A modern approach for controlled transdermal delivery of diflunisal: optimization and in vivo evaluation

The purpose of the present work was to elaborate an optimized transdermal therapeutic system for diflunisal. Selection of suitable ingredients was done via solubility and phase behavior studies. Composition of microemulsion (ME) systems consisting of butyl lactate, Brij^® 97, Transcutol^® and water was optimized using augmented simplex lattice mixture design. The independent variables selected were the percentages of butyl lactate, surfactant mixture and water. The dependent variables were refractive index, pH, conductivity, viscosity, drug solubility in the ME formulation and the ex vivo skin permeation flux. Mathematical equations and response surface plots were used to relate the dependent and independent variables. The statistical validity of the polynomials was established. Optimized formulation factors were selected by desirability approach. The optimized ME formulation was converted into gel using Carbomer^® 934. The microemulsion based gel (MBG) showed better spreadability and 5.07-fold increase in the transdermal flux than Carbomer^® 934 gel. The in vivo antihyperalgesia assay performed on mice showed significant reduction of the licking time in the treated group compared to the control group. This demonstrated the reliability of the simplex lattice statistical design for predicting optimum ME formulation. The developed MBG proved its in vivo efficiency for transdermal delivery of diflunisal.     

Microemulsions as a Surrogate Carrier for Dermal Drug Delivery

Microemulsions are isotropic, thermodynamically stable transparent (or translucent) systems of oil, water, and surfactant, frequently in combination with a cosurfactant with a droplet size usually in the range of 20–200 nm. Since their discovery, they have attained increasing significance both in basic research and in industry. Due to their distinct advantages such as enhanced drug solubility, thermodynamic stability, facile preparation, and low cost, uses and applications of microemulsions have been numerous. Recently, there is a surge in the exploration of microemulsion for transdermal drug delivery for their ability to incorporate both hydrophilic (5-fluorouracil, apomorphine hydrochloride, diphenhydramine hydrochloride, tetracaine hydrochloride, and methotrexate) and lipophilic drugs (estradiol, finasteride, ketoprofen, meloxicam, felodipine, and triptolide) and enhance their permeation. Very low surface tension in conjunction with enormous increase in the interfacial area due to nanosized droplets of the microemulsion influences the drug permeation across the skin. A large number of oils and surfactants are available, which can be used as components of microemulsion systems for transdermal delivery but their toxicity, irritation potential, and unclear mechanism of action limit their use. Besides surfactants, oils can also act as penetration enhancers (oleic acid, linoleic acid, isopropyl myristate, isopropyl palmitate, etc.). The transdermal drug delivery potential of microemulsions is dependent not only on the applied constituents of the vehicle but also drastically on the composition/internal structure of the phases which may promote or hamper the drug distribution in the vehicles. This article explores microemulsion as transdermal drug delivery vehicles with emphasis on components selection for enhanced drug permeation and skin tolerability of these systems and further future directions.     

微乳液对碘绿增溶性能的影响

通过分光光度法测定了pH值为5.4时,CTMAB/正丁醇/正庚烷/水、OP-10/正丁醇/正庚烷/水、SDS/正丁醇/正庚烷/水O/W型微乳液介质中,碘绿的分配系数和平均有效介电常数。结果表明,碘绿的分配系数规律为CTMAB阳离子微乳液>SDS阴离子微乳液>OP-10非离子微乳液。平均有效介电常数规律为OP-10非离子型>CTMAB阳离子型>SDS阴离子型。并初步解释了微乳液类型对碘绿增溶能力和增溶位置的影响。     

PEO—PPO—PEO包裹AuZnO纳米粒子的制备

采用一罐纳米乳液法,以三嵌段共聚物PEO—PPO—PEO为表面活性剂,1,2-十六烷二醇为还原剂,乙酰丙酮锌和醋酸金为前驱体,成功合成了AuZnO纳米粒子,TEM测试和X-射线衍射仪（XRD）测试得出该纳米粒子以球形为主,粒径约为10nm,粒度分布均匀,分散性好,结晶性能好,在紫外照射下,AuZnO纳米粒子能有效降解有色染料罗丹明B。该多功能AuZnO纳米粒子有望在催化材料、光电和生物医药等方面发挥有益作用。     

In vitro and in vivo antifungal activity of a water-dilutable cassia oil microemulsion against Geotrichum citri-aurantii

BACKGROUND: Recently, food‐grade microemulsions have been of increasing interest to researchers and have shown great potential in industrial applications. In this study a food‐grade water‐dilutable microemulsion system with cassia oil as oil, ethanol as cosurfactant, Tween 20 as surfactant and water was developed and its antifungal activity in vitro and in vivo against Geotrichum citri‐aurantii was assessed. RESULTS: The phase diagram results confirmed the feasibility of forming a water‐dilutable microemulsion based on cassia oil. One microemulsion formulation, cassia oil/ethanol/Tween 20 = 1:3:6 (w/w/w), was selected with the capability to undergo full dilution with water. The average particle size was 6.3 nm. The in vitro antifungal experiments showed that the microemulsion inhibited fungal growth on solid medium and prevented arthroconidium germination in liquid medium and that cassia oil had stronger activity when encapsulated in the microemulsion. The in vivo antifungal experiments indicated that the water‐dilutable microemulsion was effective in preventing postharvest diseases of citrus fruits caused by G. citri‐aurantii. CONCLUSION: The results of this study suggest a promising utilisation of water‐dilutable microemulsions based on essential oils for the control of postharvest diseases. Copyright © 2012 Society of Chemical Industry     

Inverse microemulsion copolymerization of butyl acrylate and acrylamide: kinetics,colloidal parameters and some model applications

The inverse microemulsion copolymerization of acrylamide and butyl acrylate initiated by ammonium peroxodisulphate, a water‐soluble initiator, and stabilized by anionic emulsifiers sodium bis‐2‐ethylhexylsulfosuccinate and sodium dodecylsulphate (SDS) has been studied. An increase of SDS concentration was observed to increase both the rate of polymerization and the particle size. The average number of radicals per particle (n?) is much below 0.5, which indicates desorption of monomeric radicals from polymer particles. The exit (desorption) rate constants k′_des (cm² s^?1) and k_des (s^?1) were evaluated as a function of SDS concentration (or the particle size) according to the Ugelstad/O'Toole (I), Nomura (II) and Gilbert (III) models. The value of k_des (s^?1) decreases with increasing particle size (or SDS concentration) for all three (I, II and III) models. A complex trend appears for k′_des (cm² s^?1): the Ugelstad/O'Toole model estimates a decrease, the Nomura model finds no variation and the Gilbert model estimates even a slight increase in k′_des with increasing SDS concentration. Copyright © 2006 Society of Chemical Industry     

Characterization of cobalt oxide nanocatalysts prepared by microemulsion with different surfactants, reduction by hydrazine and mechanochemical method

Cobalt oxide (Co₃O₄) nanoparticles were prepared by different techniques (i) by microemulsion with different surfactants, (ii) by reduction as nanometal with hydrazine hydrates and (iii) by thermal treatment of precursor obtained from mechanochemical reaction of Co(NO₃)·H₂O with NH₄HCO₃. The products were calcined at 400 °C to give crystalline Co₃O₄. The obtained different samples of Co₃O₄ were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM) from which the particle size was calculated. The results revealed that all samples obtained from different methods were nanosized particles.     

紫外光聚合法合成有机硅改性苯丙微乳液

以丙烯酸丁酯和苯乙烯为单体、γ-甲基丙烯酰氧丙基三甲氧基硅烷为偶联剂和交联剂、十二烷基硫酸钠为表面活性剂、正戊醇为助表面活性剂、米氏酮和二苯甲酮为光引发剂,采用紫外光聚合法在室温下合成有机硅改性苯丙微乳液;考察了该微乳液的耐酸碱性能;采用傅里叶变换红外光谱、热重分析、透射电子显微镜、紫外-可见分光光度计等方法对该微乳液及其涂膜的结构、形貌、光学和热学性能进行了表征。实验结果表明,有机硅改性苯丙微乳液的耐酸性好于耐碱性;该微乳液为透明或半透明状,单体含量为20g(在100g水中)的微乳液在550nm处的透光率达55%,在760nm处的透光率可达87%;粒径为34～55nm,粒径分布指数为1.16～1.18。表征结果显示,所合成的产物为有机硅改性的苯乙烯与丙烯酸丁酯的共聚物。     

Gemini微乳液的制备与微相结构研究

采用Gemini表面活性剂C_(12)-3-C_(12_)2Br与水、正辛烷和正丁醇制备了不同相结构的微乳液,绘制了拟三元相图,并通过电导法、偏光显微镜以及荧光探针法研究了Gemini微乳液体系的相结构与相行为。结果表明:与常规表面活性剂相比,采用Gemini表面活性剂可在较低浓度下形成微乳液,微乳液中依然存在油包水、双连续相结构及水包油等微相结构。微乳液中存在油丝液晶织构,而Gemini表面活性剂的独特分子结构使微乳液中层状液晶结构更易生成。认为微乳液体系所处的多变微观环境是导致不同微相结构微乳液的微极性存在差异的主要原因。     

汽油微乳液的制备与性能研究

探讨了汽油微乳体系中，不同乳化方式、表面活性剂的配比、助表面活性剂对掺水量和稳定性的影响；并对制得的微乳汽油进行性能测试。研究结果表明：当助表面活性剂与阳离子表面活性剂的质量比为2时，制得的微乳汽油中掺水量最适宜燃烧；阴阳离子表面活性剂质量比为9：1复配作乳化剂时，不用助表面活性剂也易制得稳定的微乳汽油；上述微乳汽油的电导率、粘度符合燃油标准；稳定性在10～40℃，可存在一年以上。该微乳汽油具有节能、环保作用。