In vitro percutaneous absorption studies of cannabidiol using human skin: Exploring the effect of drug concentration, chemical enhancers, and essential oils

Ultrathin silk nanofiber-carbon nanotube skin tattoos for wirelessly triggered and temperature feedbacked transdermal drug delivery

Transdermal drug delivery has emerged as an alternative to conventional drug delivery systems as it enables painless and convenient drug administration. However, next-generation healthcare systems need to facilitate "on-demand" delivery operations and should be highly efficient to penetrate the physiological barriers in the skin. Here, we report an ultrathin dye-loaded epidermal tattoo (UDET) that allows wirelessly stimulated drug delivery with high efficiency. The UDET consists of an electrospun dye-loaded silk nanofiber mat and a covered carbon nanotube (CNT) layer. UDETs are conformally tattooed on pigskins and show stable operation under mechanical deformation. Biological fluorescence dyes such as vitamin B12, riboflavin, rhodamine B, and sodium fluorescein are applied as model drugs. Illuminating the UDET by a low-power light-emitting diode (< 34.5 mW/cm2) triggers transdermal drug delivery due to heat generation. The CNTs convert the absorbed light into heat, and then the dyes loaded on silk can be diffused through the epidermis. The CNT layer is electrically conductive and can detect the temperature by reading the resistance change (0.1917 Ω/°C). This indicates that the UDET can be used simultaneously to read temperature and deliver the loaded dye molecules, making it a promising on-demand drug delivery strategy for future medicine technology.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13534-024-00363-6.

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.

Development and Characterization of a Microemulsion Containing a Cannabidiol Oil and a Hydrophilic Extract from Sambucus ebulus for Topical Administration

Cannabidiol (CBD) is a safe and non-psychotropic phytocannabinoid with a wide range of potential therapeutic anti-inflamatory and antioxidant activities. Due to its lipophilicity, it is normally available dissolved in oily phases. The main aim of this work was to develop and characterize a new formulation of a microemulsion with potential anti-inflammatory and antioxidant activity for the topical treatment of inflammatory skin disorders. The microemulsion system was composed of a 20% CBD oil, which served as the hydrophobic phase; Labrasol/Plurol Oleique (1:1), which served as surfactant and cosurfactant (S/CoS), respectively; and an aqueous vegetal extract obtained from Sambucus ebulus L. (S. ebulus) ripe fruits, which has potential anti-oxidant and anti-inflammatory activity and which served as the aqueous phase. A pseudo-ternary phase diagram was generated, leading to the selection of an optimal proportion of 62% (S/CoS), 27% CBD oil and 11% water and, after its reproducibility was tested, the aqueous phases were replaced by the vegetal hydrophilic extract. The defined systems were characterized in terms of conductivity, droplet size (by laser scattering), compatibility of components (by differential scanning calorimetry) and rheological properties (using a rotational rheometer). The designed microemulsion showed good stability and slight pseudo-plastic behavior. The release properties of CBD from the oil phase and caffeic acid from the aqueous phase of the microemulsion were studied via in vitro diffusion experiments using flow-through diffusion cells and were compared to those of a CBD oil and a microemulsion containing only CBD as an active substance. It was found that the inclusion of the original oil in microemulsions did not result in a significant modification of the release of CBD, suggesting the possibility of including hydrophilic active compounds in the formulation and establishing an interesting strategy for the development of future formulations.

Nanosuspension-Loaded Dissolving Microneedle Patches for Enhanced Transdermal Delivery of a Highly Lipophilic Cannabidiol

Purpose

Transdermal Drug Delivery System (TDDS) offers a promising alternative for delivering poorly soluble drugs, challenged by the stratum corneum's barrier effect, which restricts the pool of drug candidates suitable for TDDS. This study aims to establish a delivery platform specifically for highly lipophilic drugs requiring high doses (log P > 5, dose > 10 mg/kg/d), to improve their intradermal delivery and enhance solubility.

Methods

Cannabidiol (CBD, log P = 5.91) served as the model drug. A CBD nanosuspension (CBD-NS) was prepared using a bottom-up method. The particle size, polydispersity index (PDI), zeta potential, and concentration of the CBD-NS were characterized. Subsequently, CBD-NS was incorporated into dissolving microneedles (DMNs) through a one-step manufacturing process. The intradermal dissolution abilities, physicochemical properties, mechanical strength, insertion depth, and release behavior of the DMNs were evaluated. Sprague-Dawley (SD) rats were utilized to assess the efficacy of the DMN patch in treating knee synovitis and to analyze its skin permeation kinetics and pharmacokinetic performance.

Results

The CBD-NS, stabilized with Tween 80, exhibited a particle size of 166.83 ± 3.33 nm, a PDI of 0.21 ± 0.07, and a concentration of 46.11 ± 0.52 mg/mL. The DMN loaded with CBD-NS demonstrated favorable intradermal dissolution and mechanical properties. It effectively increased the delivery of CBD into the skin, extended the action's duration in vivo, and enhanced bioavailability. CBD-NS DMN exhibited superior therapeutic efficacy and safety in a rat model of knee synovitis, significantly inhibiting TNF-α and IL-1β compared with the methotrexate subcutaneous injection method.

Conclusion

NS technology effectively enhances the solubility of the poorly soluble drug CBD, while DMN facilitates penetration, extends the duration of action in vivo, and improves bioavailability. Furthermore, CBD has shown promising therapeutic outcomes in treating knee synovitis. This innovative drug delivery system is expected to offer a more efficient solution for the administration of highly lipophilic drugs akin to CBD, thereby facilitating high-dose administration.

Comparative evaluation of physical and chemical enhancement techniques for transdermal delivery of linagliptin

Linagliptin is a dipeptidyl peptidase-4 inhibitor used for the management of type-2 diabetes. US FDA-approved products are available exclusively as oral tablets. The inherent drawbacks of the oral administration route necessitate exploring delivery strategies via other routes. In this study, we investigated the feasibility of transdermal administration of linagliptin through various approaches. We compared chemical penetration enhancers (oleic acid, oleyl alcohol, and isopropyl myristate) and physical enhancement techniques (iontophoresis, sonophoresis, microneedles, laser, and microdermabrasion) to understand their potential to improve transdermal delivery of linagliptin. To our knowledge, this is the first reported comparison of chemical and physical enhancement techniques for the transdermal delivery of a moderately lipophilic molecule. All physical enhancement techniques caused a significant reduction in the transepithelial electrical resistance of the skin samples. Disruption of the skin's structure post-treatment with physical enhancement techniques was further confirmed using characterization techniques such as dye binding, histology, and confocal microscopy. In vitro permeation testing (IVPT) demonstrated that the passive delivery of linagliptin across the skin was < 5 µg/sq.cm. Two penetration enhancers - oleic acid (93.39 ± 8.34 µg/sq.cm.) and oleyl alcohol (424.73 ± 42.86 µg/sq.cm.), and three physical techniques - iontophoresis (53.05 ± 0.79 µg/sq.cm.), sonophoresis (141.13 ± 34.22 µg/sq.cm.), and laser (555.11 ± 78.97 µg/sq.cm.) exceeded the desired target delivery for therapeutic effect. This study established that linagliptin is an excellent candidate for transdermal delivery and thoroughly compared chemical penetration and physical transdermal delivery strategies.

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.

Cutaneous Delivery and Biodistribution of Cannabidiol in Human Skin after Topical Application of Colloidal Formulations

The objective of this study was to investigate the cutaneous delivery of cannabidiol (CBD) from aqueous formulations developed for the targeted local treatment of dermatological conditions. CBD was formulated using a proprietary colloidal drug delivery system (VESIsorb®) into an aqueous colloidal solution at 2% (ACS 2%) and two colloidal gels (CG 1% and CG 2%, which contained 1% and 2% CBD, respectively). Two basic formulations containing CBD (5% in propylene glycol (PG 5%) and a 6.6% oil solution (OS 6.6%)) and two marketed CBD products (RP1 and RP2, containing 1% CBD) were used as comparators. Cutaneous delivery and cutaneous biodistribution experiments were performed using human abdominal skin (500-700 µm) under infinite- and finite-dose conditions with 0.5% Tween 80 in the PBS receiver phase. The quantification of CBD in the skin samples was performed using a validated UHPLC-MS/MS method and an internal standard (CBD-d3). The cutaneous deposition of CBD under finite-dose conditions demonstrated the superiority of CG 1%, CG 2%, and ACS 2% over the marketed products; CG 1% had the highest delivery efficiency (5.25%). Cutaneous biodistribution studies showed the superiority of the colloidal systems in delivering CBD to the viable epidermis, and the upper and lower papillary dermis, which are the target sites for the treatment of several dermatological conditions.

Development of an UHPLC-MS/MS method to determine cutaneous biodistribution of cannabidiol after topical application of cannabidiol gel assisted by iontophoresis

Cannabidiol has potential for use in skin disease therapy, so it is important to know the cutaneous biodistribution of cannabidiol after topical application of cannabidiol formulations. However, currently existing quantification methods for the investigation of cannabidiol skin distribution are not optimal. This study aimed to establish a method for the determination of cannabidiol in skin samples by UHPLC-MS/MS. A BEH C18 (50.0 × 2.1 mm, 2.5 μm) column was used; the mobile phase consisted of acetonitrile-0.1% formic acid (70:30, v/v), the flow rate was 0.2 μl·min-1 and the column temperature was 30°C. Positive-ion mode with multiple reaction monitoring detection was used to quantify cannabidiol (m/z 315.1 → 193.1) while diphenhydramine (m/z 256.3 → 167.08) served as the internal standard. Good linearity was shown in the range of 1-200 ng·ml-1 for cannabidiol with correlation coefficients of >0.999. The LLOQ was 1 ng·ml-1 . The intra-day and inter-day RSDs of cannabidiol were all <2%. A cryo-sectioning technique combined with the UHPLC-MS/MS method was used to successfully determine cannabidiol levels in a series of very thin skin layers.

Topical cannabidiol is well tolerated in individuals with a history of elite physical performance and chronic lower extremity pain

INTRODUCTION

Cannabidiol (CBD) is a potential therapeutic for pain management. Yet, there exists a dearth of studies of its tolerability and efficacy, especially in special populations. Former elite athletes are a special population both susceptible to chronic pain and also highly trained and attuned to assess medication tolerability concerns. The purpose of the present open-label pilot study was to assess the tolerability of CBD in this population.

MATERIALS AND METHODS

Retrospective analysis was conducted in deidentified data from 20 individuals who were all previously professional athletes in US/American football, track and field, or basketball, with careers ranging from 4 to 10 years. Participants received topical CBD (10 mg twice daily by controlled dispenser) for chronic pain resulting from acute lower extremity injuries. Assessments of tolerability and secondary analyses of pain, pain-related disability, and activities of daily living were collected by self-report over the 6-week study period. Data were analyzed by descriptive statistics, pairwise t-test, and linear regression.

RESULTS

Seventy percent of participants completed the study. Of the individuals who completed the study, 50% reported minor adverse effects, none of which required medical attention, and 50% did not report any adverse effects. The mostly commonly reported effects were skin dryness (43% of study completers) and skin rash (21% of study completers), which rapidly resolved. There was a significant improvement in self-reported pain levels (intake mean 3.5 ± 0.29; exit mean 1.7 ± 0.23; P < 0.001) and pain-related disability, including family and home responsibilities, life support activities, occupational activities, recreational activities, self-care, sexual function, and social activities (all P < 0.001).

DISCUSSION

To the best of our knowledge, this is the first study to assess CBD treatment in elite athletes, who are disproportionally susceptible to disabling injuries. Topical administration of CBD was tolerated well by this population and resulted in only minor adverse effects. As elite athletes are trained and attuned to assess their own bodies due to their professional lives, this population is likely to detect tolerability concerns. However, this study was limited to a convenience sample and self-reported data. These pilot findings warrant further study of topical CBD in randomized and controlled studies of elite athletes.

Oxymatrine-fatty acid deep eutectic solvents as novel penetration enhancers for transdermal drug delivery: formation mechanism and enhancing effect

Transdermal delivery of drugs is commonly limited by low skin permeability. The aim of the study was to synthesize deep eutectic solvents (DESs) based on oxymatrine (OMT) and fatty acids with various alkyl chain lengths (LCFAs) as novel vehicles, to solubilize the water-insoluble drug and enhance percutaneous penetration. Quercetin (QUE) was selected as a model drug. Combining differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and molecular simulations demonstrated that the formation of DESs was mediated by charge-assisted hydrogen bonding. Physicochemical properties including stability, viscosity, and solubilization capacity were also studied. Subsequently, the effect of three stable DESs on drug release and skin permeability was evaluated. The results showed that QUE was solubilized well and presented a different sustained release behavior in DESs. Meanwhile, DESs enhanced the skin permeation of OMT and QUE, which was influenced by alkyl chain lengths of LCFAs, whereas DES consisting of lauric acid (LA) exhibited the highest enhancing effect. FTIR, DSC, and molecular docking further demonstrated consistency between micro molecular mechanism and macro penetration behavior. Additionally, HaCaT cells treated with DESs showed high cell viability, suggesting their good skin safety. Taken together, OMT-LCFA DESs would be a promising penetration enhancer for transdermal drug delivery, which also provides guidance for the design of new DESs.

Cannabidiol-Loaded Nanostructured Lipid Carriers (NLCs) for Dermal Delivery: Enhancement of Photostability, Cell Viability, and Anti-Inflammatory Activity

The aim of this study was to encapsulate cannabidiol (CBD) extract in nanostructured lipid carriers (NLCs) to improve the chemical stability and anti-inflammatory activity of CBD for dermal delivery. CBD-loaded NLCs (CBD-NLCs) were prepared using cetyl palmitate (CP) as a solid lipid and stabilized with Tego^® Care 450 (TG450) or poloxamer 188 (P188) by high-pressure homogenization (HPH). The CBD extract was loaded at 1% w/w. Three different oils were employed to produce CBD-NLCs, including Transcutol^® P, medium-chain triglycerides (MCT), and oleic acid (OA). CBD-NLCs were successfully prepared with an entrapment efficiency (E.E.) of 100%. All formulations showed particle sizes between 160 and 200 nm with PDIs less than 0.10. The type of surfactant and oil used affected the particle sizes, zeta potential, and crystallinity of the CBD-NLCs. CBD-NLCs stabilized with TG450 showed higher crystallinity after production and storage at 30 °C for 30 days as compared to those with P188. Encapsulation of the CBD extract in NLCs enhanced its chemical stability after exposure to simulated sunlight (1000 kJ/m²) compared to that of the CBD extract in ethanolic solution. The CBD-NLCs prepared from MCT and OA showed slower CBD release compared with that from Transcutol^® P, and the kinetic data for release of CBD from CBD-NLCs followed Higuchi's release model with a high coefficient of determination (>0.95). The extent of CBD permeation through Strat-M^® depended on the oil type. The cytotoxicity of the CBD extract on HaCaT and HDF cells was reduced by encapsulation in the NLCs. The anti-inflammatory activity of the CBD extract in RAW264.7 cell macrophages was enhanced by encapsulation in CBD-NLCs prepared from MCT and OA.

Development and Evaluation of a Topical Foam Formulation for Decontamination of Warfare Agents

Lewisite is a highly toxic and potent chemical warfare vesicating agent capable of causing pain, inflammation, and blistering. Therapeutic strategies that safely and effectively attenuate this damage are important. Early and thorough decontamination of these agents from skin is required to prevent their percutaneous absorption. In our studies, we used phenylarsine oxide (PAO), a surrogate for arsenicals, to simulate lewisite exposure. Various parameters such as determination of extraction solvents, skin extraction efficiency, donor volume, and donor concentration were optimized for decontamination of PAO. We aimed to develop a novel, easy to apply foam formulation that can decontaminate arsenicals. We screened various foaming agents, vehicles, and chemical enhancers for the development of foam. Lead formulation foam F30 was further characterized for foam density, foam expansion, foam liquid stability, foam volume stability, and foam gas fraction. The amount of PAO delivered into human skin in 30 min of exposure was 228.57 ± 28.44 μg/sq·cm. The amount of PAO remaining in human skin after decontamination with blank foam F30 was 50.09 ± 9.71, demonstrating an overall percentage decontamination efficiency of over 75%. Furthermore, the decontamination efficacy of F30 was also tested in the porcine skin model and results indicated an even higher decontamination efficacy. These studies demonstrated that the developed foam formulation can be used for effective decontamination of chemical warfare agents.

Fabrication of Polymeric Microneedles using Novel Vacuum Compression Molding Technique for Transdermal Drug Delivery

PURPOSE

To demonstrate the feasibility of vacuum compression molding as a novel technique for fabricating polymeric poly (D, L-lactic-co-glycolic acid) microneedles.

METHODS

First, polydimethylsiloxane molds were prepared using metal microneedle templates and fixed in the MeltPrep® Vacuum Compression Molding tool. Poly (D, L-lactic-co-glycolic acid) (EXPANSORB® DLG 50-5A) was added, enclosed, and heated at 130°C for 15 min under a vacuum of -15 psi, cooled with compressed air for 15 min, followed by freezing at -20°C for 30 min, and stored in a desiccator. The microneedles and microchannels were characterized by a variety of imaging techniques. In vitro permeation of model drug lidocaine as base and hydrochloride salt was demonstrated across intact and microporated dermatomed human skin.

RESULTS

Fabricated PLGA microneedles were pyramid-shaped, sharp, uniform, and mechanically robust. Scanning electron microscopy, skin integrity, dye-binding, histology, and confocal laser microscopy studies confirmed the microchannel formation. The receptor delivery of lidocaine salt increased significantly in microporated (270.57 ± 3.73 μg/cm²) skin as compared to intact skin (142.19 ± 13.70 μg/cm²) at 24 h. The receptor delivery of lidocaine base from microporated skin was significantly higher (312.37 ± 10.57 μg/cm²) than intact skin (169.68 ± 24.09 μg/cm²) up to 8 h. Lag time decreased significantly for the base (2.24 ± 0.17 h to 0.64 ± 0.05 h) and salt (4.76 ± 0.31 h to 1.47 ± 0.21 h) after microporation.

CONCLUSION

Vacuum compression molding was demonstrated as a novel technique to fabricate uniform, solvent-free, strong polymer microneedles in a short time.

Design of Liposomal Lidocaine/Cannabidiol Fixed Combinations for Local Neuropathic Pain Treatment

The administration of drug fixed combinations by nanocarriers is a new attractive approach since it can allow improvements in both the skin penetration of cargo compounds and their synergistic effects. The cutaneous administration of lidocaine (LD) and cannabidiol (CBD) combination can be useful for the local treatment of neuropathic pain. In fact, these drugs might exert a complementary effect on pain acting on sodium and calcium channels. In this study, the feasibility to deliver this combination in the deeper layers of the skin using deformable liposomes was studied. Based on a study of the drug affinity for lipid components performed by DSC, CBD was loaded in the lipid bilayer for limiting the leakage, while LD was loaded in the inner core by a pH gradient method (G-liposomes) or after previous encapsulation in micelle (DiMiL). The effect of the presence of Tween 80 in the liposome membrane was also evaluated. DiMiL increased both the skin permeation and the retention in the dermis of CBD and LD with respect to G-liposomes (R_24dermis: 11.52 ± 2.4 against 4.51 ± 0.8 µg/cm² for CBD; 19.6 ± 2.9 against 3.2 ± 0.1 µg/cm² for LD). Moreover, both DiMiL and G-liposomes were more efficient than control formulations carrying free drugs in improving drug skin permeation. Interestingly, in the presence of a drug exerting a fluidizing effect such as CBD, the removal of Tween 80 from the composition led to an improved control of drug release and a higher extent of drug retention in the dermis layer.

In Vitro Release, Mucosal Permeation and Deposition of Cannabidiol from Liquisolid Systems: The Influence of Liquid Vehicles

This work investigated the influence of liquid vehicles on the release, mucosal permeation and deposition of cannabidiol (CBD) from liquisolid systems. Various vehicles, including EtOH, nonvolatile low- and semi-polar solvents, and liquid surfactants, were investigated. The CBD solution was converted into free-flowing powder using carrier (microcrystalline cellulose) and coating materials (colloidal silica). A physical mixture of the CBD and carrier–coating materials was prepared as a control. The non-crystalline state of CBD in the liquisolid systems was confirmed using XRD, FTIR and SEM studies. The CBD liquisolid powder prepared with volatile and nonvolatile solvents had a better CBD release performance than the CBD formed as the surfactant-based and control powders. The liquisolid systems provided the CBD permeation flux through porcine esophageal mucosa ranging from 0.68 ± 0.11 to 13.68 ± 0.74 µg·cm⁻²·h⁻¹, with the CBD deposition levels of 0.74 ± 0.04 to 2.62 ± 0.30 μg/mg for the dry mucosa. Diethylene glycol monoethyl ether showed significant CBD permeation enhancement (2.1 folds) without an increase in mucosal deposition, while the surfactants retarded the permeation (6.7–9.0 folds) and deposition (1.5–3.2 folds) significantly. In conclusion, besides the drug release, liquid vehicles significantly influence mucosal permeation and deposition, either enhanced or suppressed, in liquisolid systems. Special attention must be paid to the selection and screening of suitable liquid vehicles for liquisolid systems designed for transmucosal applications.

Enhancement of transdermal permeation of cannabinoids and their pharmacodynamic evaluation in rats

The objective of the present study was to enhance the transdermal permeation of cannabinoids: cannabidiol (CBD), cannabigerol (CBG) and tetrahydrocannabivarin (THCV) using chemical permeation enhancer approach and evaluate them for their anti-inflammatory effect in vivo in a paw edema model in rats. Cannabinoids gel formulations were developed using FDA approved inactive ingredients: lactic acid (LA), polyethylene glycol-400 (PEG-400), N-methyl-2 pyrrolidone (NMP), dimethyl sulfoxide (DMSO). In vitro skin permeation testing (IVPT) showed flux of ∼ 13.25 μg/cm²/h for CBD, ∼9.38 μg/cm²/h for CBG and ∼ 51.74 μg/cm²/h for THCV. Additionally, IVPT study showed cumulative drug permeation of 610.96 ± 88.92 μg/cm², 432.09 ± 35.59 μg/cm² and 2384.44 ± 42.22 μg/cm² from CBD, CBG and THCV gel formulations respectively. Further, effect of excipients on cannabinoid permeation showed that, formulation containing lactic acid, NMP and DMSO showed significantly (p < 0.0001) enhanced flux of cannabinoids as compared to formulation without LA, NMP and DMSO. In vivo studies showed that paw edema was significantly (p < 0.0001) reduced in the groups containing CBD, CBG, THCV as compared to control and placebo formulation. In conclusion, flux of CBD, CBG and THCV was significantly enhanced using chemical permeation enhancers approach which helped in reducing rat paw edema.

Mucosal Delivery of Cannabidiol: Influence of Vehicles and Enhancers

In this study, the mucosal permeation and deposition of cannabidiol (CBD) with neat and binary vehicles were investigated. Permeation experiments were performed using static diffusion cells coupled with fresh porcine esophageal mucosa. The CBD-vehicle solutions were applied at a fixed dose (~5 mg/cm²), and the corresponding permeation parameters were calculated. In neat vehicles, the permeation flux (J_ss) ranged from 0.89 ± 0.15 to 179.81 ± 23.46 µg·cm^-2·h^-1, while the CBD deposition ranged from 11.5 ± 1.8 to 538.3 ± 105.3 μg·cm^-2. Propylene glycol (PG) and diethylene glycol monoethyl ether (DEGEE) yielded the highest permeability (P_s) and CBD deposition, while medium-chain triglycerides (MCT) yielded the lowest P_s and deposition. This was due to the difference in apparent partition coefficient (K), which is related to the solubility of CBD in the vehicle. The PG:DEGEE binary vehicle boosted J_ss (1.5-1.6 fold) and deposition (2.0-2.7 folds) significantly, compared to neat DEGEE. The combination of DEGEE with MCT dramatically enhanced J_ss (11-44 fold) and deposition (1.6-4.7 fold). The addition of lipophilic enhancers, laurocapram, and oleic acid, to PG:DEGEE and DEGEE:MCT vehicles significantly reduced J_ss (0.3-0.7 fold) and deposition (0.4-0.8 fold) while nerolidol had no effect. These permeation reductions were found to be related to modification of the K and/or diffusivity values. This study provides useful basic information for the development of CBD formulations intended for transmucosal delivery.