Dissolution Characteristics of Polycaprolactone-Polylactide Microspheres of Chlorpromazine

Studies were conducted on the preparation of controlled release polycaprolactone-polylactide microcapsules of chlorpromazine and on release of the drug from the microcapsules in pH 7.0 buffer medium. A wide range of release rates of the drug was obtained by simple change in the polymer system. Chlorpromazine was released from the microspheres in a biphasic manner consisting of an initial fast release phase followed by a slow-release phase. Increasing the drug content increased the initial drug release rate but no significant drug loading effect on the second stage dissolution rate was noted. There was no significant effect of particle size on the drug release rate from the microspheres. The swelling property of the microspheres and the agglomerate nature of the sieve fractions may complicate the drug release kinetics and obscure the particle size effect on dissolution rate.     

Dissolution Characteristics of Pharmaceutical Equivalents

The in-vitro release of diltiazem from pharmaceutical equivalents of sustained release tablets, commercially available in Italy, was studied.

The in-vitro release profiles were determined by means of different methods and apparatus. Paddle, basket, Poole, Diffutest and Stricker methods were compared.

The absorption rates in artificial gastric and enteric juices by means of lipid barriers were calculated.

Some preparations showed a diffusion mechanism, some a first-order release.

The differences among the dissolution profiles of the formulations were enhanced with the Strieker method.     

Dissolution Characteristics of Pharmaceutical Equivalents

Abstract

The in-vitro release of diltiazem from pharmaceutical equivalents of sustained release tablets, commercially available in Italy, was studied.

The in-vitro release profiles were determined by means of different methods and apparatus. Paddle, basket, Poole, Diffutest and Stricker methods were compared.

The absorption rates in artificial gastric and enteric juices by means of lipid barriers were calculated.

Some preparations showed a diffusion mechanism, some a first-order release.

The differences among the dissolution profiles of the formulations were enhanced with the Strieker method.     

Preparation and Characteristics of Gelatin Microspheres

Abstract

Gelatin microspheres are prepared by emulsification of a aqueous gelatin solution in a oily phase containing a surfactant, gelation by cooling, dehydration by isopropanol and cross-linking by formaldehyde. The pH, the gelatin concentration in the aqueous solution and the surfactant concentration in the oily phase have some influence on the size distribution of unloaded and loaded microspheres and on the drug contents of microspheres.     

Hydrate Related Dissolution Characteristics of Norfloxacin

Abstract

The effect of moisture and temperature on the physical and chemical stability of solid oral dosage forms of Norfloxacin was studied. The physical properties of the dosage form, i. e. breaking strength and disintegration time were not affected adversely. Dissolution characteristics of Norfloxacin tablets were found to be affected by humidity conditions. Tablets with poor dissolution characteristics were improved to satisfactory rates by exposure to 21–25°C/75% relative humidity. Exposure to lower humidities and higher temperatures adversely affected dissolution rates. Once favorable dissolution rates were attained, however, they remained unchanged in spite of dehydration of the tablets.     

BSA-PLGA微球的优化制备及特性

目的:优化BSA-PLGA微球制备工艺,并对其包封率、形态、体外释放药物及微球包裹前后BSA的稳定性进行评价。方法:以PLGA为载体,采用复乳溶剂挥发法制备BSA-PLGA微球。Micro BCA法测定微球的包封率和载药量,扫描电子显微镜观察微球的形态,激光粒度仪测定粒度及分布,聚丙烯酰胺凝胶电泳(SDS-PAGE)研究微球包裹前后BSA分子结构的完整性,同时考察体外释药性能。结果:根据优化工艺制备的微球外观圆整,平均粒径(2275.8±256.9)nm,包封率(82.59±2.92)%,载药量(13.76±0.49)×10-2%,包裹前后BSA结构稳定,体外释放28天以上,释放曲线符合Higuchi方程。结论:本研究获得了较优化的BSA-PLGA微球制备工艺,所制备的微球具有较高的包封率和明显的缓释效果。     

磁性聚乙烯醇微球的制备及其性质

采用分散聚合法，在Fe3O4磁流体存在下，通过PVA分子单体共聚制备磁性高分子微球。用透射电镜和X射线对磁流体的形貌、粒径进行表征和衍射分析，同时借助于显微拍照和红外光谱，对磁性微球的微观形貌和化学成分进行了研究。通过对比磁性微球的磁响应性及粒径，研究了反应温度、搅拌速度、聚乙烯醇用量、盐酸用量等操作因素对磁性微球性质的影响。结果表明，在70℃操作温度、750r／min的搅拌速度，5ml9％PVA和0．5ml37%盐酸条件下能制备出粒径在8～44μm之间、具有良好磁响应性、表面富含羟基和羧基等官能团的磁性聚乙烯醇微球。     

In Vitro Dissolution Profile of Theophvlline Lorded Ethvl Cellulose Microspheres Preprred by Emulsificrtion Soluent Eurporrtion

Theophylline was entrapped in ethyl cellulose microspheres by a water/oil/water emulsification-solvent evaporation method. Aqueous solution of drug was emulsified into a solution of ethyl cellulose in toluene, containing polyisobutylene as protective colloid, followed by emulsification of this primary emulsion into an external aqueous phase to form a water/oil/water emulsion. Microspheres was formed after solvent evaporation and precipitation of ethyl cellulose. In vitro dissolution profile and effect of polyisobutylene on it were studied.     

磁性聚乙烯醇微球的制备及其性质

采用分散聚合法,在Fe3O4磁流体存在下,通过PVA分子单体共聚制备磁性高分子微球.用透射电镜和X射线对磁流体的形貌、粒径进行表征和衍射分析,同时借助于显微拍照和红外光谱,对磁性微球的微观形貌和化学成分进行了研究.通过对比磁性微球的磁响应性及粒径,研究了反应温度、搅拌速度、聚乙烯醇用量、盐酸用量等操作因素对磁性微球性质的影响.结果表明,在70 ℃操作温度、750 r/min的搅拌速度,5ml 9%PVA和0.5 ml 37%盐酸条件下能制备出粒径在8～44 μm之间、具有良好磁响应性、表面富含羟基和羧基等官能团的磁性聚乙烯醇微球.     

In Vitro Dissolution Profile of Theophvlline Lorded Ethvl Cellulose Microspheres Preprred by Emulsificrtion Soluent Eurporrtion

Abstract

Theophylline was entrapped in ethyl cellulose microspheres by a water/oil/water emulsification-solvent evaporation method. Aqueous solution of drug was emulsified into a solution of ethyl cellulose in toluene, containing polyisobutylene as protective colloid, followed by emulsification of this primary emulsion into an external aqueous phase to form a water/oil/water emulsion. Microspheres was formed after solvent evaporation and precipitation of ethyl cellulose. In vitro dissolution profile and effect of polyisobutylene on it were studied.     

Effect of Amorphous Content on Dissolution Characteristics of Rifampicin

Rifampicin, one of the main first line anti-TB drugs, shows variable bioavailability in different marketed preparations and reasons cited include physiological, degradation, manufacturing/ processing, solid state, and bioavailability assessment procedure. Although the amorphous form of a drug is expected to exhibit higher solubility, the amorphous rifampicin has been reported to have a solubility disadvantage as compared to crystalline form II, which is used in marketed preparations. Amorphous form was generated and characterized by solid-state characterization techniques. Physical powder mixtures of form II with varying amounts of amorphous form were prepared, which were then subjected to solid-state characterization techniques and further evaluated for their dissolution behavior. Differential scanning calorimetry (DSC) scans show that area enclosed by integral of melting endotherm can be used for quantification of crystalline component, which can then be used to estimate amorphous content. No definite trend was evident in powder dissolution of mixtures that could implicate solubility difference of amorphous form. Intrinsic dissolution rate (IDR) results indicate that amorphous content has no effect on dissolution profiles of crystalline rifampicin.     

Preparation and Dissolution Characteristics of Prolonged Release Mebeverine-HCL Beads

Different batches of slow release mebeverine-HCl beads were prepared by pan coating technique using different release retarding polymers viz Eudragit RL₁₀₀, Eudragit RS₁₀₀ and Ethyl cellulose. The thickness of the coats was controlled by changing the amounts of the added polymers. Pre- and overcoating of the beads with bees wax was also carried out. Mixtures of pre-waxed Eudragit RS₁₀₀ coated and uncoated beads in different ratios were prepared to control both drug content and release.

Dissolution profiles of mebeverine HCl from the prepared beads were investigated using USP XX rotating basket method. Prolonged release of mebeverine-HCl was obtained from different batches of the coated beads with the advantage of no initial dumping of the water soluble drug. The release of mebeverine-HCl from the beads coated with acrylic resins and ethyl cellulose as well as waxed acrylic resins coated beads was diffusion controlled according to Higuchi model. Beads coated with ethyl cellulose showed a different release pattern when pre-or overcoated with wax. By altering the ratios of prewaxed Eudragit Rs₁₀₀ coated and uncoated beads in formulated mixtures, it was possible to control both mebeverine-HCl content and release rate.     

Preparation and Dissolution Characteristics of Prolonged Release Mebeverine-HCL Beads

Different batches of slow release mebeverine-HCl beads were prepared by pan coating technique using different release retarding polymers viz Eudragit RL₁₀₀, Eudragit RS₁₀₀ and Ethyl cellulose. The thickness of the coats was controlled by changing the amounts of the added polymers. Pre- and overcoating of the beads with bees wax was also carried out. Mixtures of pre-waxed Eudragit RS₁₀₀ coated and uncoated beads in different ratios were prepared to control both drug content and release.

Dissolution profiles of mebeverine HCl from the prepared beads were investigated using USP XX rotating basket method. Prolonged release of mebeverine-HCl was obtained from different batches of the coated beads with the advantage of no initial dumping of the water soluble drug. The release of mebeverine-HCl from the beads coated with acrylic resins and ethyl cellulose as well as waxed acrylic resins coated beads was diffusion controlled according to Higuchi model. Beads coated with ethyl cellulose showed a different release pattern when pre-or overcoated with wax. By altering the ratios of prewaxed Eudragit Rs₁₀₀ coated and uncoated beads in formulated mixtures, it was possible to control both mebeverine-HCl content and release rate.     

Characteristics of Bicalutamide Solid Dispersions and Improvement of the Dissolution

ABSTRACT

The purpose of our study was to formulate and evaluate bicalutamide (BL) solid dispersions (SD). The physicochemical properties were evaluated by differential scanning calorimetry (DSC), Fourier-Transform infrared (FT-IR) spectroscopy, Powder X-ray diffractometry (PXRD), dissolution studies, and stability studies. The dissolution studies demonstrated that the dissolution of BL from BL-SD increased with an increase in carrier content (PVP K30). X-ray assays and DSC results both confirmed the amorphous state of BL in BL-SD. Stability studies conducted after 6 months showed that BL exhibited excellent stability in the solid dispersion of PVP K30 (1:5).     

Effect of Particle Size on the Dissolution Characteristics of Chlorthalidone

Abstract

The particle size reduction of chlorthalidone by fluid energy milling, Alpine milling and Fitzpatrick milling were evaluated. The desired particle size was achieved by both the fluid energy milling and Alpine milling processes. Alpine mil1ing, however, is a more complex process and is susceptible to product decomposition, whereas fluid energy milling is a simple and efficient process without any risk of product decomposition. The desired particle size cannot be achieved by Fitzmilling because of the low probability of impaction force on particles. The dissolution rate of the chlorthalidone from chlorthalidone/propranolol hydrochloride tablets (25/80 mg) prepared with fluid energy milled chlorthalidone was significantly better than the tablets prepared with Fitzpatrick - milled chlorthalidone. The minimum effective specific surface area of chlorthalidone needed for maximum dissolution in water was found to be around 3.5 m²/g.     

Effect of Particle Size on the Dissolution Characteristics of Chlorthalidone

The particle size reduction of chlorthalidone by fluid energy milling, Alpine milling and Fitzpatrick milling were evaluated. The desired particle size was achieved by both the fluid energy milling and Alpine milling processes. Alpine mil1ing, however, is a more complex process and is susceptible to product decomposition, whereas fluid energy milling is a simple and efficient process without any risk of product decomposition. The desired particle size cannot be achieved by Fitzmilling because of the low probability of impaction force on particles. The dissolution rate of the chlorthalidone from chlorthalidone/propranolol hydrochloride tablets (25/80 mg) prepared with fluid energy milled chlorthalidone was significantly better than the tablets prepared with Fitzpatrick - milled chlorthalidone. The minimum effective specific surface area of chlorthalidone needed for maximum dissolution in water was found to be around 3.5 m²/g.     

Effect of Different Binders on Release Characteristics of Theophylline from Compressed Microspheres

Abstract

Microspheres with 60% w/w drug loading were prepared by the solvent-evaporation method using cellulose acetate butyrate as the encapsulating polymer and micronized anhydrous theophylline as the core material. Four different binders - microcrystalline cellulose, glyceryl palmito-stearate, glyceryl stearate and glyceryl behenate were used to compress three different particle sizes of microspheres. Comparison of the in vitro drug dissolution profiles revealed that drug release was fastest from all the microspheres compressed with microcrystalline cellulose as the binder followed by those compressed with glyceryl palmitostearate, glyceryl stearate and glyceryl behenate.     

Effect of Different Binders on Release Characteristics of Theophylline from Compressed Microspheres

Microspheres with 60% w/w drug loading were prepared by the solvent-evaporation method using cellulose acetate butyrate as the encapsulating polymer and micronized anhydrous theophylline as the core material. Four different binders - microcrystalline cellulose, glyceryl palmito-stearate, glyceryl stearate and glyceryl behenate were used to compress three different particle sizes of microspheres. Comparison of the in vitro drug dissolution profiles revealed that drug release was fastest from all the microspheres compressed with microcrystalline cellulose as the binder followed by those compressed with glyceryl palmitostearate, glyceryl stearate and glyceryl behenate.