Effect of preparation method and cholesterol on drug encapsulation studies by phospholipid liposomes

Unilamellar liposomes, prepared from synthetic lipid mixture of DMPC and DMPG either by sonication or extrusion, were used to entrap water soluble and water insoluble molecules to investigate the efficacy of encapsulation by different liposome preparation methods. In the case of entrapment of hydrophilic protein cytochrome-C, the solutions were subjected to a series of ultrafiltration steps to eliminate any free protein outside the vesicles. It was observed that the protein could be encapsulated by the vesicles only if cholesterol was present in the bilayer. The release of cytochrome-C was observed spectrophotometrically upon vesicle-breakdown. The amount of protein encapsulated depended on the method of preparation and was found to be 10 times greater in extruded liposomes compared to those produced by sonication. Hydrophobic Vitamin E, on the other hand, could be encapsulated in the liposome bilayer, independently of the presence of cholesterol and the method of preparation. These fundamental results can be used to develop more efficient drug encapsulations and to have better understanding about their release.     

黄芩素固体脂质纳米粒包封率测定及体外释放度考察

目的测定黄芩素固体脂质纳米粒的包封率,并考察其体外释放规律。方法溶剂扩散法制备脂质纳米粒,高速离心法分离纳米粒和游离药物,HPLC法测定包封率并考察其体外释放规律。结果测得纳米粒的平均包封率为60.73%,其体外释放规律符合H iguch i动力学方程。结论黄芩素固体脂质纳米粒有较高的包封率,在体外具有良好的缓释作用。     

Comparative bioavailability of 5-aminosalicylic acid from a controlled release preparation and an azo-bond preparation

Background: Knowledge of the bioavailability of 5-aminosalicylic acid (5-ASA, mesalazine) from the different 5-ASA-containing drugs is important for rational therapy of inflammatory bowel diseases. Methods: The local and systemic bioavailability of 5-ASA from a controlled release 5-ASA preparation (Pentasa—2, 4 or 6 g/day) was investigated and compared with the azo-bond 5-ASA preparation olsalazine (Dipenturn— 2 g/day) in 13 healthy volunteers during steady state conditions. Results: The therapeutically relevant parameter of 5-ASA at the rectal level, expressed as the mean concentration in faecal water, showed a significant trend towards higher concentrations with increasing Pentasa dose: 9.2 mmol/L, 19.0 mmol/L and 24.4 mmol/L, respectively. The concentration of olsalazine 2 g/day was 16.0 mmol/L. The concentration of the metabolite N-acetyl-5-aminosalicylic acid (Ac-5-ASA) did not rise with increasing Pentasa dose, indicating saturable presystemic acetylating capacity of 5-ASA. Total urinary excretion of 5-ASA and Ac-5-ASA, as a percentage of the daily ingested 5-ASA dose, remained constant on the three Pentasa doses, but there was a significant increase in the 5-ASA fraction. Mean steady state plasma concentrations of 5-ASA and Ac-5-ASA were significantly higher on Pentasa 4 g/day and 6 g/day than on 2 g/day. Values on Pentasa 2 g/day were comparable with those on olsalazine 2 g/day. Conclusions: The study confirmed that 5-ASA is released from Pentasa in a predictable manner, the amount released increasing with dose. Olsalazine is an excellent generator of 5-ASA in the colon.     

Chitosan microparticle preparation for controlled drug release by response surface methodology

The objectives were to investigate the effects of formulation variables on the release of drug and to optimize the formulation of chitosan microparticles loaded with drug for controlled release using response surface methodology. Chitosan microparticles were prepared by dropping a chitosan solution into sodium tripolyphosphate (TPP) through ionic cross-linking. The release behaviour of felodipine as a model drug was affected by preparation variables. A central composite design was used to evaluate and optimize the effect of preparation variables, chitosan concentration (X1), the pH of the TPP solution (X2) and cross-linking time (X3) on the cumulative per cent drug release (Y) in 24 h. Chitosan concentration and cross-linking time affected negatively the release of felodipine, while the pH of the TPP did so positively and was the highest influential factor. The optimum rate of drug release, 100% in 24 h, was achieved at 1.8% chitosan concentration, a pH 8.7 for the TPP solution and 9.7 min cross-linking time.     

Chitosan microparticle preparation for controlled drug release by response surface methodology

The objectives were to investigate the effects of formulation variables on the release of drug and to optimize the formulation of chitosan microparticles loaded with drug for controlled release using response surface methodology. Chitosan microparticles were prepared by dropping a chitosan solution into sodium tripolyphosphate (TPP) through ionic cross-linking. The release behaviour of felodipine as a model drug was affected by preparation variables. A central composite design was used to evaluate and optimize the effect of preparation variables, chitosan concentration (X₁), the pH of the TPP solution (X₂) and cross-linking time (X₃) on the cumulative per cent drug release (Y) in 24 h. Chitosan concentration and cross-linking time affected negatively the release of felodipine, while the pH of the TPP did so positively and was the highest influential factor. The optimum rate of drug release, 100% in 24 h, was achieved at 1.8% chitosan concentration, a pH 8.7 for the TPP solution and 9.7 min cross-linking time.     

盐酸小檗碱结肠控释微丸的制备和体外释放测定

目的制备盐酸小檗碱结肠控释微丸,并初步研究其体外释放行为。方法采用挤出滚圆法制备盐酸小檗碱微丸,旋转包衣锅Eudragit S100包衣,UV法在不同释放条件下测定释放度。结果及结论盐酸小檗碱结肠控释微丸在体外实验中可满足结肠定位释放的要求,使用该方法制备盐酸小檗碱结肠控释微丸有效、可控。     

硝苯地平缓控释制剂制备技术研究进展

目的总结近年来国内外硝苯地平缓控释制剂制备技术的研究进展,为硝苯地平缓控释制剂的开发研制提供参考。方法查阅了目前主要的硝苯地平缓控释制剂制备技术如缓控释片技术（骨架型技术、渗透泵技术、脉冲技术和薄膜包衣技术）、缓控释胶囊技术、微囊技术、微球技术、脂质体技术和纳米技术,以及一些新技术的文献和资料。结果和结论为了更好的满足高血压患者的用药需求,研制可以实现平穗给药和择时给药的硝苯地平缓控释制剂已经成为必然的趋势。     

阿西美辛控释胶囊的研制及释放度研究

采用薄膜包衣制成阿西美辛控释微丸，用此微丸制成含阿西美辛３０ｍｇ的胶囊。测定其释药情况表明，该胶囊可达到预期的控释效果。     

Clinical and pharmacological study of a novel controlled release preparation of salbutamol.

This study compared the efficacy of 8 mg controlled release (CR) salbutamol tablets twice daily with standard 4 mg salbutamol tablets four times daily in patients with chronic obstructive airways disease. There was significant bronchodilation in both treatment groups as measured by standard spirometry (P less than 0.05). With the CR preparation there was significantly less wheeze (P less than 0.05) and significantly reduced requirement for rescue bronchodilator (P less than 0.05). Salbutamol levels measured hourly on the final day of each treatment period showed that the drug profile in the CR group was smoother, without the troughs and peaks seen with standard tablets.     

Multilayer alginate/protamine microsized capsules: encapsulation of alpha-chymotrypsin and controlled release study

Stable polyelectrolyte microcapsules with size 6.5 microm were produced by means of the layer-by-layer adsorption of sodium alginate and protamine to surface of melamine formaldehyde microparticles. Core decomposition at low pH leads to formation of polyelectrolyte multilayered capsules filled with alginate gel. A proteolytic enzyme, alpha-chymotrypsin, was loaded into these microcapsules by embedding in alginate gel with high efficacy. The protein in the capsules was found to retain a high physiological activity of about 70% showed with fluorescent product. The protein was found to keep inside the microcapsules in water and acid (HCl solution, pH 1.7) during 24 and 4 h, respectively, while 75-85% of protein can be revealed in supernatant after 6 h incubation at pH 8.0 (0.05 M Tris buffer) in the presence of 2.5% w/v of sodium deoxycholate. The release rate of enzyme from multilayer alginate/protamine microcapsules can be regulated by additional adsorption of polyelectrolytes onto the microcapsules with encapsulated protein. Such protein-loaded capsules can be proposed as a drug delivery system with controllable release properties.     

药师对住院患者缓控释制剂正确使用干预研究

目的促进住院患者合理使用缓控释制剂。方法药师审核医嘱,干预不合理使用缓控释制剂医嘱。分别抽取干预前2009年,干预后2010年和2011年的11月中4 d医嘱进行分析统计。结果缓控释制剂的医嘱正确率逐年升高,从49.5%到91.0%,差异具有显著性意义（P〈0.01）。结论药师积极干预口服药缓控释制剂的使用,促进了临床合理用药工作的开展。     

度米芬控释片的研制及其工艺条件的考察

目的:制备度米芬控释片,并对工艺条件进行考察。方法:采用正交设计以体外溶出为指标,对包衣材料种类、包衣剂用量、致孔剂用量进行处方筛选。结果:优化后的结果可以满足中国药典对缓控释制剂体外溶出的要求。结论:该片剂制备工艺简单易行,适合工业化生产。     

Development of a binary lipid nanoparticles formulation of itraconazole for parenteral administration and controlled release

The principal aim of this study was to develop an intravenous formulation of itraconazole (ITZ) using lipid nanoparticles based on binary mixture of liquid and solid lipids. Lipid nanoparticles were developed to provide the controlled release of ITZ as well as to improve the solubility of ITZ. Lipid nanoparticles were prepared with tristearin as a solid lipid, triolein as a liquid lipid, and a surfactant mixture of eggPC, Tween 80 and DSPE-PEG₂₀₀₀. ITZ was incorporated at the concentration of 20 mg/g. Lipid nanoparticles were manufactured by high-pressure homogenization method. The particle size and polydispersity index (PI) of lipid nanoparticles were below 280 nm and 0.2, respectively. Zeta potentials and incorporation efficiencies of lipid nanoparticles were around ?30 mV and above 80%, respectively. Lipid nanoparticles containing 1% of liquid lipid showed the smallest particles size and the highest incorporation efficiency. Results from SEM, DSC and PXRD revealed that ITZ in lipid nanoparticles exists in an amorphous state. Release rates were increased as the amount of liquid lipid in lipid core increased, demonstrating that the release of ITZ from lipid nanoparticles could be controlled by modulation of the amount of liquid lipid in lipid core. Pharmacokinetic studies were performed after intravenous administration of lipid nanoparticles in rats at the dose of 5 mg/kg. The plasma concentration of ITZ was prolonged after intravenous administration of lipid nanoparticles. It is concluded that binary lipid nanoparticles could control the release and pharmacokinetic parameters of ITZ.     

Modelling of the solvent evaporation method for the preparation of controlled release acrylic microspheres using neural networks

The purpose of the present study was to model the solvent evaporation procedure for the preparation of acrylic microspheres by using artificial neural networks (ANNs) to obtain an understanding of the selected preparative variables. Three preparative variables, the concentration of the dispersing agent (sucrose stearate), the stirring rate of emulsion system, and the ratio of polymers (Eudragit RS-L) were studied, each at different levels, as input variables. The response (output) variables examined to characterize microspheres and drug release were the size of the microspheres and T 63.2%, the time at which 63.2% of drug is released. The results were also analysed by the multiple linear regression (MLR) to provide a comparison with the ANN methodology. Although both ANN and MLR methods were found to be similar in characterizing the process studied, the results showed that an ANN method gave a better prediction than the MLR method. For the size values of the microspheres, the predictability of the ANN model was quite high (R² = 0.9602) based on the input variables. A relationship between these variables and size values of microspheres was also obtained by the MLR model (R² = 0.9050). The performances of both models for the release data frommicrospheres based on the sameinput variables were at the level of 53%. According to the results, the ANN methodology can provide an alternative to the traditional regression methods, as a flexible and accurate method to study process and formulation factors.     

Modelling of the solvent evaporation method for the preparation of controlled release acrylic microspheres using neural networks

The purpose of the present study was to model the solvent evaporation procedure for the preparation of acrylic microspheres by using artificial neural networks (ANNs) to obtain an understanding of the selected preparative variables. Three preparative variables, the concentration of the dispersing agent (sucrose stearate), the stirring rate of emulsion system, and the ratio of polymers (Eudragit RS-L) were studied, each at different levels, as input variables. The response (output) variables examined to characterize microspheres and drug release were the size of the microspheres and T63.2%, the time at which 63.2% of drug is released. The results were also analysed by the multiple linear regression (MLR) to provide a comparison with the ANN methodology. Although both ANN and MLR methods were found to be similar in characterizing the process studied, the results showed that an ANN method gave a better prediction than the MLR method. For the size values of the microspheres, the predictability of the ANN model was quite high (R2 = 0.9602) based on the input variables. A relationship between these variables and size values of microspheres was also obtained by the MLR model (R2 = 0.9050). The performances of both models for the release data from microspheres based on the same input variables were at the level of 53%. According to the results, the ANN methodology can provide an alternative to the traditional regression methods, as a flexible and accurate method to study process and formulation factors.     

In vitro investigation of lipid implants as a controlled release system for interleukin-18

Operating on the inductive and effective phases of an anti-tumor immune response and uncovering pivotal functions that may reduce cancer cell growth, interleukin-18 (IL-18) appears to be an attractive candidate for the sustained local adjuvant immunotherapeutic treatment of brain gliomas. The objective of this work was to develop IL-18 loaded lipid implants as a controlled delivery system. For the preparation of protein loaded triglyceride matrix material, a solid-in-oil (s/o) dispersion technique was chosen for which protein particles in the micrometer range were first prepared by co-lyophilization with polyethylene glycol (PEG). Implants of 1 mm diameter, 1.8 mm height and 1.8 mg weight were manufactured by compression of the powder mixture in a specially designed powder compacting tool. The in vitro release behavior of 125I-Bolton-Hunter-radiolabeled IL-18 was assessed in a continuous-flow system. A cell culture assay was established for the determination of bioactivity of released IL-18. Implants showed a continuous release of 10-100 ng IL-18 per day for 12 days. A progressive integrity loss was observed with ongoing release, which would be related to protein degradation during incubation. The initially released fraction proved complete retention of bioactivity, indicating that the manufacturing procedure had no detrimental effects on protein stability.     

萘普生脉冲释药片的研制及体外释药影响因素考察

目的:制备萘普生脉冲释药片并考察体外释放的影响因素。方法:以乙基纤维素和丙烯酸树脂Ⅱ号为包衣材料制备包衣片,通过体外释放度的测定来考察片芯及包衣材料等因素对脉冲释药片体外释放的影响。结果:崩解剂的用量、包衣液中致孔剂的含量及包衣膜的厚度为影响药物体外释放的主要因素。结论:萘普生脉冲释药片在体外具有脉冲释药特性。     

渗透泵型控释片制备工艺研究进展

渗透泵型控释制剂作为缓控释制剂的典型代表,是以渗透压作为释药动力,以零级释放动力学为特征的一种制剂技术,已成为目前国内外研究开发的热点。本文就口服渗透泵型控释片的制备工艺研究进展情况进行了综述。     

阿克他利固体脂质纳米粒的制备及体外释药特性

目的:制备阿克他利固体脂质纳米粒研究外释药模式。方法:单因素考察的基础上,以正交试验设计优化,筛选最佳处方和制备工艺。透射电镜观察固体脂质纳米粒的形态,激光散射测定Zeta电位和粒度分布,超速离心法测定阿克他利固体脂质纳米粒的包封率,研究体外释放速度。结果:所制固体脂质纳米粒外观形态圆整,粒度分布为50~200nm,平均粒径为120nm。Zeta电位为-17.14mV,包封率为51.20%。体外释药特性研究具有良好的缓释特性,在0~12h符合100Q=38.536t1/4-16.859(r=0.999 0),13~648h符合100Q=13.907t1/4 28.32(r=0.999 2)。结论:通过优化处方和制备工艺,采用乳化蒸发-低温固化法制备阿克他利固体脂质纳米粒,其体外释药具有明显的缓释、长效作用。