两性霉素B脂质体粒度测定方法研究

目的：建立两性霉素B脂质体粒度检测方法，通过测定一组性质不同的样品，找出最佳测定方法。方法：用计算机的图像一数字处理技术结合扫描电镜、透射电镜和激光光散射粒度测定仪分别测定两性霉素B脂质体的粒度。结果：电镜法测定两性霉素B脂质体的粒度为20—100nln，平均粒径为55—75nm；激光光散射法测定两性霉素B脂质体的粒度为30—200nm，平均粒径为50—180nm。结论：激光光散射法能较好反映两性霉素B脂质体在使用时的真实粒度，且方法快速、简便，是一种较好的两性霉素B脂质体粒度测定方法。     

丙泊酚注射液乳粒粒径测定方法探讨

目的：对乳粒粒径测定的方法及仪器参数的设置进行初步探讨。方法：采用经典光散射法,使用马尔文激光散射粒度测定仪分别对仪器的3个参数（遮光度、吸收率、折射率）的设置范围进行考察;以丙泊酚注射液为模型药物,用动态光散射法与经典光散射法测定相同的13批样品,比较平均粒径及小于0．4pm粒子的百分比这2项指标测定结果的差异。结果：马尔文公司的激光粒度测定仪参数设置范围为遮光度5％～10％、吸收率0～0．01、折射率1．47～1．52时对粒径测定结果影响不大;与经典光散射法测得的结果比较,动态光散射法测得的平均粒径较小,测得的小于0．4um的粒子的百分比更大;确立丙泊酚注射液乳粒测定方法为经典光散射法。结论：本试验建立的粒径测定方法及仪器参数可用于不同厂家丙泊酚注射液的粒径测定,使各厂家产品质量具有可比性;本方法的建立为其他类似品种注射剂的粒径测定提供了研究方向及恩路。     

两性霉素B脂质体的制备及药动学

目的:制备两性霉素B脂质体并对其药动学进行研究。方法:采用有机溶剂注入法制备两性霉素B脂质体,用微射流进行整粒,用动态光散射法测定粒径,采用Ultrafree-CL离心超滤管分离游离两性霉素B(F-AMB)与复合两性霉素B(L-AMB)检测包封率,用Wistar大鼠进行药动学研究。结果:两性霉素B脂质体平均粒径为(115±20)nm;包封率>99.9%;大鼠静脉注射,实验药与Amphotec的Cmax,AUC0~168 h和AUC0~∞无显著性差异(P>0.05)。结论:采用有机溶剂注入法制备两性霉素B脂质体具有较高包封率,在大鼠体内的药动学特征与Amphotec一致。     

Determination of the particle size of realgar nano-particles by scanning 

目的：建立纳米雄黄的粒度分析研究方法。方法：利用扫描电镜对纳米雄黄表观形态进行直接观察测定,用激光光散射法对纳米雄黄的粒度分布范围进行分析测定。结果：经扫描电镜和激光光散射颗粒度测定仪的测量,粒径在100 nm以下的纳米雄黄约达90%,其中较大颗粒又是由粒径在5~30 nm左右的细小晶粒和其周围的非晶体聚集而成。结论：扫描电镜法和激光光散射法快速、简便、准确,可用于纳米雄黄的粒度检测。     

两性霉素B长循环脂质体冻干剂的制备工艺研究

目的:对两性霉素B长循环脂质体的冻干工艺进行研究,制备两性霉素B长循环脂质体的冻干剂.方法:采用薄膜-超声法制备了两性霉素B长循环脂质体混悬液.以冻干品再分散后的粒径、包封率为评价指标,考察了不同种类的冻干保护剂和浓度对脂质体冻干品的影响,并对冻干工艺参数进行了优化.结果:选择海藻糖为冻干保护剂,冻干效果较好.制备的冻干剂的平均粒径为(116.8±1.6)nm,药物包封率为(76.0±1.9)%.结论:通过冻干保护剂的筛选和优化冻干工艺参数可以获得最佳的两性霉素B长循环脂质体的冻干品.     

纳米雄黄的粒度分析方法

目的：建立纳米雄黄的粒度分析方法。方法：利用原子力显微镜对纳米雄黄的表观形貌进行直接观察测定,用激光光散射法对纳米雄黄的粒度分布范围进行分析测定。结果：首次得到原子力显微镜下纳米雄黄形貌特征图;激光光散射颗粒度测定仪的测量显示．粒径在30nm以下的纳米雄黄约90％。结论：本研究所采用的原子力显微镜法和激光光散射法快速、简便、准确,可用于纳米雄黄的粒度检测。     

紫杉醇脂质体的制备及其表征

目的制备紫杉醇脂质体并观察其表征。方法采用薄膜分散法制备紫杉醇脂质体,高效液相色谱法测定脂质体中紫杉醇的含量,透射电镜观察脂质体的形貌,激光粒度仪测量粒径和电位。结果制备的脂质体包封率约为（97．95±1．32）％,呈圆形或类圆形,平均粒径在54．6nm左右,电位-40．9mV,体外释放曲线符合Higuchi方程。结论薄膜分散法能制备出粒径小、包封率高稳定性较好的紫衫醇脂质体。     

奥沙利铂-姜黄素脂质体复合物的制备及质量评价

目的：制备共载奥沙利铂-姜黄素脂质体复合物,并对其质控方法进行评价。方法：采用薄膜分散-被动载药技术制备脂质复合物,建立高效液相色谱法测定脂质体复合物含量及包封率,采用Malvern粒度仪测定Zeta电位、动态光散射技术测定粒度与粒度分布。结果：奥沙利铂-姜黄素脂质体复合物的包封率分别为99.02%、97.97%,Zeta电位为（-8.36±1.8） mV;平均粒径为（134.6±1.9） nm,D10（99.2±2.2） nm,D50（137±1.7） nm,D90（189±1.1） nm,D100（248±1.6） nm;脂质体复合物于5℃±3℃稳定性考察6个月,各项考察指标均在标准规定范围内。结论：该技术适合奥沙利铂-姜黄素脂质体复合体的制备,建立的质控方法简单、准确,适合对该脂质体复合物的性质进行评价。     

猪苓多糖长循环脂质体的制备及其质量控制

目的：研究猪苓多糖长循环脂质体的制备方法，并对其质量进行控制。方法：逆相蒸发法制备猪苓多糖长循环脂质体，采用紫外分光光度法测定脂质体中猪苓多糖的包封率和载药量，透射电镜观察形态，激光散射法测定粒径大小，离心加速实验考查稳定性。结果：猪苓多糖长循环脂质体平均粒径为67．8nm，药物平均包封率为93．10％，平均载药量为13．68％。脂质体外观圆整而均匀，渗漏率小，稳定性好。结论：用逆相蒸发法可制备包封率高、稳定性好的猪苓多糖长循环脂质体。质量控制方法简单，快速准确，重复性好。     

黄芩苷脂质体的制备工艺研究

目的:探讨黄芩苷脂质体的制备工艺.方法:采用逆相蒸发法、乙醚注入法和薄膜超声法制备黄芩苷脂质体,SephadexG-50凝胶柱分离脂质体,UV-法测定包封率,Zetasizer3000粒度测定仪测定其粒径,透射电子显微镜进行形态学观察.结果:逆相蒸发法制备的黄芩苷脂质体平均粒径360nm,包封率56.02%;乙醇注入法平均粒径2600nm,包封率26.14%;薄膜-超声法平均粒径1200nm,包封率53.65%.结论:逆相蒸发法制备的黄芩苷脂质体粒径小,包封率高,条件易掌握,可作为黄芩苷脂质体的常规制备方法.     

The Effect of Jet-Milling on Lyophilized Liposomes

Pharmaceutical Research -     

Nanosizing of valsartan by high pressure homogenization to produce dissolution enhanced nanosuspension: pharmacokinetics and pharmacodyanamic study

Purpose: The purpose of the present study was to formulate and evaluate nanosuspension of Valsartan (VAL), a poorly water soluble and low bioavailable drug (solubility of 0.18?mg?mL^?1; 23% of oral bioavailability) with the aim of improving the aqueous solubility thus the bioavailability and consequently better anti-hypertensive activity.

Methods: Valsartan nanosuspension (VAL-NS) was prepared using high-pressure homogenization followed by lyophilisation. The screening of homogenization factors influencing nanosuspension was done by 3-factorial, 3-level Box-Behnken statistical design. Model suggested the influential role of homogenization pressure and cycles on drug nanosizing. The optimized formulation containing Poloxamer^?188 (PXM 188) was homogenized for 2 cycles at 500 and 1000?bar, followed by 5 cycles at 1500 bars.

Results: The size analysis and transmission electron microscopy showed nanometric size range and uniform shape of the nanosuspension. The in vitro dissolution showed an enhanced release of VAL from nanosuspension (VAL-NS) compared to physical mixture with PXM 188. Pharmacodynamic results showed that, oral administration of VAL-NS significantly lowered (p?≤?0.001) blood pressure in comparison to non-homogenized VAL (VAL-Susp) in Wistar rat. The level of VAL in rat plasma treated with VAL-NS showed significant difference (p?≤?0.005) in C_max (1627.47?±?112.05?ng?mL^?1), T_max (2.00?h) and AUC_0→24 (13279.2?±?589.426?ng?h?mL^?1) compared to VAL-Susp that was found to be 1384.73?±?98.76?ng?mL^?1, 3.00?h and 9416.24?±?218.48?ng?h?mL^?1 respectively. The lower T_max value, proved the enhanced dissolution rate of VAL.

Conclusion: The overall results proved that newly developed VAL-NS increased the plasma bioavailability and pharmacodyanamic potential over the reference formulation containing crude VAL.     

In Situ Determination of Delavirdine Mesylate Particle Size in Solid Oral Dosage Forms

Purpose. The in-situ particle size of delavirdine mesylate in dry mix and tablets was determined. Methods. Optical microscopy and fluorescence microscopy combined with image analysis were used for qualitative and quantitative measurements. Results. Using optical microscopy, it was demonstrated qualitatively that fragmentation of the large drug particles was occurring during tablet compression. Quantitative comparisons between dry mix and tablet samples showed that in the dry mix, drug particles remain intact, with particle lengths exceeding 200 m. In the tablets, no particles longer than 100 m had been observed. Analysis of multiple tablet lots revealed consistent in-situ drug particle size distributions, regardless of the original bulk drug particle size. Conclusions. Bulk drug particle size of delavirdine mesylate is not predictive of the particle size in the tablet due to fragmentation of particles during compression. Optical and fluorescence microscopy are valuable tools for probing in-situ particle size in complex matrices.     

Development and characterization of a lovastatin-loaded self-microemulsifying drug delivery system

The objective of the work was to develop, optimize and evaluate a self-microemulsifying drug delivery system of the poorly water soluble drug, lovastatin. Solubility of lovastatin was determined in various vehicles. Ternary phase diagrams were constructed to identify the efficient self-emulsification region using oils, surfactants, and co-surfactants in aqueous environment. Optimized formulations were assessed for drug content, spectroscopic clarity, emulsification time, contact angle, zeta potential, particle size and dissolution studies. Zeta potential was measured in absence and presence of oleylamine, a positive charge inducer. On the basis of similarity and dissimilarity of particle size distribution, formulations were characterized using principal component analysis and agglomerative hierarchy cluster analysis, the multivariate statistical analysis. Transmission electron microscopy of selected formulations (F5–F7) confirmed the spherical shape of globules with no signs of coalescence of globules and precipitation of drug, even after 24?h post dilution in distilled water. The relevance of differences in t_50% and percentage dissolution efficiency was evaluated statistically by two-way ANOVA. Infrared spectroscopy, differential scanning calorimetric and x-ray diffraction studies indicated no incompatibility between drug, oil and surfactants. The results of this study indicate that the self-microemulsifying drug delivery system of lovastatin, owing to nanosize, has potential to enhance its absorption and without interaction or incompatibility between the ingredients.     

The Effect of Size on Uptake of Orally Administered Latex Microparticles in the Small Intestine and Transport to Mesenteric Lymph Nodes

Purpose. The present study examines the relationship between size and particle transit across the mucosal barrier of the gastrointestinal tract to other sites of the body. The extent of particle uptake with increasing size, the tissue distribution and cut-off points for 2–20µm particles is investigated. Methods. An established fluorescent latex particle-young adult rat model is used and particle numbers in small intestine and mesenteric lymph nodes, 0.5 h post administration, counted by fluorescence microscopy in bulk tissue specimens and cryosections. Results. Bulk tissue analysis provides evidence for the presence of particles of all sizes in the Peyer's patch regions, but only for 2 µm particles in the nodal tissues. Microscopy establishes uptake of both 2 and 6 µm particles in most intestinal and nodal tissue sites and compartments. By contrast, uptake of the larger particles is much reduced. Conclusions. Although more of the smaller (2 µm) particles are taken up, particularly by epithelial tissues, the 6µm size appears more efficient in terms of volume translocated to lymph nodes. This could have implications in the therapeutic use of particles for drug and vaccine delivery and for radiation safety.     

Hot-stage microscopy for determination of API fragmentation: comparison with other methods

Although the fragmentation of the active pharmaceutical ingredient (API) is a phenomenon that is mentioned in many literature sources, no well-suited analytical tools for its investigation are currently known. We used the hot-stage microscopy method, already presented in our previous work, and studied the real fragmentation of the tadalafil particles in model tablets which were prepared under different compaction pressures. The morphology, spectral imaging and evaluation of plastic and elastic energies were also analyzed to support the hot-stage method. The prepared blend of tadalafil and excipients was compacted under a several forces from 5 to 35?kN to reveal the trend of fragmentation. The exact fragmentation of tadalafil with increased compaction pressure was revealed by the hot-stage microscopic method and it was in good agreement with plastic and elastic energies. Conversely, spectral imaging, which is being used for this analysis, was considered to be inaccurate methodology as mainly agglomerates, not individual particles, were measured. The availability of the hot-stage microscopic method equips pharmaceutical scientists with an in vitro assessment technique that will more reliably determine the fragmentation of the API in finished tablets and the behavior of the particles when compacted.     

The buccal mucosa as a route for TiO2 nanoparticle uptake

Abstract

The oral cavity, although part of the aero-digestive tract, is still neglected in terms of risk assessment with respect to nanoparticle uptake. If nanoparticles enter the oral cavity, either via oral products or inhaled materials, it is not clear whether they rapidly interact with the mucosae or are swallowed. In this study, interactions of three distinct titanium dioxide (TiO₂) particles (i.e. NM 100, NM 101 and NM 105) with oral tissues are presented. Physicochemical properties were addressed in relevant media, and particle penetration was investigated with an ex vivo model using porcine mucosa. To avoid modification of the particle surfaces via labeling, multiphoton microscopy was introduced as an accurate method to detect TiO₂ particles within the tissue. The spatiotemporal aspects of nanoparticle uptake, as well as the intracellular localization in human epithelial cells, were studied and potential toxic effects were evaluated. Although TiO₂ particles formed large aggregates once dispersed in media, 10–50% remained in the nanoscale range, rapidly interacting with the mucus layer and infecting the epithelium. However, differences in the penetration depth were observed depending on the particle characteristics. NM 100 and NM 105 were found in both the upper part and the lower part of the buccal mucosa, while NM 101 (smallest particle sizes) only penetrated the upper parts. Transport studies revealed that TiO₂ nanoparticles were found in vesicles, as well as freely distributed in the cytoplasm. Cell viability/integrity was not affected negatively; however, NM 105 triggered the production of reactive oxygen species. These data clearly suggest that the oral cavity should be considered in further risk assessment studies.