Cubic liquid crystalline nanoparticles containing a polysaccharide from Ulva fasciata with potent antihyperlipidaemic activity

The present study involves the preparation of cubic liquid crystalline nanoparticles (cubsomes) for liver targeting to assess the potential of a formulated bioactive polysaccharide isolated from the hot aqueous extract of Ulva fasciata as an alternative natural agent with anti-hyperlipidaemic activity. Cubosomal nanoparticles were prepared by disrupting the cubic gel phase of the polysaccharide and water in the presence of a surfactant. Different lipid matrices and stabilizers were tested. All the formulations were in the nanosize range and showed sufficient negative charge to inhibit the aggregation of the cubosomes. Drug entrapment efficiencies (EEs%) were determined and in vitro release studies were performed. Transmission electron microscopy (TEM) and differential scanning calorimetry were used to analyze the loaded cubosomal nanoparticles containing glyceryl monostearate (GMO 2.25?g), poloxamer 407 (0.25?g) and 50?mg of the polysaccharide. A preclinical study comparing the cubic liquid crystalline nanoparticles containing polysaccharide to fluvastatin as a reference drug in hyperlipidaemic rats was conducted. The rats treated with the polysaccharide- loaded cubosomes showed significant decreases in total cholesterol (TC), triglycerides (TG) and total lipid (TL) compared to the untreated HL rats. In addition, oxidative stress and antioxidant biomarkers were measured in the HL rats. Compared to the untreated HL rats, the cubosome treated rats showed a significant reduction in malondialdehyde (MDA), whereas insignificant changes were detected in nitric oxide (NO), glutathione (GSH) levels and total antioxidant capacity (TAC). Further, vascular and intercellular adhesion molecules (VCAM, ICAM), and myeloperoxidase were demonstrated. A histopathological examination was conducted to study the alterations in histopathological lesions and to document the biochemical results. In conclusion, this study demonstrates the superiority of using a natural lipid regulator such as polysaccharide loaded cubosomes instead of fluvastatin.     

Preparation of phytantriol cubosomes by solvent precursor dilution for the delivery of protein vaccines

Different delivery strategies to improve the immunogenicity of peptide/protein-based vaccines are currently under investigation. In this study, the preparation and physicochemical characterisation of cubosomes, a novel lipid-based particulate system currently being explored for vaccine delivery, was investigated. Cubosomes were prepared from a liquid precursor mixture containing phytantriol or glycerylmonooleate (GMO), F127 for particle stabilisation, and a hydrotrope (ethanol or polyethylene glycol (PEG₂₀₀) or propylene glycol (PG)). Several liquid precursors were prepared, and the effect of varying the concentrations of F127 and the hydrotrope on cubosome formation was investigated. Formulations were prepared by fragmentation for comparison. The model protein ovalbumin (Ova) was also entrapped within selected formulations. Submicron-sized particles (180-300 nm) were formed spontaneously upon dilution of the liquid precursors, circumventing the need for the preformed cubic phase used in traditional fragmentation-based methods. The nanostructure of the phytantriol dispersions was determined to be cubic phase using SAXS whilst GMO dispersions had a reverse hexagonal nanostructure coexisting with cubic phase. The greatest entrapment of Ova was within phytantriol cubosomes prepared from liquid precursors. Release of Ova from the various formulations was sustained; however, release was significantly faster and the extent of release was greater from fragmented dispersions compared to liquid precursor formulations. Taken together, these results suggest that phytantriol cubosomes can be prepared using liquid precursors and that it is a suitable alternative to GMO. Furthermore, the high entrapment and the slow release of Ova in vitro highlight the potential of phytantriol cubosomes prepared using liquid precursors as a novel vaccine delivery system.     

Development and characterisation of modified poloxamer 407 thermoresponsive depot systems containing cubosomes

The purpose of this study is to develop a thermoresponsive sustained release delivery system combining phytantriol cubosomes and poloxamer 407 (P407). P407 undergoes thermoreversible gelation, where it exists as a free-flowing liquid at low temperature and gels upon heating. However, this polymer has the major draw back of fast erosion in aqueous environments which needs to be addressed. Three different concentrations of P407 (12%, 15% and 17% (w/v)) were formulated with various additives (methyl cellulose (MC), dextran, carrageenan and Pluronic-R (25R4)). The rheological characteristics and in vitro stability were investigated. The sol-gel transition temperature of P407 was lowered in the presence of the phytantriol cubosomes. The addition of MC and dextran did not affect the sol-gel transition temperature whereas 25R4 increased the gelation temperature. No transition was observed for the carrageenan formulations. The presence of 25R4 allowed the development of formulations that were free flowing liquid at working temperature (22 °C), gelled at body temperature (37 °C) and had improved stability in an aqueous environment. Both rheological and in vitro stability studies suggested that cubosome-loaded 17% (w/v) P407 with 25R4 in 1:1 molar ratio may have a potential as sustained release delivery system.     

利巴韦林温度-离子敏感型鼻用原位凝胶喷雾剂的制备及体外性质考察

目的制备具有适宜临界相变温度和临界相变阳离子强度,及适宜的喷雾粒度、使用方便、缓慢释放药物的温度-离子敏感复合型鼻用原位凝胶。方法以临界相变温度、临界相变阳离子强度、喷雾粒度为考察指标筛选温敏及离子敏材料的用量,制备利巴韦林温度-离子敏感复合型原位凝胶。以透析袋法评价该复合凝胶的凝胶外排水量、溶蚀速率、体外释放度,并以断裂距离为指标评价凝胶的黏膜黏附力。结果以质量分数为0.3%的去乙酰化结冷胶和质量分数为18.0%的泊洛沙姆407制备的温度-离子敏感复合型原位凝胶,临界相变温度为32.6℃,临界相变阳离子强度为93.4 mmol.kg-1,喷雾粒度为68.0μm,凝胶外排水质量分数为(13.8±0.8)%,溶蚀速度常数为1×10-4min-1,断裂距离为(1.60±0.06)mm。该混合凝胶具有良好的体外缓释特征。结论该复合型原位凝胶剂适宜作为水溶性药物的鼻用缓释载体。     

D-Optimal Design in the Development of Rheologically Improved In Situ Forming Ophthalmic Gel

In situ forming ophthalmic gels need to be fine tuned considering all the biopharmaceutical challenges of the front of the eye in order to increase drug residence time at the application site resulting in its improved bioavailability and efficacy. The aim of this study was to develop in situ forming ophthalmic poloxamer P407/poloxamer P188/chitosan gel fine tuned in terms of polymer content, temperature of gelation, and viscosity. Minimizing the total polymer content while retaining the advantageous rheological properties has been achieved by means of D-optimal statistical design. The optimal in situ forming gel was selected based on minimal polymer content (P407, P188, and chitosan concentration of 14.2%, 1.7%, and 0.25% w/w, respectively), favorable rheological characteristics, and in vitro resistance to tear dilution. The optimal in situ forming gel was proved to be robust against entrapment of active pharmaceutical ingredients making it a suitable platform for ophthalmic delivery of active pharmaceutical ingredients with diverse physicochemical properties.     

阿昔洛韦壳聚糖眼用温敏性原位凝胶的研制及其体外释药研究

目的 制备阿昔洛韦（ACV）壳聚糖（CS）眼用温敏性原位凝胶（ISG）,并对其体外释药特性进行考察.方法 以CS为增黏剂及吸收促进剂,以泊洛沙姆407和188（P407,P188）为基质,制备ACV-CS-ISG,以胶凝温度为指标,筛选P407与P188的最佳配比;采用无膜溶出模型对ACV-CS-ISG的体外释药特性进行考察.结果 当P407与P188的处方用量分别为21%及6%时,ACV-CS-ISG胶凝温度为（33.6±0.4）℃,人工泪液稀释后变为（34.2±0.3）℃,与人眼表温度（34℃）相似;体外释药及凝胶溶蚀均呈现零级动力学特征,且两者相关性良好.结论 ACV-CS-ISG具有理想的胶凝温度及较好的缓释效果,值得进一步研究.     

Effect of sodium chloride on the release,absorption and safety of diclofenac sodium delivered by poloxamer gel

Poloxamer solutions prepared with poloxamers and sodium chloride were previously reported to undergo a phase transition to bioadhesive gels at body temperature. For the development of a thermosensitive diclofenac sodium-loaded poloxamer gel, here we investigated the effect of sodium chloride on the release, safety and rectal absorption in rats of diclofenac sodium delivered by the poloxamer gels. P 188 delayed the release rates of diclofenac sodium from poloxamer gels. However, sodium chloride showed no significant effect on the release rates of diclofenac sodium from poloxamer gels. Release mechanism analysis showed the release of diclofenac sodium was proportional to the time. The initial plasma concentrations of diclofenac sodium in the rectal formulation [diclofenac sodium/poloxamer 407 (P 407)/poloxamer 188 (P 188)/sodium chloride (2.5/15/17/0.8%)] were significantly higher compared with those in semi-solid suppository. Furthermore, it gave significantly faster Tmax of diclofenac sodium than did semi-solid suppository, indicating that the diclofenac sodium from poloxamer gel could be absorbed faster than that from semi-solid one in rats. It did not cause any morphological damage to the rectal tissues. These results suggested that poloxamer gel with sodium chloride could be a more effective and safe rectal delivery system of diclofenac sodium.     

硝酸毛果芸香碱温敏凝胶的研制及溶蚀性能研究

目的制备硝酸毛果芸香碱温敏凝胶,考察其载药凝胶溶蚀行为。方法以泊洛沙姆为温敏凝胶基质制备硝酸毛果芸香碱眼用凝胶,通过凝胶相变温度筛选最佳处方,采用无膜溶蚀实验研究凝胶释药特性。结果18%、19%、20%的泊洛沙姆407溶液在体温范围内发生相变形成凝胶,其pH≈7,凝胶中硝酸毛果芸香碱释放速度分别为0.462、0.393、0.294 mg.min-1。结论18%-20%泊洛沙姆407溶液适合作为眼部给药的温敏凝胶基质,凝胶中药物释放基本符合零级释放行为。     

眼用盐酸倍他洛尔脂质体-原位凝胶的研制及体外释药的研究

目的制备盐酸倍他洛尔(BH)眼用脂质体-原位凝胶(ISG),并对其体外释药特性进行考察。方法采用逆向蒸发法制备BH脂质体(BHL);以泊洛沙姆407和188(P407,P188)为温敏性ISG基质,以胶凝温度为指标,筛选P407与P188的最佳配比;采用无膜溶出模型对BHL的体外释放行为进行考察。结果 BHL的平均包封率为(88.24±5.46)%(n=3);当P407与P188的处方用量分别为21%及6%时,胶凝温度最接近人眼表温度(34℃);BHL-ISG体外药物释放和凝胶溶蚀均呈现零级释放特征,两者相关性良好。结论 BHL-ISG结合脂质体和原位凝胶的特点,延缓药物释放,为其角膜滞留性研究奠定了基础。     

A new vaginal delivery system of amphotericin B: a dispersion of cationic liposomes in a thermosensitive gel

Amphotericin B (AmB) is used in the treatment of fungal infections; however, its clinical use is limited by its toxic side effects. In this study, AmB-loaded cationic liposome gels were formulated with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), and cholesterol (CH) at a molar ratio of DOPE:DOTAP:CH?=?4:5:1 in thermosensitive gel composed of poloxamer 407 (P407) and poloxamer 188 (P188). To enhance the solubility of AmB, 6 mol% of distearoyl phosphatidyl ethanolamine–polyethylene glycol was added prior to encapsulation of the drug into liposomes. Scanning electron microscopy was used to observe the AmB encapsulated cationic liposome gels. In vitro release, stability and cytotoxicity of AmB in cationic liposome gels were evaluated. The particle size and zeta potential of AmB-loaded liposomes were in the range of 400–500?nm and 40–60 mV, respectively. The thermosensitive gel at the ratio of P407:P188?=?15:15 (w/w) gelled at 37°C, approximating body temperature. Encapsulation efficiency of AmB was ～50–60%, which was influenced by the ratio of AmB to lipid. Moreover, AmB-loaded cationic liposome gels were more stable and less toxic than free AmB. From these results, cationic liposome gel formulations may be useful for vaginal delivery of AmB.     

安乃近原位凝胶的制备及体外评价

目的 制备安乃近原位凝胶,延长安乃近在体内的作用时间.方法 以泊洛沙姆407(P407)和泊洛沙姆188(P188)作为载体材料,采用冷溶法制备安乃近原位凝胶,考察P407和P188的含量、亚硫酸氢钠及安乃近浓度对胶凝温度的影响,并用透析袋法考察凝胶的体外释药情况.结果 当P407浓度为23％、P188浓度为6％、亚硫酸氢钠的浓度为0.2％时,所制得的安乃近原位凝胶注射剂的胶凝温度合适,为35.3℃时,该凝胶在1h内的平均体外累积释放率为40.57％,较安乃近水溶液同时间内的累积释放率低50.39％.结论 安乃近原位凝胶的温敏性明显,其胶凝温度适合体内给药;安乃近原位凝胶对安乃近药物的释放显示出了明显的缓释效应,可以进一步用于临床.     

Chitosan in situ gelation for improved drug loading and retention in poloxamer 407 gels

A method for the in situ gelation of poloxamers and the mucoadhesive polymer chitosan has been developed by exploiting the tendency of poloxamer solution to form gel at physiological temperatures and of chitosan (CT) to form ionotropic gel structures in the presence of sodium tripolyphosphate (TPP). Novel poloxamer gels containing CT-TPP complex formed in situ during the administration were prepared by mixing poloxamer-CT and poloxamer-TPP solutions in double syringes. The micellization and gelation of poloxamer 407 in the presence of chitosan and/or TPP were studied using differential scanning calorimetry and tube inversion; both additives were found to reduce the critical micellization temperature and critical gelation temperature of poloxamer aqueous solution. The poloxamer gels containing CT-TPP complex formed in situ were found to exhibit reduced dissolution rate and superior release characteristics with three different drugs--metoprolol, doxycycline and flufenamic acid. Furthermore, by varying the compositions of the two solutions independently, it is possible to control the pH in a way to suit the solubilization of a drug as well as the specific environment of a particular application site. By varying the concentrations of chitosan, TPP and poloxamer, the delivery system can be fine-tuned to afford gels with specific properties, ranging from nanoparticle suspensions to semisolid gels. These in situ gels have the potential to increase the utility of thermo-reversible poloxamers in drug delivery.     

Poloxamer/Cyclodextrin/Chitosan-Based Thermoreversible Gel for Intranasal Delivery of Fexofenadine Hydrochloride

To enhance permeation and solubility of an intranasal delivery system of fexofenadine hydrochloride (FXD HCl), a new formulation using poloxamer 407 (P407)/hydroxypropyl-β-cyclodextrin (HP-β-CD)-based thermoreversible gels with chitosan, was developed. Prepared gels were characterized by gelation temperature, viscosity, viscoelasticity, and drug release profile. The in vitro permeation study was performed in primary human nasal epithelial cell monolayers cultured by air–liquid interface method. The addition of chitosan caused the slight elevation of gelation temperature and viscosity-enhancing effect. Viscosity enhancement by the incorporation of chitosan caused the retardation of drug release from P407 gels in in vitro release test. The in vitro permeation profile showed that the increase in chitosan content (0.1% and 0.3%, w/v) significantly enhanced the permeation of FXD HCl. After intranasal administration of P407/HP-β-CD–based thermoreversible gels containing 0.1% and 0.3% of chitosan in rabbits at 0.5 mg/kg dose, plasma concentrations of FXD HCl were significantly higher than those of nasal solutions (p < 0.05). In particular, the bioavailability of the optimized thermoreversible gel containing 0.3% chitosan was about 18-fold higher than that of the solution type. These results suggested the feasibility that thermosensitive gels could be used as an effective dosage form to enhance the nasal absorption of FXD HCl.     

丙烯酸-泊洛沙姆407共聚物的合成及其原位胶凝性质

目的制备丙烯酸和泊洛沙姆407构成的共聚物,研究其温度敏感的原位胶凝性质。方法将泊洛沙姆407溶于丙烯酸单体,引发聚合反应,产物用红外光谱和凝胶渗透色谱表征。用旋转黏度计测定共聚物水溶液的黏度随温度的变化。以维生素B12为模型药物,研究药物的释放性质。结果较低浓度的丙烯酸泊洛沙姆407共聚物水溶液具有受热原位胶凝的性质,其胶凝特征与共聚物的组成、浓度、溶液pH等有关,共聚物凝胶可延缓药物释放。结论丙烯酸泊洛沙姆407共聚物可望应用于黏膜给药的原位凝胶递药系统。     

吡嘧司特钾眼用原位温度敏感凝胶的制备及其体外释放度的研究

目的：以吡嘧司特钾为模型药物,制备眼用原位温度敏感凝胶,考察其体外释放度。方法：以泊洛沙姆407/188为基质,筛选最佳处方以达到合适的胶凝温度,建立高效液相色谱法测定吡嘧司特钾含量并以无膜溶出模型考察体外释放度。结果：处方中以5%甘露醇为溶媒,0.1%吡嘧司特钾（w/v）、0.01%苯扎溴铵（v/v）、6%泊洛沙姆188（w/v）和20%泊洛沙姆407（w/v）的组成可以达到最适胶凝温度,经影响因素试验考察证明该制剂性质稳定,体外释放度考察结果表明药物的释放与时间成线性关系。结论：本文制备的吡嘧司特钾眼用原位温度敏感凝胶具有很好的温度敏感性,能够延长药物在眼部停留时间且给药方便,有望开发成为一种新型眼用给药制剂。     

注射用粉防己碱温敏型缓释原位凝胶的制备

目的 制备以泊洛沙姆407(P407)为基本材料的注射用粉防己碱温敏型缓释原位凝胶,并考察其体外溶出行为.方法 采用冷溶法制备凝胶,以胶凝温度为指标,考察单独使用P407和加入其他辅料F188、PEG1500、HPMC、MC对胶凝温度的影响;采用无膜溶出法考察凝胶的体外溶蚀和释放行为,并采用HPLC测定溶出液中药物的含量,筛选较优处方.结果 胶凝温度随P407浓度的增大而降低;且当P407浓度低于15％时不发生相转变,辅料F188、PEG1500、MC的加入不能制备出符合要求的凝胶;8.0％、8.5％ 、9.0％ HPMC分别与8.0％ P407 混昆合制备凝胶的胶凝温度符合要求;HPMC浓度越高,药物释放越快,8.0％ HPMC和8.0％ P407混合后,胶凝温度和缓释效果均符合实验要求.结论 筛选出的处方中大大降低了P407的浓度,同时胶凝温度和缓释效果均符合实验要求,该温敏性凝胶具有良好的温度敏感性,制备方法简单可行.     

Cubosome Dispersions as Delivery Systems for Percutaneous Administration of Indomethacin

Purpose The present study concerns the production and characterization of monooleine (MO) dispersions as drug delivery systems for indomethacin, taken as model anti-inflammatory drug. Methods Dispersions were produced by emulsification and homogenization of MO and poloxamer in water. Morphology and dimensional distribution of the disperse phase have been characterized by cryo-transmission electron microscopy and photon correlation spectroscopy, respectively. X-ray diffraction has been performed to determine the structural organization of the disperse phase. Sedimentation field flow fractionation (SdFFF) has been performed to investigate drug distribution in the dispersion. An in vitro diffusion study was conducted by Franz cell associated to stratum corneum epidermis membrane on cubosome dispersions viscosized by carbomer. In vivo studies based on skin reflectance spectrophotometry and tape stripping were performed to better investigate the performance of cubosome as indomethacin delivery system. Results Microscopy studies showed the coexistence of vesicles and cubosomes. X-ray diffraction revealed the presence of a bicontinuous cubic phase of spatial symmetry Im3m (Q²²⁹). SdFFF demonstrated that no free drug was present in the dispersion. Indomethacin incorporated in viscosized MO dispersions exhibited a lower flux with respect to the analogous formulation containing the free drug in the aqueous phase and to the control formulation based on carbomer gel. Reflectance spectroscopy demonstrated that indomethacin incorporated into MO dispersions can be released in a prolonged fashion. Tape-stripping experiments corroborated this finding. Conclusions MO dispersions can be proposed as nanoparticulate systems able to control the percutaneous absorption of indomethacin.     

Release of flurbiprofen from poloxamer 407 gel

Release rates of flurbiprofen from transdemal gels made of poloxamer 407 were evaluated using a membraneless diffusion cell in order to study the effects of formulation variables on flurbiprofen release such as poloxamer 407 (17.5–25%), drug (0.1–1.0%), ethanol (10–20%), PG or PEG 300 (5–15%) concentrations and gel pH (3–7). Isopropyl myristate was employed as a receptor medium for the drug released from the gel. The diffusion coefficient of flurbiprofen decreased linearly as the amount of poloxamer 407 and the drug in the gel increased. The release rate of flurbiprofen was gel pH-dependent and the diffusion coefficient of the drug in the gel increased as the pH of the gel increased. The addition of more ethanol in the gel increased the drug release, resulting from the increase of the thermodynamic activity of the drug in the aqueous phase of the gel. However, the concentration effects of PG and PEG 300 on the release rate of flurbiprofen were negligible over the concentration range used.     

Intratumoral administration of paclitaxel in an in situ gelling poloxamer 407 formulation

In order to examine the efficacy of paclitaxel (Taxol, Bristol-Myers Squibb) after administration locally at the tumor site, we have developed a thermo-reversible gelling formulation in poloxamer 407 (Pluronic F-127) solution. Paclitaxel was incorporated in poloxamer 407 [20% (w/w)] at 0.5- and 1.0-mg/mL concentrations. The in vitro release studies were carried out in phosphate-buffered saline (pH 7.4) at 37 degrees C. Control and paclitaxel-poloxamer 407 formulations were administered intratumorally at a dose of 20 mg/kg in B16F1 melanoma-bearing mice. The change in tumor volume as a function of time and the survival of treated animals were used as measures of efficacy. Poloxamer 407 solution undergoes a reversible sol-gel transition when the temperature is raised to above 21 degrees C. In vitro paclitaxel release from poloxamer 407 gels was very slow (only 6.1% after 6 hr) probably due to the poor aqueous solubility of the drug. Significant enhancement in the anti-tumor efficacy was noted following intratumoral administration of paclitaxel-poloxamer 407 formulation. The initial tumor growth rate was delayed by 67% and the tumor volume doubling time was increased by 72% relative to saline control. In addition, more than 91% of the tumor-bearing animals that received paclitaxel in poloxamer 407 gel survived on day 15 post-administration as compared to 58% in the control group. The results of this study show significant benefit of paclitaxel for solid tumor when administered locally in an in situ gelling poloxamer 407 formulation.     

Influence of magnesium aluminium silicate on rheological, release and permeation characteristics of diclofenac sodium aqueous gels in-vitro

The effect of magnesium aluminium silicate (MAS) on rheological, release and permeation characteristics of diclofenac sodium (DS) aqueous gels was investigated. DS aqueous gels were prepared using various gelling agents, such as 15% w/w poloxamer 407 (PM407), 1% w/w hydroxypropylmethylcellulose (HPMC), and 1% w/w high and low viscosity grades of sodium alginate (HV-SA and LV-SA, respectively). Different amounts of MAS (0.5, 1.0 and 1.5% w/w) were incorporated into the DS gels. Incorporation of MAS into the DS gels prepared using SA or PM407 caused a statistical increase in viscosity (P<0.05) and a shift from Newtonian flow to pseudoplastic flow with thixotropic property. The DS release rates of these composite gels were significantly decreased (P<0.05) when compared with the control gels. This was due to an interaction between MAS and PM407 or SA, and adsorption of DS onto MAS particles. Moreover, a longer lag time and no change in DS permeation flux were found when MAS was added to the gels. The findings suggest that the rheological characteristics of gels prepared using PM407 or SA could be improved by incorporating MAS. However, the use of MAS could retard the DS release and extend the lag time of DS permeation.