(T1030-04-21) Lyotropic Liquid Crystal Drug Delivery System: Cubosome Encapsulate Cromolyn Sodium for Oral Delivery

Purpose: In this study, a cubic phase of lyotropic liquid crystal (cubosomes) encapsulated water soluble cromolyn sodium (CS) - mast cell stabilizers- to enhance through lymphatic uptake thus improving its oral bioavailability.

Methods: 1) Preparation of CS-loaded cubosomes - Cubosomes were prepared by hydrating a mixture of monoolein and different ratios of poloxamer 407 (P407). First, the oil phase mixture of monoolein and P407 were completely melted at 70 degrees Celsius in a hot water bath. The mixture was then added dropwise to CS solution at the same temperature, and formed coarse dispersions. The formed dispersions were left stabilizing at room temperature for 48 hours. After equilibration, finally, the coarse dispersions were then homogenized at 9500 rpm for 2 hours resulting in a milk-like cubosomal gel. 2) In vitro characterization of cubosomes - Morphological examination was conducted using a transmission electron microscope (TEM). Particle size, zeta potential, and polydispersity index analysis were additionally performed. The entrapment efficiency (% EE) of different formulations of stabilizers was determined by ultrafiltration, with molecular weight cutoff (MWCO) of 100,000 kD. Drug release profile from cubosomes was determined using the dialysis bag method in pH 7.4. Samples (1 mL) were withdrawn at predetermined time intervals and replaced with the same volume of phosphate buffer. Ex-vivo intestinal permeation of CS-loaded cubosomes using modified Ussing chamber method was compared with that of CS solution

Results: 1) TEM images of cubosomes - Transmission electron microscopy images of prepared cubosomes are shown in Figure 1. The images showed cubic structures of the prepared cubosomes. Particle size range is 100 nm ensuring that all the prepared cubosomes were nanosized. Polydispersity index values were below 0.3 and zeta potential values around ± 30 are acceptable for stability. 2) Entrapment efficiency - The entrapment efficiency (% EE) of different formulations of stabilizers are shown in Table 1. Tween 80, Cremophor ELP, Labrasol and D-α-tocopheryl polyethylene glycol succinate (Vitamin E TPGS) was investigated using the optimum ratio either alone or in combination with P407. 3) Drug release profile - Drug release profile showed sustained release of CS-loaded cubosomes. While it took less than 2 hours to reach 100% cumulative amount of drug release for the drug solution, approximately 80% of drug release from cubosomes after 24 hours. 4) Ex vivo intestinal permeation - The results of ex-vivo intestinal permeation are shown in Figure 2. It was revealed that the permeability of cubosomes was significantly higher than that of the CS solution. In addition, other bioactive surfactants also enhanced the CS permeability.

Conclusion: This study focuses on the application of cubosomes which can be considered as a promising lipid nanoparticle strategy for drug delivery. Cubosomes showed an ability to encapsulate both hydrophobic and hydrophilic agents, due to their unique structures of lipid bilayer membranes. Pharmacokinetic and pharmacodynamic profiles of cubosomes, or the optimized ratio of water and oil phase because of the cubic phase stability will be discussed in further studies.

References: 1. Patel, R. R., et al. (2016). "Highly water-soluble mast cell stabilizer-encapsulated solid lipid nanoparticles with enhanced oral bioavailability." Journal of Microencapsulation 33(3): 209-220.
2. Huang, Y. and S. Gui (2018). "Factors affecting the structure of lyotropic liquid crystals and the correlation between structure and drug diffusion." RSC Advances 8(13): 6978-6987.
3. Chen, Y., et al. (2014). "Cubic and hexagonal liquid crystals as drug delivery systems." BioMed research international: 815981-815981.

Acknowledgements:

Funding: This work was supported by the Mid-Career Researcher Program (No. NRF-2021R1A2C2008834) and Basic Research Infrastructure Support Program (University-Centered Labs-2018R1A6A1A03023718) through the National Research Foundation of Korea (NRF) funded by the Korean government (MSIT)



Table 1. Entrapment efficiency (mean, n = 3) of CS loaded monoolein cubosome


Figure 2. The results of ex vivo intestine permeation tests of CS solution and CS loaded cubosome formulation.