Temperature-sensitive lyotropic liquid crystals as systems for transdermal drug delivery

Pluronic P123/DMSO Lyotropic Liquid Crystal for Incorporating Bioactive Substances for Topical Application

Lyotropic liquid crystals (LLCs) have attracted considerably growing interest in drug delivery applications over the last years. The structure of LLC matrices is complementary to cell membranes and provides an efficient, controlled, and selective release of drugs. In this work, a complex of experimental methods was used to characterize binary LLCs Pluronic P123/DMSO and triple LLC systems Pluronic P123/DMSO/Ibuprofen, which are interesting as transdermal drug delivery systems. Liquid crystalline, thermal, and rheological properties of LLCs were studied. Concentration and temperature areas of the lyomesophase existence were found, and phase transition enthalpies were evaluated. Intermolecular interactions among the components were studied by infrared (IR) spectroscopy. In vitro studies of Ibuprofen (Ibu) release from various LLCs allow differentiation of its release depending on the polymer content. Atomic force microscopy and contact angle methods were used to characterize the surface morphology of the hydrophobic membrane, which was used as a stratum corneum model, and also evaluate the adhesion work of the LLCs. A complex analysis of the results provided by these experimental methods allowed revealing correlations between the phase behavior and rheological characteristics of the LLCs and release kinetics of ibuprofen. The proposed biocompatible systems have considerable potential for a transdermal delivery of bioactive substances.

Recent Advances in the Development of Liquid Crystalline Nanoparticles as Drug Delivery Systems

Due to their distinctive structural features, lyotropic nonlamellar liquid crystalline nanoparticles (LCNPs), such as cubosomes and hexosomes, are considered effective drug delivery systems. Cubosomes have a lipid bilayer that makes a membrane lattice with two water channels that are intertwined. Hexosomes are inverse hexagonal phases made of an infinite number of hexagonal lattices that are tightly connected with water channels. These nanostructures are often stabilized by surfactants. The structure's membrane has a much larger surface area than that of other lipid nanoparticles, which makes it possible to load therapeutic molecules. In addition, the composition of mesophases can be modified by pore diameters, thus influencing drug release. Much research has been conducted in recent years to improve their preparation and characterization, as well as to control drug release and improve the efficacy of loaded bioactive chemicals. This article reviews current advances in LCNP technology that permit their application, as well as design ideas for revolutionary biomedical applications. Furthermore, we have provided a summary of the application of LCNPs based on the administration routes, including the pharmacokinetic modulation property.

Injectable In-Situ Forming Depot Based on PLGA and PLGA-PEG-PLGA for Sustained-Release of Risperidone: In Vitro Evaluation and Pharmacokinetics in Rabbits

In the current research, novel drug delivery systems based on in situ forming gel (ISFG) (PLGA-PEG-PLGA) and in situ forming implant (ISFI) (PLGA) were developed for one-month risperidone delivery. In vitro release evaluation, pharmacokinetics, and histopathology studies of ISFI, ISFG, and Risperdal CONSTA^® were compared in rabbits. Formulation containing 50% (w/w %) of PLGA-PEG-PLGA triblock revealed sustained release for about one month. Scanning electron microscopy (SEM) showed a porous structure for ISFI, while a structure with fewer pores was observed in the triblock. Cell viability in ISFG formulation in the first days was more than ISFI due to the gradual release of NMP to the release medium. Pharmacokinetic data displayed that optimal PLGA-PEG-PLGA creates a consistent serum level in vitro and in vivo through 30 days, and histopathology results revealed nearly slight to moderate pathological signs in the rabbit's organs. The shelf life of the accelerated stability test didn't affect the results of the release rate test and demonstrated stability in 24 months. This research confirms the better potential of the ISFG system compared with ISFI and Risperdal CONSTA^®, which would increase patients' compliance and avoid problems of further oral therapy.

Transdermal delivery of inflammatory factors regulated drugs for rheumatoid arthritis

Rheumatoid arthritis is a chronic autoimmune disease, with the features of recurrent chronic inflammation of synovial tissue, destruction of cartilage, and bone erosion, which further affects joints tissue, organs, and systems, and eventually leads to irreversible joint deformities and body dysfunction. Therapeutic drugs for rheumatoid arthritis mainly reduce inflammation through regulating inflammatory factors. Transdermal administration is gradually being applied to the treatment of rheumatoid arthritis, which can allow the drug to overcome the skin stratum corneum barrier, reduce gastrointestinal side effects, and avoid the first-pass effect, thus improving bioavailability and relieving inflammation. This paper reviewed the latest research progress of transdermal drug delivery in the treatment of rheumatoid arthritis, and discussed in detail the dosage forms such as gel (microemulsion gel, nanoemulsion gel, nanomicelle gel, sanaplastic nano-vesiclegel, ethosomal gel, transfersomal gel, nanoparticles gel), patch, drug microneedles, nanostructured lipid carrier, transfersomes, lyotropic liquid crystal, and drug loaded electrospinning nanofibers, which provide inspiration for the rich dosage forms of transdermal drug delivery systems for rheumatoid arthritis.

Lyotropic liquid crystal-based transcutaneous peptide delivery system: Evaluation of skin permeability and potential for transcutaneous vaccination

Transcutaneous drug delivery is a promising method in terms of drug repositioning and reformulation because of its non-invasive and easy-to-use features. To overcome the skin barrier, which is the biggest challenge in transcutaneous drug delivery, a number of techniques, such as microemulsion, solid-in-oil dispersions and liposomes, have been studied extensively. However, the low viscosity of these formulations limits drug retention on the skin and reduces patient acceptability. Although viscosity can be increased by adding a thickening reagent, such an addition often alters formulation nanostructures and drug solubility, and importantly, decreases skin permeability. In this study, a gel-like lyotropic liquid crystal (LLC) was used as a tool to enhance skin permeability. In particular, we prepared 1-monolinolein (ML)-based LLCs with different water contents. All LLCs significantly enhanced skin permeation of a peptide drug, an epitope peptide of melanoma, despite their high viscoelasticity. Fourier transform infra-red spectroscopic analysis of the skin surface treated with the LLCs revealed that the gyroid geometry more strongly interacted with the lamellar structure inside the stratum corneum (SC) than the diamond geometry. Finally, as the result of the in vivo tumor challenge experiment using B16F10 melanoma-bearing mice, the LLC with the gyroid geometry showed stronger vaccine effect against tumor than a subcutaneous injection. Collectively, ML-based LLCs, especially with the gyroid geometry, are a promising strategy to deliver biomacromolecules into skin. STATEMENT OF SIGNIFICANCE: Transcutaneous drug delivery is a promising method for drug repositioning and reformulation because of its non-invasive and easy-to-use features. To overcome the skin barrier, which is the biggest challenge in transcutaneous drug delivery, we used a gel-like lyotropic liquid crystal (LLC) as a novel tool to enhance skin permeability. In this paper, we demonstrated that an LLC with a specific liquid crystalline structure has the highest skin permeation enhancement effect for a peptide antigen as a model drug. Moreover, the peptide antigen-loaded LLC showed a vaccine effect that was comparable to a subcutaneous injection in vivo. This study provides a basis for designing a transcutaneous delivery system of peptide drugs with LLC.

Design of Swollen Lipidic Cubic Phase to Increase Transcutaneous Penetration of Biomacromolecules

Lipidic cubic phase (LCP) is a self-assembled system composed of lipids with interpenetrated aqueous channels, and its potential in drug delivery systems has been investigated. Although LCP was shown to improve transcutaneous penetration of hydrophilic molecules of up to 1203 Da so far, the transcutaneous delivery of larger molecules such as proteins has not been achieved. This is likely because proteins are usually larger than the aqueous channels of LCP (∼37.2 Å in diameter), which limits the molecular diffusion in LCP. In this report, we overcome this issue by adding N-octyl-β-d-glucopyranoside to glyceryl monooleate-water-based LCP to give swollen LCP (SLCP), which has larger aqueous channel diameters (∼65.6 Å). First, we systemically evaluated the effect of swelling on drug diffusion in LCP/SLCP. The release kinetics of various peptides and proteins whose sizes ranged from 9.14 to 55.28 Å in diameter were evaluated, and the diffusion coefficients (D) were calculated by the Fickian diffusion model. As expected, all peptides and proteins diffused faster in SLCP than in LCP. A more detailed analysis revealed a negative linear relationship between log D and the ratio of the radius of gyration of the proteins to the aqueous channel radius, indicating that swelling of a cubic nanostructure is an effective strategy to enhance D. Next, the skin penetration of proteins encapsulated in LCP and SLCP was evaluated. The skin penetration of ovalbumin (42.9 kDa), for example, was enhanced by SLCP but not by LCP, and a positive correlation between D and the amount of skin penetration was found. Collectively, this study provides an effective measure for designing LCP systems that enhance transcutaneous penetration of biomacromolecules.

Stability Evaluation of Lyotropic Liquid Crystalline Precursor for the Co-delivery of Chlorhexidine and Silver Nanoparticles

Sealing the therapeutic agents in the root canal is considered to be an essential step in root canal therapy. The lyotropic liquid crystalline precursor (LLCP) incorporated with chlorhexidine (CHX) and silver nanoparticles (Ag-NPs) has been confirmed as a promising candidate for root canal therapy in the previous study. Importantly, the stability of the LLCP system was a significant determinant for its therapeutic effect and further application. The objective of this study was to comprehensively investigate the stability of the LLCP incorporated with CHX and Ag-NPs. The oil-water partition coefficient of CHX and Ag-NPs was measured. The water absorption and the physical stability of drug-loaded LLCP solution were studied. Stability under high temperature, high humidity, and strong light irradiation was also investigated. The results demonstrated that CHX and Ag-NPs could be entrapped in the water channel of LLCP, indicating the low tendency of drugs leakage. The drug-loaded LLCP was a pseudoplastic fluid and it showed an excellent physical stability with a sedimentation rate of 0.981 and a settling time of 26~28 h. The payload of LLCP was confirmed to weaken the water absorption behavior, which facilitated its transformation to cubic liquid crystal. The stress testing under high temperature, high humidity, and strong light irradiation also manifested that the LLCP was stable when stored under moisture-proof condition. In conclusion, the developed LLCP incorporated with CHX and Ag-NPs was highly stable during storage and qualified for further application.