Estudo da eficácia de encapsulação da Cinarizina em cubossomos não-iônicos: caracterização estrutural e citotóxica / Study of the encapsulation efficacy of Cinnarizine in non-ionic cubosomes: structural and cytotoxic characterization

Os cubossomos são partículas nanoestruturadas em forma de bicamada lipídica, bicontínuas e altamente curvadas, as quais devem ser estabilizadas por um polímero não-iônico, neste caso o Pluronic® F-127. Podem ser compostos por alguns tipos de lipídios específicos que possuem a capacidade de se auto associar em estruturas cúbicas quando estão em excesso de água, como o fitantriol (PHY) e a monoleína (GMO). Devido a sua estrutura única, cubossomos possuem um grande potencial para serem considerados como sistemas drug delivery. Os sistemas drug delivery são amplamente utilizados na pesquisa farmacêutica e em contextos clínicos para aumentar a eficácia de compostos utilizados para diagnóstico e de fármacos. No caso da cinarizina (CNZ), fármaco já aprovado para o tratamento de náuseas, vômitos e vertigens causadas pela doença de Ménière, existem inúmeros efeitos colaterais associados a sua baixa solubilidade. Desta forma, a encapsulação em cubossomos se torna uma abordagem promissora para resolver os problemas de atividade farmacológica relacionados ao fármaco. Neste trabalho, realizamos uma caracterização biofísica da interação da CNZ em cubossomos (contendo PHY ou myverol, MYV, sendo este composto por 80% de GMO). As técnicas biofísicas utilizadas foram: espalhamento de raios-X em baixos ângulos (SAXS), espalhamento dinâmico de luz (DLS), microscopia eletrônica de transmissão (TEM), crio microscopia eletrônica de transmissão (Crio-TEM), análise de rastreamento de nanopartículas (NTA) e potencial zeta. A cromatografia líquida de alta eficiência (HPLC) foi realizada para verificar a porcentagem de eficiência de encapsulação (%EE) da CNZ nos cubossomos, enquanto que a citotoxicidade foi avaliada em eritrócitos através da análise da atividade hemolítica. Inicialmente, a influência de diferentes solventes (acetona, clorofórmio, etanol e octano) nas propriedades estruturais de cubossomos de PHY foi investigada, a fim de se minimizar os efeitos do solvente utilizados para a encapsulação da CNZ. Para amostras com acetona, descobriu-se que apenas altas concentrações tiveram influência na estrutura cristalográfica das nanopartículas, sendo o resultado foi totalmente reversível após 24h. O etanol fez com que o parâmetro de rede aumentasse de 10-15%. O clorofórmio e o octano tiveram efeitos diferentes sobre cubossomos de PHY em comparação com a acetona e o etanol; ambos induziram uma transição cúbico-hexagonal-micelar. Posteriormente, constatamos que as nanopartículas de PHY e MYV apresentaram diferentes estruturas cristalográficas, sendo elas Pn3m e Im3m, respectivamente. Devido a problemas com a baixa solubilidade de CNZ em PHY os estudos para esse lipídio foram suspensos. Nos testes para cubossomos de MYV ao incorporar a CNZ foi observado uma alteração da estrutura cúbica de Im3m para Pn3m e os valores dos parâmetros de rede se alteraram de acordo com a estrutura cristalina encontrada, porém os valores não apresentaram diferenças significativas de tamanho quando se trata da mesma estrutura, sugerindo que a CNZ não interferiu no parâmetro de rede. Os tamanhos das nanopartículas apresentaram uma população monodispersa com ~200 nm. DLS mostrou uma interferência da CNZ no tamanho dos cubossomos, variando de forma diretamente proporcional a concentração de CNZ na amostra, enquanto as técnicas de NTA e microscopia apresentaram nanopartículas de tamanhos bastante variados, mas independente da interferência da CNZ. A encapsulação de CNZ também foi dosada por HLPC em cubossomos de MYV, obtendo um limite superior de 0,6 mg/mL. A atividade citotóxica dos cubossomos foi testada em eritrócitos, revelando uma taxa de hemólise bastante inferior em cubossomos com CNZ em relação a cubossomos puros. Acreditamos que os cubossomos podem sim ser utilizados como sistemas carreadores de CNZ

Cubosomes are nanostructured particles in the form of a lipid bilayer, bicontinuous and highly curved, which must be stabilized by a non-ionic polymer, in this case Pluronic® F-127. They can be composed of some types of specific lipids that have the ability to self-associate in cubic structures when they are in excess of water, such as phytantriol (PHY) and monolein (GMO). Due to their unique structure, cubosomes have a great potential to be considered as drug delivery systems. Drug delivery systems are widely used in pharmaceutical research and clinical settings to increase the efficacy of compounds used for diagnostics and drugs. In the case of cinnarizine (CNZ), a drug already approved for the treatment of nausea, vomiting and vertigo caused by Ménière's disease, there are numerous side effects associated with its low solubility. Thus, cubosomal encapsulation becomes a promising approach to solve drug-related problems of pharmacological activity. In this work, we performed a biophysical characterization of the CNZ interaction in cubosomes (containing PHY or myverol, MYV, which is composed of 80% GMO). The biophysical techniques used were: low angle X-ray scattering (SAXS), dynamic light scattering (DLS), transmission electron microscopy (TEM), cryo transmission electron microscopy (Crio-TEM), nanoparticle tracking analysis (NTA) and zeta potential. High performance liquid chromatography (HPLC) was performed to verify the percentage of encapsulation efficiency (%EE) of CNZ in cubosomes, while cytotoxicity was evaluated in erythrocytes by analyzing the hemolytic activity. Initially, the influence of different solvents (acetone, chloroform, ethanol and octane) on the structural properties of PHY cubosomes was investigated in order to minimize the effects of the solvent used for the encapsulation of CNZ. For samples with acetone, it was found that only high concentrations had an influence on the crystallographic structure of the nanoparticles, with the result being fully reversible after 24h. Ethanol caused the network parameter to increase by 10-15%. Chloroform and octane had different effects on PHY cubosomes compared to acetone and ethanol; both induced a cubic-hexagonal-micellar transition. Later, we found that PHY and MYV nanoparticles presented different crystallographic structures, being Pn3m and Im3m, respectively. Due to problems with the low solubility of CNZ in PHY, studies for this lipid were suspended. In the tests for MYV cubosomes when incorporating CNZ, a change in the cubic structure from Im3m to Pn3m was observed and t he lattice parameters changed according to the crystal structure found, but the differences observed were not significant when it comes to the same structure, suggesting that the CNZ did not interfere with the network parameter. The nanoparticle sizes showed a monodisperse population with ~200 nm. DLS showed an interference of CNZ in the size of the cubosomes, varying directly proportionally to the concentration of CNZ in the sample, while NTA and microscopy techniques showed nanoparticles of widely varying sizes, but independent of CNZ interference. CNZ encapsulation was also dosed by HLPC in MYV cubosomes, obtaining an upper limit of 0.6 mg/ml. The cytotoxic activity of cubosomes was tested in erythrocytes, revealing a much lower rate of hemolysis in cubosomes with CNZ compared to pure cubosomes. We believe that cubosomes can indeed be used as CNZ carrier systems

Recent advances in drug delivery applications of cubosomes, hexosomes, and solid lipid nanoparticles

The use of lipid nanocarriers for drug delivery applications is an active research area, and a great interest has particularly been shown in the past two decades. Among different lipid nanocarriers,

Preparation of propranolol hydrochloride cubosomes by pH gradient method / 药学实践杂志

Objective To prepare propranolol hydrochloride loaded cubosomes (PPL-Cubs) with high entrapment efficiency. Methods PPL-Cubs was prepared by pH gradient method. Pressure and cycles of high pressure homogenization, dosage of glyceryl monooleate and poloxamer 407 were optimized to prepare blank cubosomes with particle size and polydispersity index as the indexes. The influences of various factors, including exterior pH values, internal pH values, the ratio of carrier to drug, particle size and polydispersity index of blank cubosomes, incubation temperature and time, and drug concentration on the entrapment efficiency were investigated. Results The blank cubosomes with small particle size and polydispersity index was prepared under homogenization conditions of 900 bar for 7 cycles, glyceryl monooleate dosage of 25%, and poloxamer 407 dosage of 5%. PPL-Cubs showed high entrapment efficiency with exterior pH value of 8.5, internal pH value of 3.0, ratio of carrier to drug of 6∶1, incubation temperature of 20 ℃, and incubation time of 15 min, and drug concentration of 1%. The particle size and polydispersity index of blank cubosomes showed no influence on entrapment efficiency. Conclusion PPL-Cubs with high entrapment efficiency could be prepared under the pH gradient method.

Formulation and characterization of Liquid Crystalline Hydrogel of Agomelatin: In vitro and Ex vivo evaluation.

Objective: The aim of this investigation was the development and characterization of Agomelatin-loaded liquid crystalline (AM-LC) nanoparticles for improved topical application. Methods: AM-LC was formulated with the glyceryl monooleate (GMO) and poloxamer 407 as structure forming agent (lipid) and surfactant respectively, by using emulsification of GMO and poloxamer in water using a hydrotrope (Cubosomes) formation method. The obtained dispersion was characterized for particle size, PDI, zeta potential, entrapment efficiency, surface morphology, in vitro studies. Further, conversion optimised formulation in to cubic gel by incorporating 0.5% w/w of carbopol 934P. The prepared gel was characterized by rheological measurements, surface pH and ex vivo permeation studies through the rat skin. Results: The average particle size of formulations was ranging from 187.6±3.97nm to 225.8±7.54nm and ZP from -14.5±4.65 to -23.5±3.86mV. In vitro drug release from cubosomes exhibited sustained release profile and the optimized formulation (F2) showed cumulative drug release of 83.96±2.43% during 24h. Transmission electron microscopic photographs confirmed that the formed liquid crystalline nanoparticles were cubic in shape. Results suggested that cubic gel exhibited a retarded release rate (53.5 ± 3.21%) than the control gel (95.33 ± 2.28%) containing 0.1% drug solution. Conclusion: The obtained results indicated that cubic gel would be a promising carrier for topical delivery of agomelatin into and across the skin.

In vitro and in vivo evaluation of cubosomes containing 5-fluorouracil for liver targeting

The objective of this study was to prepare cubosomal nanoparticles containing a hydrophilic anticancer drug 5-fluorouracil (5-FU) for liver targeting. Cubosomal dispersions were prepared by disrupting a cubic gel phase of monoolein and water in the presence of Poloxamer 407 as a stabilizer. Cubosomes loaded with 5-FU were characterized in vitro and in vivo. In vitro, 5-FU-loaded cubosomes entrapped 31.21% drug and revealed nanometer-sized particles with a narrow particle size distribution. In vitro 5-FU release from cubosomes exhibited a phase of rapid release of about half of the entrapped drug during the first hour, followed by a relatively slower drug release as compared to 5-FU solution. In vivo biodistribution experiments indicated that the cubosomal formulation significantly (P<0.05) increased 5-FU liver concentration, a value approximately 5-fold greater than that observed with a 5-FU solution. However, serum serological results and histopathological findings revealed greater hepatocellular damage in rats treated with cubosomal formulation. These results demonstrate the successful development of cubosomal nanoparticles containing 5-FU for liver targeting. However, further studies are required to evaluate hepatotoxicity and in vivo antitumor activity of lower doses of 5-FU cubosomal formulation in treatment of liver cancer.

Cubosome: A novel approach for nanotechnology.

Cubosome dispersions are thermodinamically stable, bioadhesive and biocompatible.Because of their properties, cubosome are versatile systems, administrable by different ways such as orally, percutaneously and parenterally. The discovery of cubosomes is a unique story and spans the fields of food science, differential geometry, biological membranes, and digestive processes. Despite the early realization of their potential, the manufacture of cubosomes on a large scale embodied difficulty because of their complex phase behaviour and viscous properties. Contributions to cubosome research have come from the fields of biology, material science, medicine, and mathematics and much is known about their formation and properties. At the center of much of the discovery and innovation is the technique of cryo-transmission electron microscopy. Another cubosome advantage is related to the simple production procedure and the chemico-physical stability. With respect to liposome, cubosome possesses a larger ratio between the bilayer area and the particle volume and a larger breaking resistance. Cubosome structure by means of electron microscopy, “light scattering”, x-ray and “NMR”, nevertheless few researchers have been studying the potential of cubosome as “delivery systems”.

Cubosomes as drug delivery system: Recent advance / 第二军医大学学报

Cubosomes are self-assembled nanostructured particles formed by aqueous lipid and surfactant systems. Cubosomes are thermodynamically stable; they have a structure like "honeycombed" with bicontinuous domains of water and lipid in which surfactant assembles into bilayers and twisted into a three dimension, periodic, and minimal surface, forming a tightly packed structure. The properties of cubosomes, such as its unique bicontinuous cubic phase liquid crystals, its ability to solubilize hydrophobic, hydrophilic, and amphiphilic molecules at the same time, its biodegradability by simple enzyme action, its strong bioadhesion ability, and its simple preparation, make them a promising vehicle for drug delivery. Based on recent reports, this review introduces the structure, preparation, exosyndrome and drug delivery potential of cubosomes.

Ocular pharmacokinetics of dexamethasone cubosomes in rabbit aqueous humor / 中国药科大学学报

Aim: To prepare novel cubosome system for effective ocular drug delivery with dexamethasone(DEX) as model drug, and investigate its pharmacokinetic profile in rabbit aqueous humor. Methods: DEX cubosomes was prepared by the method of high-pressure homogenization, and its particle size was determined by the laser particle sizer, and the microstructure observed by cryo-TEM. In addition, Draize method was used to evaluate the ocular irritation of DEX cubosomes. Finally, aqueous humor microdialysis was utilized to evaluate its pharmacokinetics in rabbits. Results: Average diameter of DEX cubosomes was about 200 nm, and the cubic structure of the particles was evident under the cryo-TEM. It was indicated by Draize scores that this dosage form exhibited excellent ocular tolerance. Results of pharmacokinetic profiles in aqueous humor showed that AUC_(0→240) and c_(max) of the rabbit group administered with DEX cubosomes were significantly higher than those of the control group( DEX sodium phosphate eye drops), with AUC_(0→240) of the formulation Fl( 10% oil content) and F2(20% oil content) is being about 1. 8 and 2. 9 times higher than those of the control group, respectively( P <0. 05). Conclusion: The novel ocular drug delivery system of DEX cubosomes was capable of increasing significantly the drug concentration in aqueous humor, and improving the ocular bioavailability.