Sustainable Stabilizer-Free Nanoparticle Formulations of Valsartan Using Eudragit® RLPO

The bioavailability of the antihypertensive drug valsartan can be enhanced by various microencapsulation methods. In the present investigation, valsartan-loaded polymeric nanoparticles were manufactured from Eudragit^® RLPO using an emulsion–solvent evaporation method. Polyvinyl alcohol (PVA) was found to be a suitable stabilizer for the nanoparticles, resulting in a monodisperse colloid system ranging in size between 148 nm and 162 nm. Additionally, a high encapsulation efficiency (96.4%) was observed. However, due to the quaternary ammonium groups of Eudragit^® RLPO, the stabilization of the dispersion could be achieved in the absence of PVA as well. The nanoparticles were reduced in size (by 22%) and exhibited similar encapsulation efficiencies (96.4%). This more cost-effective and sustainable production method reduces the use of excipients and their expected emission into the environment. The drug release from valsartan-loaded nanoparticles was evaluated in a two-stage biorelevant dissolution set-up, leading to the rapid dissolution of valsartan in a simulated intestinal medium. In silico simulations using a model validated previously indicate a potential dose reduction of 60–70% compared to existing drug products. This further reduces the expected emission of the ecotoxic compound into the environment.     

W/O/W复相乳液法合成多元氮丙啶/聚酯微胶囊的研究及表征

通过W/O/W型复相乳液法合成制备多元氮丙啶(XAMA-7)/聚酯交联控制型微胶囊,对合成过程及工艺参数的影响进行了研究,研究发现:溶剂蒸发速率太高会导致微胶囊表面皱缩和多孔,溶剂在2小时蒸发完全时得到的微胶囊表面硬化速率均匀;低表面自由能的聚酯对形成微胶囊有利,其值为34.5 mJ/m~2时可以制得完整包覆的微胶囊;胶体稳定剂用量为2.5%时可以得到具有中空结构的规整球形微胶囊;壁心质量比对所制备的微胶囊形态和囊心含量具有重要的影响,壁心质量比为50%:50%的微胶囊球形规整且壁厚均匀,囊心含量约为22%;通过扫描电镜和红外光谱对微胶囊形貌和组成进行表征,结果证明微胶囊呈中空结构且壁厚均匀,聚酯对多元氮丙啶(XAMA-7)形成包覆,XAMA-7分布于微胶囊的中心区域。     

Compatibility between Drugs and Polymer in Nanoparticles Produced by the Miniemulsion-Solvent Evaporation Technique

Encapsulation of poorly soluble drugs in polymer nanoparticles is a common strategy to increase bioavailability of drugs. The miniemulsion-solvent evaporation technique is widely used for encapsulating drugs in polymer nanoparticles because it is a versatile process, allowing many drug–polymer pair combinations. However, above a critical concentration of drug, which depends on the drug and polymer, nanoparticles tend to precipitate. Herein, the importance of drug solubility and miscibility in the polymer phase for selecting the optimal polymer matrix is investigated. Ibuprofen, naproxen methyl ester, and naproxen, as models for poorly soluble drugs, are encapsulated with various loadings in polycaprolactone nanoparticles by the miniemulsion-solvent evaporation method. The miscibility between drug and polymer is estimated by calculating Flory–Huggins interaction parameters (χ) from differential scanning calorimetry measurements and calculating the difference in Hansen solubility parameter of drugs and polymer. Both values can be used for determining the feasibility of the drug encapsulation in polymer nanoparticles.     

膜乳化法与复乳法结合制备粒径均一的载溶菌酶微胶囊

采用微孔膜乳化法与复乳法结合制备粒径均一可控的以聚乳酸和聚(乳酸-羟基乙酸)共聚物为膜材的载溶菌酶微胶囊,粒径分布系数CV(Coefficient of Variation)为14.04%,远低于机械搅拌法制备的微囊的CV(76.54%). 分别加入内水相添加剂PVA, PEG400, HP-b-CD,使溶菌酶的包埋率从无添加剂时的68.1%分别增大到86.6%, 89.0%和94.1%. 添加剂降低了溶菌酶的突释. PEG400, PEG6000, HP-b-CD的加入降低了溶菌酶的释放速率,而PVP或PVA的加入则加快了溶菌酶的释放. 溶菌酶在油水界面上的吸附变性是失活的主要原因. 在酶液中加入PEG400, PEG6000, PVP, HP-b-CD可有效地避免由于油水界面造成的溶菌酶活性的损失.     

一种水溶性囊芯微胶囊的制备方法

以水为囊芯,以聚对苯二甲酸二乙酯（PET）为囊壁,采用乳液-溶剂蒸发法合成一种水溶性囊芯的微胶囊,微胶囊表面光滑,粒径分布窄,平均粒径约100μm。采用扫描电子显微镜（SEM）和光学显微镜（OM）表征微胶囊的表面形貌特征,粒径及其分布。实验结果表明,乳化剂浓度和芯／壁比例等对PET微胶囊大小和粒径分布有较大影响。     

乳化-溶剂挥发法制备聚乳酸载药微球

采用o/w型乳化-溶剂挥发法来制备载药微球,以二氯甲烷为溶剂相,以聚乳酸为载体材料,以维A酸为包埋药物,以吐温-80和明胶为乳化剂。探索载药微球制备过程中的变量(高剪切转速、高剪切时间、内外相体积比、壁材用量等)对载药微球粒径大小、包封率以及稳定性等的影响。得出最优载药微球制备方案:明胶浓度7.5mg/mL,吐温浓度6mg/mL,聚乳酸浓度10 mg/mL,内外相体积比1∶10,剪切时间30min,搅拌速度300r/min,挥发时间3h。所制得的聚乳酸载药微球形态光滑且分散性较好,包封率为52.42%。     

W／O／W复乳溶剂蒸发法制备微胶囊的影响因素及研究新进展

重点综述了W/O/W复乳溶剂蒸发法制备微胶囊的过程及影响因素,并结合SPG膜乳化法阐述了其最新研究进展.     

双氯芬酸钠缓释微胶囊的制备与表征

以乙基纤维素为壁材,采用乳化-溶剂扩散技术制备双氯芬酸钠缓释微胶囊,通过考察包封率和载药量确定其制备工艺,并对微胶囊的形态和释放度等理化性能进行表征．结果表明,当有机相中乙基纤维素的质量浓度为3×10^-2g／mL,水相中乳化剂十二烷基硫酸钠的质量浓度为3×10^-3g／mL,双氯芬酸钠与乙基纤维素的投料比mEC：mDs为1：1,搅拌速度900r／min时制备出的微胶囊形态圆整,粒径范围6～24gm,药物包封率达25．12％,在人工肠液中可平稳缓释达8h．     

Synthesis and characterization of polyfunctional aziridine/polyester microcapsules by multiple emulsion-solvent evaporation method

Polyfunctional aziridine/polyester microcapsules as control-release waterborne cross-linker were synthesized by multiple emulsion-solvent evaporation method. The results show that, a lower surface free energy with shell polyester is more favourable for the formation of microcapsules. Full encapsulating microcapsules are synthesized with the polyester with a surface free energy of 34.5 mJ/m². Shell-to-core feeding mass ratio has a significant influence on the morphology and core content of the resulting microcapsules. Well defined spherical microcapsules with uniform shell thickness and core content at around 22% are produced at a shell-to-core mass ratio of 1:1. When 2.5% of colloid stabilizer is used, hollow spherical microcapsules are obtained. A high solvent evaporation rate results in wrinkling and porosity of the microcapsules, and an evaporation rate equivalent to solvent elimination in about 2 h provides a uniform rate of surface hardening. The characterization of the microcapsules by SEM and FTIR demonstrates that polyfunctional aziridine is encapsulated at the centre of the microcapsule. The microcapsules synthesized can be broken at a high shear rate.