Characterization of a Liquid Crystal System for Sustained Release of a Peptide BMS-686117

Automation of liquid crystal phase analysis for SAXS, including the rapid production of novel phase diagrams for SDS-water-PIL systems

Lyotropic liquid crystal phases (LCPs) are widely studied for diverse applications, including protein crystallization and drug delivery. The structure and properties of LCPs vary widely depending on the composition, concentration, temperature, pH, and pressure. High-throughput structural characterization approaches, such as small-angle x-ray scattering (SAXS), are important to cover meaningfully large compositional spaces. However, high-throughput LCP phase analysis for SAXS data is currently lacking, particularly for patterns of multiphase mixtures. In this paper, we develop semi-automated software for high throughput LCP phase identification from SAXS data. We validate the accuracy and time-savings of this software on a total of 668 SAXS patterns for the LCPs of the amphiphile hexadecyltrimethylammonium bromide (CTAB) in 53 acidic or basic ionic liquid derived solvents, within a temperature range of 25-75 °C. The solvents were derived from stoichiometric ethylammonium nitrate (EAN) or ethanolammonium nitrate (EtAN) by adding water to vary the ionicity, and adding precursor ions of ethylamine, ethanolamine, and nitric acid to vary the pH. The thermal stability ranges and lattice parameters for CTAB-based LCPs obtained from the semi-automated analysis showed equivalent accuracy to manual analysis, the results of which were previously published. A time comparison of 40 CTAB systems demonstrated that the automated phase identification procedure was more than 20 times faster than manual analysis. Moreover, the high throughput identification procedure was also applied to 300 unpublished scattering patterns of sodium dodecyl-sulfate in the same EAN and EtAN based solvents in this study, to construct phase diagrams that exhibit phase transitions from micellar, to hexagonal, cubic, and lamellar LCPs. The accuracy and significantly low analysis time of the high throughput identification procedure validates a new, rapid, unrestricted analytical method for the determination of LCPs.

Formation of Self-Assembled Liquid Crystalline Nanoparticles and Absorption Enhancement of Ω-3s by Phospholipids and Oleic Acids

This study aimed to optimize and evaluate self-assembled liquid crystalline nanoparticles (SALCs) prepared from phospholipids and oleic acid for enhancing the absorption of Ω-3s. We explored the structure and optimal formulation of SALCs, which are composed of Ω-3 ethyl ester (Ω-3 EE), phospholipids, and oleic acid, using a ternary diagram and evaluated the improvement in Ω-3 dissolution, permeation, and oral bioavailability. The in vitro dissolution and pharmacokinetics of Ω-3 SALCs were compared with those of Omacor soft capsules (as the reference). The shape of the liquid crystal was determined according to the composition of phospholipids, oleic acids, and Ω-3s and was found to be in cubic, lamellar, and hexagonal forms. The dissolution rates of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) obtained from Ω-3 SALCs were 1.7 to 2.3-fold higher than those of the Omacor soft capsules. Furthermore, a pharmacokinetic study in male beagle dogs revealed that Ω-3 SALCs increased the oral bioavailability of Ω-3 EE by 2.5-fold for EPA and 3.1-fold for DHA compared with the reference. We found an optimal formulation that spontaneously forms liquid crystal-based nanoparticles, improving the bioavailability of EPA and DHA, not found in the existing literature. Our findings offer insight into the impact of nanoparticle phase on the oral delivery of oil-soluble drugs and provide a novel Ω-3 EE formulation that improves the bioavailability of EPA and DHA.

Fast understanding of phases and phase separation in liquid crystal drug delivery systems using deuterium solid-state NMR

Characterization of lipid based (SPC/GDO/H₂O) liquid crystal (LC) drug delivery system is non-trivial and highly complex, especially when multiple and intermediate phases are present. The phase behavior of such mixtures during hydration or delivery is still poorly understood and therefore, characterizing these systems is crucially important towards controlling their function and enhancing the understanding of their drug release behavior. Current work has established an easy way to identify liquid crystal phases and phase mixtures using deuterium (²H) solid-state nuclear magnetic (NMR) spectroscopy under static conditions without disrupting the three dimensional structure and phases, as magic-angle spinning (MAS) could lead to disruption of the phases. Small angle X-ray scattering (SAXS) technique and optical microscopy were also employed to corroborate the study.

A Novel Phytantriol-Based In Situ Liquid Crystal Gel for Vaginal Delivery

The purpose of this paper was to evaluate the potential of in situ liquid crystal (LC) gels based on phytantriol (PYT) for vaginal delivery. The PYT-based in situ liquid crystal gels (PILGs) were prepared by a vortex method using PYT, ethanol (ET), and water (in the ratio of 64:16:20, w/w). The internal structures of PILGs and cubic LC gels (formed by PILG phase conversion) were confirmed by crossed polarized light microscopy (PLM) and small-angle X-ray scattering (SAXS). And the rheological tests showed that PILGs had small viscosity and excellent fluidity. The viscosities of cubic LC gels were 4~5 orders of magnitude higher than PILGs. In vitro phase conversion experiment showed that PILGs required little vaginal fluid (64.56 μL/100 mg) and time (3.92 s) to transform to LC gels. Furthermore, cubic LC gels could reside in the vaginas for more than 12 h in vivo. The in vitro release revealed that sinomenine hydrochloride (SMH) could be sustained released from the cubic gels over a period of 144 h, which was prior to SMH solution and carbomer gels. An in vivo vaginal mucosa irritation study indicated that PILGs were nonirritant and might be suitable for various vaginal applications. In conclusion, PILGs might represent a potential vaginal delivery strategy to overcome the limitations of traditional treatments.

Some observations on the liquid crystalline and gel behaviors of aqueous dispersions of a prodrug

BMS-830216 is a diprotic acid prodrug of two pK_a values (<2 and 6.8) with high apparent solubility at pH ≥ 7. At ∼ pH 4 solutions of BMS-830216 appear to be surface active, in which their surface tension can be reduced from 72 to 65 dynes when its concentrations is above the critical aggregation concentration (CAC∼0.2 mM). Additionally, at this pH, BMS-830216 tends to form liquid crystalline phases (at ≥ 2 mg/mL) in acetate buffer when using tris salt. Furthermore, after raising the concentration beyond 20 mg/g, formation of gel-like dispersions was noted. These gel-like dispersions exhibited a strong elastic strength, significantly impacting the dissolution behavior of the tris salt. Mechanistically, it is likely that BMS-830216 tris salt in solution first forms a lamellar phase followed by formation of a gel phase at higher concentrations (≥20 mg/mL). As indicated by SAXS, the lamellar phase formed seems to have two d-spacing values (∼5 nm and ∼10 nm (weak), which seems to correspond to two molecules connected tail by tail (5 nm). Further investigation is needed for phase identification, as their properties can affect the physical behavior of BMS-830216 in the development of pharmaceutical dosage forms.

A Novel Phytantriol-Based Lyotropic Liquid Crystalline Gel for Efficient Ophthalmic Delivery of Pilocarpine Nitrate

The purpose of this paper was to investigate the potential of liquid crystalline (LC) gels for ophthalmic delivery, so as to enhance the bioavailability of pilocarpine nitrate (PN). The gels were prepared by a vortex method using phytantriol and water (in the ratio of 73:27 w/w). Their inner structures were confirmed by crossed polarized light microscopy, small-angle X-ray scattering, attenuated total reflectance-Fourier transform infrared spectrum, and rheology. The in vitro release studies revealed that PN could keep sustained release from the gels over a period of 12 h. The ex vivo apparent permeability coefficient of the gels demonstrated a 3.83-folds (P < 0.05) increase compared with that of eye drops. The corneal hydration levels of the gel maintained in the normal range of 79.46 ± 2.82%, hinting that the gel could be considered non-damaging and safe to the eyes. Furthermore, in vivo residence time evaluation suggested that a better retention performance of LC gel was observed in rabbit's eyes compared to eye drops. In vivo ocular irritation study indicated that LC gel was nonirritant and might be suitable for various eye applications. In conclusion, LC gels might represent a potential ophthalmic delivery strategy to overcome the limitations of eye drops.