In recent years, the interest in cannabidiol (CBD) has increased because of the lack of psychoactive properties. However, CBD has low solubility and bioavailability, variable pharmacokinetics profiles, poor stability, and a pronounced presystemic metabolism. CBD nanoformulations include nanosuspensions, polymeric micelles and nanoparticles, hybrid nanoparticles jelled in cross-linked chitosan, and numerous nanosized lipid formulations, including nanostructured lipid carriers, vesicles, SNEEDS, nanoemulsions, and microemulsions. Nanoformulations have resulted in high CBD solubility, encapsulation efficiency, and stability, and sustained CBD release. Some studies assessed the increased C_max and AUC and decreased T_max. A rational evaluation of the studies reported in this review evidences how some of them are very preliminary and should be completed before performing clinical trials. Almost all the developed nanoparticles have simple architectures, are well-known and safe nanocarriers, or are even simple nanosuspensions. In addition, the conventional routes of administration are generally investigated. As a consequence, many of these studies are almost ready for forthcoming clinical translations. Some of the developed nanosystems are very promising for a plethora of therapeutic opportunities because of the versatility in terms of the release, the crossing of physiological barriers, and the number of possible routes of administration.

Oleanolic acid (OA) is the main triterpenic acid of olive leaves known for numerous pharmacological properties, including antioxidant activity. However, it is poorly soluble in water and consequently with low bioavailability, which limits its pharmacological application. Microemulsions (MEs) are dispersed systems consisting of two immiscible phases that promote rapid solubilization and absorption in the gastrointestinal tract. To improve both solubility and intestinal permeability of this molecule, OA has been formulated in two different microemulsions (ME-1 and ME-2). A solubility screening was carried out to select the ME components, and pseudoternary phase diagrams were constructed to evaluate the region of existence and select the appropriate amount of the constituents. ME-1 was prepared using Capmul PG-8/NF as the oily phase, and Transcutol and Tween 20 (7:3) as surfactants, while ME-2 contained Nigella oil and Isopropil myristate as the oily phase, and Transcutol HP and Cremophor EL (2:1) as surfactants. The OA solubility was increased by 1000-fold and 3000-fold in ME-1-OA and ME-2-OA, respectively. The MEs’ droplet size and the PdI were evaluated, and the stability was assessed for 8 weeks by monitoring chemical and physical parameters. The parallel artificial membrane permeability assay (PAMPA) also demonstrated an enhanced intestinal permeability of both OA formulations compared with free OA. The potential ability of both MEs to enhance the bioactivity of OA against LPS-induced oxidative stress in RAW 264.7 murine macrophages was also investigated. Overall, this study suggests that both MEs promote a bio-enhancement of the protective action of OA against the LPS-induced pro-oxidant stress in macrophages. Overall, this study suggests that MEs could be an interesting formulation to improve OA oral bioavailability with potential clinical applications.

Background: Cannabidiol (CBD) is a highly lipophilic compound with potential therapeutic applications in neurological disorders. However, its poor aqueous solubility and bioavailability, coupled with instability in physiological conditions, significantly limit its clinical use. Objectives: This study aimed to develop and characterize nanovesicles incorporating Tween 20 to enhance CBD encapsulation, stability, and the performance across the blood–brain barrier (BBB). Methods: Nanovesicles were prepared via thin-film hydration followed by sonication and optimized for size, polydispersity index, and zeta potential. Stability studies were conducted under physiological conditions and during storage at 4 °C. In vitro release studies employed the dialysis bag method, while permeability across the BBB was assessed using PAMPA-BBB and the hCMEC/D3-BBB cell line, characterized for brain endothelial phenotype and largely employed as a model of human blood–brain barrier (BBB) function. Cytotoxicity was evaluated via MTT and LDH assays. Results: The quantification of CBD was carried out by HPLC-DAD and HPLC-MS/MS. Nanovesicles with Tween 20 (VS-CBD) exhibited smaller size (65.27 ± 1.27 nm vs. 90.7 ± 0.2), lower polydispersity (0.230 ± 0.005 vs. 0.295 ± 0.003), and higher stability compared to conventional liposomes (L-CBD). VS-CBD achieved high encapsulation efficiency (96.80 ± 0.96%) and recovery (99.89 ± 0.52%). Release studies showed sustained CBD release with Higuchi model fitting (R² = 0.9901). Both PAMPA-BBB and hCMEC/D3-BBB cell lines demonstrated an improved controlled permeability of the formulation compared to free CBD. Cytotoxicity tests confirmed the good biocompatibility of VS-CBD formulations. The addition of Tween 20 to nanovesicles enhanced CBD encapsulation, stability, and controlled release. Conclusions: These nanovesicles represent a promising strategy to improve CBD delivery to the brain, offering sustained therapeutic effects and reduced dosing frequency, potentially benefiting the treatment of neurological disorders.

A novel formulation based on nanostructured lipid carriers (NLCs) was developed to increase solubility and intestinal absorption of khellin. K-NLCs were prepared with stearic acid, hempseed oil, Brij S20, and Labrafil M 1944 CS, using the emulsification-ultrasonication method. Developed nanoparticles were chemically and physically characterized by liquid chromatography, light scattering techniques, and electron microscopy. The size, about 200 nm, was optimal for oral delivery, and the polydispersity index (around 0.26), indicated high sample homogeneity. Additionally, K-NLCs showed a spherical morphology without aggregation by microscopic analysis. The encapsulation efficiency of khellin was about 55%. In vitro release studies were carried out in media with different pH to mimic physiological conditions. K-NLCs were found to be physically stable in the simulated gastric and intestinal fluids, and they preserved about 70% of khellin after 6 h incubation. K-NLCs were also successfully lyophilized testing different lyoprotectants, and obtained freeze-dried K-NLCs demonstrated good shelf life over a month. Lastly, permeability studies on Caco-2 cells were performed to predict khellin passive diffusion across the intestinal epithelium, demonstrating that nanoparticles increased khellin permeability by more than two orders of magnitude. Accordingly, developed NLCs loaded with khellin represent a versatile formulation with good biopharmaceutical properties for oral administration, possibly enhancing khellin’s bioavailability and therapeutic effects.

The purpose of this study was to investigate the loading properties of the non-psychoactive cannabidiol (CBD) in a new nanostructured lipid carrier (NLC), evaluating its bioaccessibility in gastric and intestinal simulated physiological media. CBD has a low water solubility, as well as high instability in simulated physiological conditions and in the acidic media, which results in a very low bioavailability—less than 6%. NLCs containing CBD (10 mg/mL), Compritol 888 ATO, Lauroglycol 90, Labrafil 2125, Tween 20, and Poloxamer 188 were formulated. This resulted in them being suitable for oral administration because the size was less than 200 nm, polydispersity index 0.152, and ζ-potential −39.21 ± 1.89 mV. Recovery and encapsulation efficiency were 100% and 93%, respectively. After two hours of incubation in simulated gastric fluid (SGF), NLCs remained unchanged, protecting CBD from acidic medium. Indeed, CBD is also reported to be not stable in media with pH = 7.4 at 37 °C, but our studies evidenced that in the presence of the intestinal fluid, the NLC was digested and formed an emulsion, which can protect and preserve the CBD chemical structure, as confirmed by the 100% recovery found after six hours. Accordingly, CBD-loaded NLCs are a promising oral formulation that optimize bioaccessibility in the small intestine.

Resins are complex mixtures of natural constituents containing non-volatile and volatile terpenes, in combination with gums and polyphenols, used since ancient times for their medicinal properties. Current research has evidenced their therapeutic value with a plethora of activities. The main limits of resins and their constituents for their clinical use are low water solubility, poor stability and bioavailability. Therefore, nanovectors including vesicles, solid lipid nanoparticles, micelles, nanoemulsions, microemulsions and mesoporic nanoparticles have been investigated to optimize the biopharmaceutical properties after topical or oral administration of resins or fractions from them, including essential oils or single constituents. In this review, we report the results evidencing that developed nanovectors were able to entrap high amounts of resins or their components, modify the release properties, enhance their cellular uptake and penetration across biological barriers and optimize the biopharmaceutical properties. In addition, the resins or their fractions as enhancer penetration molecules can optimize the architecture and properties of nanovectors in their capacity to circumvent biological barriers. Although no clinical studies have been reported until now, nanovectors represent a huge platform for upgrading therapies and emerging new treatments of resins such as wound healing therapy.