An overview on in situ micronization technique – An emerging novel concept in advanced drug delivery

The use of drug powders containing micronized drug particles has been increasing in several pharmaceutical dosage forms to overcome the dissolution and bioavailability problems. Most of the newly developed drugs are poorly water soluble which limits dissolution rate and bioavailability. The dissolution rate can be enhanced by micronization of the drug particles. The properties of the micronized drug substance such as particle size, size distribution, shape, surface properties, and agglomeration behaviour and powder flow are affected by the type of micronization technique used. Mechanical communition, spray drying and supercritical fluid (SCF) technology are the most commonly employed techniques for production of micronized drug particles but the characteristics of the resulting drug product cannot be controlled using these techniques. Hence, a newer technique called in situ micronization is developed in order to overcome the limitations associated with the other techniques. This review summarizes the existing knowledge on in situ micronization techniques. The properties of the resulting drug substance obtained by in situ micronization were also compared.     

Physicochemical and functional properties of micronized jincheng orange by-products (Citrus sinensis Osbeck) dietary fiber and its application as a fat replacer in yogurt

Orange by-products from juice extraction are generally discarded or used in animal feed due to their low market value. However, orange by-products show potential as dietary fiber (DF) and fat replacers in products such as yogurt. This study assessed the benefits of using orange by-products in DF-enriched materials such as DF powders (OP) and micronized DF with ball-milling (MDF). The study also investigated the effects of adding different levels of OP and MDF on the quality of low-fat yogurt. Results show that MDF showed better physicochemical and functional properties than OP, and that 2% MDF as a fat replacer in yogurt retained most of the textural and sensory properties of full-fat yogurt. Therefore, this study showed that MDF is a promising alternative as a fat replacer in low-fat yogurt, without sacrificing good taste and other qualities of full-fat yogurt.     

改善口服固体制剂溶出度的方法

溶出度是口服固体制剂的质量指标之一,用以保证药物吸收及生物利用度。改善溶出度主要依靠提高崩解度或释放度,药物微粉化或分布于载体以增加表面积及采用其它增溶措施。可选择适当的崩解剂、助溶或增溶性添加剂,改进混合、制粒等工艺和采用载体分散体系,通过器械粉碎或微粉化、微晶化处理以及采用喷雾干燥、冷冻干燥等。     

尼莫地平微粉化物双层渗透泵控释片的制备

目的 制备尼莫地平微粉化物双层渗透泵控释片。方法 以尼莫地平为模型药物,将微粉化增溶技术应用于控释双层渗透泵剂型中,设计并制备体外控释12 h的尼莫地平双层渗透泵片,采用相似因子法（f₂）对不同处方释药行为的相似性进行评价,并对处方进行优化。结果 成功制备了尼莫地平微粉化物双层渗透泵控释片,零级释放特征明显,符合渗透泵的释药机制。结论 将微粉化增溶技术与控释双层渗透泵技术相结合,显著提高了难溶性药物尼莫地平的体外释放,成功制备了控释制剂。     

当归微粉的特征及对阿魏酸溶出的影响

目的:比较当归普通粉和微粉的粉体学特征、水溶性及醇溶性浸出物含量、指标成分阿魏酸溶出量,探索微粉化技术在当归中的应用价值.方法:通过激光粒度分析仪对普通粉和微粉进行表征,扫描电镜(SEM)观察普通粉和细粉的表面形态,测定粉体学参数休止角和堆密度,冷浸法测定水溶性及热浸法测定醇溶性溶出物的含量,利用超声提取进行水溶性指标成分阿魏酸的溶出实验,采用HPLC测定阿魏酸的含量.结果:当归普通粉和微粉的粉体学特征及表面形态差异显著,但水溶性及醇溶性浸出物量、水溶性指标成分阿魏酸的溶出差别不大.结论:微粉化应用于当归,通过对粉体学特征的影响而影响其制剂学性质,但不能显著提高其醇溶性及水溶性浸出物和指标成分阿魏酸的溶出量,生产中不宜对当归进行微粉化.     

非诺贝特体外溶出度考察及其微粉化制剂的研究

目的考察不同厂家非诺贝特固体制剂体外溶出度以及微粉化对非诺贝特溶出度的影响。方法分别以 40 % (φ)乙醇溶液、5 0 % (φ)乙醇溶液、5g/L十二烷基硫酸钠溶液、1 0g/L十二烷基硫酸钠溶液为溶出介质 ,对 4种市售非诺贝特固体制剂的体外溶出度进行考察。采用球磨机制备微粉化非诺贝特 ,对其溶出度进行测定。结果 1 0 g/L十二烷基硫酸钠溶液中微粉化制剂的溶出速率明显快于其余 3种非微粉化制剂 ,初步探讨了非诺贝特固体制剂体外溶出度标准。用相似因子法对自制微粉化胶囊和法国生产的微粉化胶囊的溶出实验数据进行统计分析 ,结果表明两者溶出行为相似 ,相似因子f2 =72 4(5 0≤f2 ≤ 1 0 0 )。结论不同厂家非诺贝特固体制剂的溶出度差异较大 ,微粉化工艺能显著提高非诺贝特的溶出度     

增加难溶性药物溶解度方法新进展

如何增加难溶性药物溶解度是药剂学设计的重点。现就近年来微粉化技术、环糊精包含技术、固体分散技术等传统技术和其它一些新方法对增加难溶性药物溶解度的新进展作一综述。     

Dissolution Rate Enhancement by in Situ Micronization of Poorly Water-Soluble Drugs

Purpose. The purpose of this study was to evaluate a novel in situ micronization method avoiding any milling techniques to produce nano- or microsized drug particles by controlled crystallization to enhance the dissolution rate of poorly water-soluble drugs. Methods. Ibuprofen, itraconazole, and ketoconazole microcrystals were prepared by the association of the previously molecularly dispersed drug using a rapid solvent change process. The drug was precipitated in the presence of stabilizing agents, such as hydrocolloids. The obtained dispersion was spray-dried. Particle size, morphology, dissolution rate, specific surface area, and wettability were analyzed. Physicochemical properties were characterized using differential scanning calorimetry and X-ray diffractometry. Results. The obtained dispersions showed a homogeneous particle size distribution. Drugs are obtained in a mean particle size of approximately 2 m and below. A high specific surface area was created and in situ stabilized. Different stabilizers showed differences in protecting the precipitated drug from crystal growth. The surface was hydrophilized because of the adsorbed stabilizer. Thus, a drug powder with markedly enhanced dissolution rate was obtained. Conclusions. In situ micronization is a suitable method for the production of micro-sized drugs. This technique can be performed continuously or discontinuously and uses only common technical equipment. Compared to milled products drug properties are optimized as all particle surfaces are naturally grown, the particle size is more uniformly distributed and the powder is less cohesive.     

Increase in the Specific Surface Area of Budesonide During Storage Postmicronization

Purpose. To evaluate an anomalous increase in the specific surface area of budesonide during storage postmicronization. Methods. Budesonide was micronized using a conventional air-jet mill. Surface areas and total pore volumes were measured using nitrogen sorption. Porosity was measured using mercury intrusion porosimetry. Particle size was measured using laser diffraction. Results. Budesonide exhibited a surface area increase of 22 ± 2% when stored at 25°C following micronization. The rate of surface area increase was lower at 20°C, suggesting a temperature-dependent stress relaxation mechanism for the micronized particles. The increase in surface area was accompanied by: (a) an increase in total pore volume; (b) a shift of the pore size distribution to smaller pore sizes; (c) a decrease in size of particles above 1 m; and (d) an increase in rugosity/surface roughness. Conclusions. Freshly micronized budesonide exhibited an unusual and significant postmicronization increase in specific surface area upon storage under ambient conditions. Postmicronization stress-relief by intraparticle crack formation, crack propagation with time, and particle fracture seems to be the primary mechanism behind this surface area increase.     

喜树碱微粉的制备工艺、溶出及生物利用度特征研究

目的对难溶性药物喜树碱(camptothecin)进行微粉化研究。方法借助乳化机和高压均质机采用乳化法制备喜树碱微粉,单因素法优化制备工艺。将最优乳化条件下得到的喜树碱微粉(camptothecin micronized powder)进行溶出和生物利用度研究。结果最佳制备工艺条件为聚山梨酯-80用量为0.4%,喜树碱在三氯甲烷-甲醇(8∶2)混合溶剂中的质量浓度为1 mg/m L,水相和油相体积比为7∶3,匀浆速率为7 000 r/min;匀浆时间为11 min。最佳工艺条件下得到的喜树碱微粉水中复溶后的粒径为(165.6±5.3)nm。扫描电镜结果显示喜树碱微粉呈现规则的长条状,颗粒大小比较均匀。溶出研究结果表明喜树碱微粉溶解度和溶出速率比原粉分别提高了1.36倍和4.09倍。口服生物利用度结果表明,与原料药相比,微粉化的喜树碱在大鼠体内的相对生物利用度提高了2.10倍。GC检测结果表明,喜树碱微粉溶剂残留符合ICH标准。结论乳化法制备喜树碱微粉后,改善了喜树碱原粉的溶解度和溶出速率,口服生物利用度得到提高。