Tumor Cell Lines of Cannabidiol and Its Cyclodextrin Inclusion Complexes

Phytocannabinoids possess anticancer properties, as established in vitro and in vivo. However, they are characterized by high lipophilicity. To improve the properties of cannabidiol (CBD), such as solubility, stability, and bioavailability, CBD inclusion complexes with cyclodextrins (CDs) might be employed, offering targeted, faster, and prolonged CBD release. The aim of the present study is to investigate the in vitro effects of CBD and its inclusion complexes in randomly methylated β-CD (RM-β-CD) and 2-hyroxypropyl-β-CD (HP-β-CD). The enhanced solubility of CBD upon complexation with CDs was examined by phase solubility study, and the structure of the inclusion complexes of CBD in 2,6-di-O-methyl-β-CD (DM-β-CD) and 2,3,6-tri-O-methyl-β-CD (TM-β-CD) was determined by X-ray crystallography. The structural investigation was complemented by molecular dynamics simulations. The cytotoxicity of CBD and its complexes with RM-β-CD and HP-β-CD was tested on two cell lines, the A172 glioblastoma and TE671 rhabdomyosarcoma cell lines. Methylated β-CDs exhibited the best inclusion ability for CBD. A dose-dependent effect of CBD on both cancer cell lines and improved efficacy of the CBD–CDs complexes were verified. Thus, cannabinoids may be considered in future clinical trials beyond their palliative use as possible inhibitors of cancer growth.

Development of Stable Nano-Sized Transfersomes as a Rectal Colloid for Enhanced Delivery of Cannabidiol

Current cannabidiol (CBD) formulations are challenged with unpredictable release and absorption. Rational design of a rectal colloid delivery system can provide a practical alternative. In this study the inherent physiochemical properties of transferosomes were harnessed for the development of a nano-sized transfersomes to yield more stable release, absorption, and bioavailability of CBD as a rectal colloid. Transfersomes composed of soya lecithin, cholesterol, and polysorbate 80 were synthesized via thin film evaporation and characterized for size, entrapment efficiency (%), morphology, CBD release, ex vivo permeation, and physicochemical stability. The optimized formulation for rectal delivery entrapped up to 80.0 ± 0.077% of CBD with a hydrodynamic particle size of 130 nm, a PDI value of 0.285, and zeta potential of −15.97 mV. The morphological investigation via SEM and TEM revealed that the transfersomes were spherical and unilamellar vesicles coinciding with the enhanced ex vivo permeation across the excised rat colorectal membrane. Furthermore, transfersomes improved the stability of the encapsulated CBD for up to 6 months at room temperature and showed significant promise that the transfersomes promoted rectal tissue permeation with superior stability and afforded tunable release kinetics of CBD as a botanical therapeutic with inherent poor bioavailability.