In vitro release of hydrophobic drugs by oleogel rods with biocompatible gelators

Oleogels for the ocular delivery of epalrestat: formulation, in vitro, in ovo, ex vivo and in vivo evaluation

The ocular administration of lipophilic and labile drugs such as epalrestat, an aldose reductase inhibitor with potential for diabetic retinopathy treatment, demands the development of topical delivery systems capable of providing sufficient ocular bioavailability. The aim of this work was to develop non-aqueous oleogels based on soybean oil and gelators from natural and sustainable sources (ethyl cellulose, beeswax and cocoa butter) and to assess their reproducibility, safety and efficiency in epalrestat release and permeation both ex vivo and in vivo. Binary combinations of gelators at 10% w/w resulted in solid oleogels (oleorods), while single gelator oleogels at 5% w/w remained liquid at room temperature, with most of the oleogels displaying shear thinning behavior. The oleorods released up to 4 µg epalrestat per mg of oleorod in a sustained or burst pattern depending on the gelator (approx. 10% dose in 24 h). The HET-CAM assay indicated that oleogel formulations did not induce ocular irritation and were safe for topical ocular administration. Corneal and scleral ex vivo assays evidenced the permeation of epalrestat from the oleorods up to 4 and 2.5 µg/cm2 after six hours, respectively. Finally, the capacity of the developed oleogels to sustain release and provide significant amounts of epalrestat to the ocular tissues was demonstrated in vivo against aqueous-based niosomes and micelles formulations loaded with the same drug concentration. Overall, the gathered information provides valuable insights into the development of oleogels for ocular drug delivery, emphasizing their safety and controlled release capabilities, which have implications for the treatment of diabetic neuropathy and other ocular conditions.

Topical Formulations Based on Ursolic Acid-Loaded Nanoemulgel with Potential Application in Psoriasis Treatment

Psoriasis is a chronic disorder that causes a rash with itchy, scaly patches. It affects nearly 2-5% of the worldwide population and has a negative effect on patient quality of life. A variety of therapeutic approaches, e.g., glucocorticoid topical therapy, have shown limited efficacy with systemic adverse reactions. Therefore, novel therapeutic agents and physicochemical formulations are in constant need and should be obtained and tested in terms of effectiveness and minimization of side effects. For that reason, the aim of our study was to design and obtain various hybrid systems, nanoemulgel-macroemulsion and nanoemulgel-oleogel (bigel), as vehicles for ursolic acid (UA) and to verify their potential as topical formulations used in psoriasis treatment. Obtained topical formulations were characterized by conducting morphological, rheological, texture, and stability analysis. To determine the safety and effectiveness of the prepared ursolic acid carriers, in vitro studies on human keratinocyte cell-like HaCaT cells were performed with cytotoxicity analysis for individual components and each formulation. Moreover, a kinetic study of ursolic acid release from the obtained systems was conducted. All of the studied UA-loaded systems were well tolerated by keratinocyte cells and had suitable pH values and stability over time. The obtained formulations exhibit an apparent viscosity, ensuring the appropriate time of contact with the skin, ease of spreading, soft consistency, and adherence to the skin, which was confirmed by texture tests. The release of ursolic acid from each of the formulations is followed by a slow, controlled release according to the Korsmeyer-Peppas and Higuchi models. The elaborated systems could be considered suitable vehicles to deliver triterpene to psoriatic skin.

Recent advances in lipid-based long-acting injectable depot formulations

Long-acting injectable (LAIs) delivery systems sustain the drug therapeutic action in the body, resulting in reduced dosage regimen, toxicity, and improved patient compliance. Lipid-based depots are biocompatible, provide extended drug release, and improve drug stability, making them suitable for systemic and localized treatment of various chronic ailments, including psychosis, diabetes, hormonal disorders, arthritis, ocular diseases, and cancer. These depots include oil solutions, suspensions, oleogels, liquid crystalline systems, liposomes, solid lipid nanoparticles, nanostructured lipid carriers, phospholipid phase separation gel, vesicular phospholipid gel etc. This review summarizes recent advancements in lipid-based LAIs for delivering small and macromolecules, and their potential in managing chronic diseases. It also provides an overview of the lipid depots available in market or clinical phase, as well as patents for lipid-based LAIs. Furthermore, this review critically discusses the current scenario of using in vitro release methods to establish IVIVC and highlights the challenges involved in developing lipid-based LAIs.

Non-aqueous formulations in topical ocular drug delivery - a paradigm shift?

Topical eyedrop application is the preferred route for drug delivery to anterior segment tissues; however, the challenge of overcoming the eye's anatomical and physiological barriers while minimising tissue toxicity has restricted developments in this field. Aqueous vehicles have traditionally been used, which typically require several additives and preservatives to achieve physiologically compatible and sterile eyedrops, elevating their toxicity potential. Non-aqueous vehicles have been suggested as efficient alternatives for topical drug delivery as they can address many of the limitations associated with conventional aqueous eyedrops. However, despite their obvious advantages, non-aqueous eyedrops remain poorly researched and few non-aqueous formulations are currently available in the market. This review challenges the conventional hypothesis that aqueous solubility is a prerequisite to ocular drug absorption and establishes a rationale for using non-aqueous vehicles for ocular drug delivery. Recent advances in the field have been detailed and future research prospects have been explored, pointing towards a paradigm shift in eyedrop formulation in the near future.

Nanofiber-coated implants: Development and safety after intravitreal application in rabbits

Intravitreal injections are the preferred choice for drug administration to the posterior segment of the eye. However, the required frequent injections may cause complications to the patient and low adherence to the treatment. Intravitreal implants are able to maintain therapeutic levels for a long period. Biodegradable nanofibers can modulate drug release and allow the incorporation of fragile bioactive drugs. Age-related macular degeneration is one of the world major causes of blindness and irreversible vision loss. It involves the interaction between VEGF and inflammatory cells. In this work we developed nanofiber-coated intravitreal implants containing dexamethasone and bevacizumab for simultaneously delivery of these drugs. The implant was successfully prepared and the efficiency of the coating process was confirmed by scanning electron microscopy. Around 68% of dexamethasone was released in 35 days and 88% of bevacizumab in 48hs. The formulation presented activity in the reduction of vessels and was safe to the retina. It was not observed any clinical or histopathological change, neither alteration in retina function or thickness by electroretinogram and optical coherence tomography during 28 days. The nanofiber-coated implants of dexamethasone and bevacizumab may be considered as a new delivery system that can be effective for the treatment of AMD.

Edible oleogels stabilized solely by stigmasterol: effect of oil type and gelator concentration

BACKGROUND

Phytosterols are considered to be one of the most promising gelators for obtaining oleogel because of their additional health benefits and natural coexist with vegetable oils. Previous studies have confirmed that individual phytosterols are not capable of structuring vegetable oils unless they act synergistically with other components. However, based on the self-assembly properties of stigmasterol (ST) in organic solvents, we speculate that it can also structure vegetable oils as a gelator alone.

RESULTS

For the first time, the present study confirmed the feasibility of using ST alone as a gelator for structuring of vegetable oils, including rapeseed oil (RSO), olive oil (OLO) and flaxseed oil (FSO). RSO had the lowest ST gelation concentration (4%, w/w), and the oil-binding capacity and firmness value of the oleogels were the highest. The rheological results showed that all the samples were gelatinous (G' > G″). The results of differential scanning calorimeter and X-ray diffraction further confirmed that the properties of RSO-based oleogels are superior to those prepared by OLO and FSO. The microscopic results also confirmed that the crystal structure of RSO oleogels was more uniform, smaller and more densely distributed.

CONCLUSION

The structural properties of the oleogels were positively correlated with the ST concentration, and various analysis indicators showed that the performance of the oleogel based on RSO was better than that of OLO and FSO. In summary, the present study used ST as a gelator to successfully prepare oleogels with excellent properties, which provides a feasible reference for researchers in related fields. © 2022 Society of Chemical Industry.

Preparation and Characterization of Novel Oleogels Using Jasmine Floral Wax and Wheat Germ Oil for Oral Delivery of Curcumin

Oleogels (OGs) have gained a lot of interest as a delivery system for a variety of pharmaceuticals. The current study explains the development of jasmine floral wax (JFW) and wheat germ oil (WGO)-based OGs for oral drug (curcumin) delivery application. The OGs were made by dissolving JFW in WGO at 70 °C and cooling it to room temperature (25 °C). The critical gelation concentration of JFW that induces the gelation of WGO was found to be 10% (w/w). The OGs were characterized using various techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), microscopic analysis, and mechanical test. XRD data indicated that JFW influences the crystallinity of the OGs. Among the prepared OGs, OG 17.5 showed higher crystallization in the series. Optical microscopic studies demonstrated the formation of fiber structures due to the entanglement of crystals whereas, polarized light micrographs suggested the formation of spherulites or clustered crystallite structures. The mechanical properties of the OGs increased linearly with the increase in the JFW concentration. Curcumin-loaded OGs were examined for their controlled release applications. In summary, the developed OGs were found to have the necessary features for modulating the oral delivery of curcumin.

A Review of Potential Use of Amazonian Oils in the Synthesis of Organogels for Cosmetic Application

New strategies for the delivery of bioactives in the deeper layers of the skin have been studied in recent years, using mainly natural ingredients. Among the strategies are organogels as a promising tool to load bioactives with different physicochemical characteristics, using vegetable oils. Studies have shown satisfactory skin permeation, good physicochemical stability mainly due to its three-dimensional structure, and controlled release using vegetable oils and low-molecular-weight organogelators. Within the universe of natural ingredients, vegetable oils, especially those from the Amazon, have a series of benefits and characteristics that make them unique compared to conventional oils. Several studies have shown that the use of Amazonian oils brings a series of benefits to the skin, among which are an emollient, moisturizing, and nourishing effect. This work shows a compilation of the main Amazonian oils and their nutraceutical and physicochemical characteristics together with the minority polar components, related to health benefits, and their possible effects on the synthesis of organogels for cosmetic purposes.

Design and In Vitro Evaluation of a Slow-Release Intraocular Implant of Betamethasone

Posterior eye diseases are a common cause of vision problems in developing countries, which have encouraged the development of new treatment models for these degenerative diseases. Intraocular implants are one of the drug delivery systems to the posterior region of the eye. Using these implants, the blood-eye barrier can be bypassed; the complications caused by repeated in vitro administrations can be eliminated, and smaller amounts of the drug would be used during the treatment process. Meanwhile, biodegradable implants have received more attention due to their biodegradable structure and the lack of need for re-surgery to remove the rest of the system from the eye. The aim of this study is to employ biodegradable implants composed of polyethylene glycol (PEG) and 3-hydroxybutyrate-co-3-hydroxyvalerat (PHBV) to deliver betamethasone to the back of the eye in the treatment of retinopathy. PHBV polymer has been selected as the main polymer with a certain ratio of drug to polymer for fabrication of enamel and different amounts of PEG with three molecular weights used as pore generators to control drug release over a period of time. Based on the analysis of the results of differential scanning calorimetry (DSC) and FTIR spectroscopy, none of the polymers were degraded in the temperature range of the manufacturing process, and among betamethasone derivatives, the best option for implant preparation is the use of its basic form. Drug release studies over a period of three months showed that implants containing PHBV HV2% and PEG 6000 had a more appropriate release profile.

Graphene Oxide Increases Corneal Permeation of Ciprofloxacin Hydrochloride from Oleogels: A Study with Cocoa Butter-Based Oleogels

In this work, oleogels of cocoa butter (CB), rice bran oil (RBO), and graphene oxide (GO) were prepared. The prepared oleogels were subjected to various characterization techniques such as bright-field microscopy, X-ray diffraction (XRD), crystallization kinetics, differential scanning calorimetry (DSC), and mechanical studies. The influence of increasing GO content on the in vitro drug release and ex vivo corneal permeation of the model drug (ciprofloxacin HCl-CPH) from the oleogels was also investigated. Bright-field micrographs showed that increment in GO content reduced the size of the globular particles of CB. XRD analysis revealed that CB was crystallized in its β' and β polymorphic forms in the oleogels, which was in agreement with thermal studies. The mechanical characterization demonstrated that the presence of GO improved the elastic nature and stress-bearing properties of the oleogels. Moreover, GO altered the crystallization kinetics of CB in the oleogels in a composition-dependent manner. The in vitro release of CPH from the oleogels occurred through either Fickian diffusion or fat network relaxation or a combination thereof. Furthermore, the inclusion of GO enhanced the ex vivo permeation of CPH molecules across the caprine cornea. Hence, we concluded that the prepared oleogels could be explored as potential delivery systems for ophthalmic applications.

Transdermal Delivery of Gold Nanoparticles by a Soybean Oil-Based Oleogel under Iontophoresis

Developing a facile mechanism for transporting nanoparticles across the whole skin by overcoming the stratum corneum is a challenging task. Herein, a stimuli-responsive and noninvasive transport of gold nanoparticles (AuNPs) has been reported through the fabrication of AuNP-incorporated soybean oil-based oleogels (AuG) using stearic acid as a gelator. A series of AuG was formulated by incorporating different proportions of AuNPs and a fixed amount of ciprofloxacin hydrochloride (drug) to establish that the composition with the highest concentration of AuNP (d-AuG4) was associated with the best iontophoretic response, validated via the corresponding in vitro drug release under AC field-induced iontophoresis. The sample d-AuG4 exhibited both drug and AuNP permeation across the whole pig ear skin thickness within as early as 1 h under the iontophoresis condition. With relevant control experiments, it was shown that the transport of AuNPs through the stratum corneum tissue and across the whole skin was possible upon the simultaneous fulfillment of two conditions: the presence of a skin permeation enhancer (stearic acid) within the oleogel and iontophoresis. While the literature reported that the permeation time for any free inorganic nanoparticle through the full-skin thickness varied within a few days, the permeation enhancement technique developed here reduced the corresponding delivery time for the AuNPs to a few hours. The extent of AuNP permeation that occurred in the microgram (per cm^-2) scale was found to be affected by the duration of iontophoresis, suggesting that AuNPs' rapid transdermal entry can be simultaneously triggered and modulated by iontophoretic conditions.