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1.
Opiate addiction is a serious problem that has now spread worldwide to all levels of society. Buprenorphine has been used for several years for the treatment of opiate addiction. The objective of this project was to develop sustained-release biodegradable microcapsules for the parenteral delivery of buprenorphine. Biodegradable microcapsules of buprenorphine/poly(lactide-co-glycolide) were prepared using two main procedures based on an in-water drying process in a complex emulsion system. These procedures differ in the way the organic solvent was eliminated: evaporation or extraction. The effect of drug loading and the effect of partial saturation of the aqueous phase with the core material during the in-water solvent evaporation were also studied. The efficiency of encapsulation increased from 11% to 34% when the drug loading was decreased from 20% to 5%. There was no significant change in the efficiency of encapsulation when the aqueous phase was partially saturated with buprenorphine. In changing the solvent removal process from evaporation to extraction, no significant change in the efficiency of encapsulation was observed. The microcapsules prepared by the solvent evaporation were smooth and spherical. However, the microcapsules prepared by the extraction of the organic solvent lost their surface smoothness and became slightly irregular and porous compared with the other batches. The average particle size of the microcapsules was between 14 and 49 μm. The cumulative drug release was between 2% and 4% within the first 24 hr. A sustained drug release continued over 45 days.  相似文献   

2.
Opiate addiction is a serious problem that has now spread worldwide to all levels of society. Buprenorphine has been used for several years for the treatment of opiate addiction. The objective of this project was to develop sustained-release biodegradable microcapsules for the parenteral delivery of buprenorphine. Biodegradable microcapsules of buprenorphine/poly(lactide-co-glycolide) were prepared using two main procedures based on an in-water drying process in a complex emulsion system. These procedures differ in the way the organic solvent was eliminated: evaporation or extraction. The effect of drug loading and the effect of partial saturation of the aqueous phase with the core material during the in-water solvent evaporation were also studied. The efficiency of encapsulation increased from 11% to 34% when the drug loading was decreased from 20% to 5%. There was no significant change in the efficiency of encapsulation when the aqueous phase was partially saturated with buprenorphine. In changing the solvent removal process from evaporation to extraction, no significant change in the efficiency of encapsulation was observed. The microcapsules prepared by the solvent evaporation were smooth and spherical. However, the microcapsules prepared by the extraction of the organic solvent lost their surface smoothness and became slightly irregular and porous compared with the other batches. The average particle size of the microcapsules was between 14 and 49 microns. The cumulative drug release was between 2% and 4% within the first 24 hr. A sustained drug release continued over 45 days.  相似文献   

3.
Microencapsulation has been important for engineering, biology, medicine, and several other fields of science. Microencapsulation is an effective way to protect the encapsulated material (e.g. an aqueous solution or pharmaceutical drug) and control its release to the external environment. Microcapsules are also used for producing anticorrosion systems and, in this case, studies about polymeric microcapsules containing acid solutions are relevant. In this paper, polystyrene microcapsules containing demineralized water were produced. The influence of the core-to-shell ratio, evaporation temperature, and the presence of sodium chloride and a surfactant on the yield of the microencapsulation process was evaluated. Microcapsules were characterized by scanning electron microscopy (SEM), and thermogravimetry that revealed the morphology and thermal behavior of microcapsules in response to changing core-to-shell ratios. SEM images showed mononuclear microcapsules with smooth surfaces. The results indicated that a core-to-shell ratio of 2:1 showed the best encapsulation performance under the conditions of this study. An increase in yield of about 38% was achieved by reducing the evaporation temperature. In addition, the yields obtained in this research are considerably higher than those found in literature.  相似文献   

4.
Ibuprofen was microencapsulated with ethylcellulose using the solvent evaporation method. The effect of production variables on the properties of the microcapsules and drug release from them is described. Results show that size distribution, drug loading and the amount of free drug on the surface of the microcapsules is affected by production variables. The release of drug from the microcapsules was observed to be strongly influenced by parameters affecting the presence of uncoated drug on the microcapsule surface.  相似文献   

5.
The objectives of present work was to design and characterize the rabeprazole sodium loaded microcapsules prepared by solvent evaporation technique using ethyl cellulose (EC) based various mucoadhesive polymer, followed by a triple coating with Eudragit L100. The Box-behnken design (BBD) was applied for optimization of formulations containing EC, HPMCK100M and Eudragit L100 as factors for selected responses like entrapment efficiency, mucoadhesive property and drug release in 24 h. The prepared microcapsules were characterized for particle size, drug content, swelling index, mucoadhesive strength, and in vivo antiulcer activity. FT-IR studies revealed that there was no drug-polymer interaction. SEM studies revealed that microcapsules were non-aggregated, spherical shape and smooth appearance. In vitro drug release data from microcapsules was fitted to different kinetic models to explain release profiles. The correlation coefficient value (r2) indicated that the drug release followed Higuchi model. Analysis of variance (ANOVA) showed significant difference in the release of drug from all formulations at p < 0.05 level. Accelerated stability study of optimized formulation (F4) upto 6 months showed there was no change in drug content and release characteristics during storage. In vivo antiulcer activity showed that the optimized microcapsules were able to protect rat stomach against ulcer formation vis-à-vis aqueous solution of the drug showed only negligible and minimum effect.  相似文献   

6.
Sustained-release micro-/nanospheres of the ketorolac tromethamine (KTC) were prepared using four different techniques viz., single emulsion solvent evaporation, high pressure homogenization, spray drying, and using a microreactor. Ethyl cellulose (EC) was used as an encapsulating agent for the preparation of sustained-release micro-/nanospheres of KTC. The Plackett–Burman design was employed for design of the experiments. The resulting micro-/nanospheres were characterized for their size, morphology, encapsulation efficiency, and in vitro drug release performance. Interactions between the KTC and EC were quantified by Fourier transform infrared (FTIR) spectroscopy and X-ray powder diffractometry (XRPD). Particle morphology characterization was performed using field emission scanning electron microscopy. The micro-/nanospheres showed encapsulation efficiency of 42.34–89.33% by the solvent evaporation technique, 76.36–91.13% by the high-pressure homogenization technique, 70.74–79.68% by spray drying, and 79.00–89.49% by the microreactor technique. The micro-/nanospheres were found to be spherical and oval with smooth surface. The FTIR analysis confirmed no interaction of KTC with EC polymer. The XRPD analysis revealed good dispersion of the drug within the micro-/nanospheres formulation. Sustained KTC release profile over 12?h was achieved successfully by EC polymer. In conclusion, EC sustained-release micro-/nanospheres containing KTC can be prepared successfully using different techniques.  相似文献   

7.
5-fluorouracil-SiO2-poly(L-lactide) (5-Fu-SiO2-PLLA) microcapsules were prepared in a novel process of solution-enhanced dispersion by supercritical CO2 (SEDS). The SiO2 nanoparticles were loaded with 5-Fu by adsorption at the first place, then the 5-Fu-SiO2 nanoparticles were coated with PLLA by a modified SEDS process. The resulted microcapsules were characterized by scanning electron microscope (SEM), laser diffraction particle size analyzer, Fourier transform infrared spectrometer (FTIR) and thermogravimeter-differential scanning calorimeter (TG-DSC). The drug load, encapsulation efficiency and drug release profiles were also determined. The resulted microcapsules exhibited a rather spherical shape, smooth surface, and a narrow particle size distribution with a mean particle size of 536 nm. The drug load and encapsulation efficiency of the samples were 0.18% and 80.53%, respectively, 25.05% of 5-Fu was released in the first half hour, then drug released in a sustained process, which was much slower than that of without coated by PLLA. The results indicated that the modified SEDS process could be used to produce drug-polymer microcapsules with a core-shell structure, high encapsulation efficiency and sustained drug release effect.  相似文献   

8.
Chlorpheniramine maleate was complexed with a carboxylic acid cation-exchange resin and the complexes were microencapsulated with polymethyl methacrylate using an emulsion-solvent evaporation technique. Microcapsules of larger mean diameters resulted from polymer solutions of increased viscosities. Addition of 3% finely divided solids to the encapsulation vehicle resulted in smaller microcapsules, whereas a 6% concentration had the opposite effect, an increased capsule mean diameter. Emulsion stabilizers, such as magnesium stearate, up to a 1% concentration reduced microcapsule size by as much as 50%. The process efficiency ranged from 73% to 99%, depending on the formulation and manufacturing conditions used. The rate of drug release from the microcapsules was directly related to the amount of polymer deposited and inversely proportional to the capsule size.  相似文献   

9.
Curcumin, the main active constituent of turmeric herb (Curcuma longa L.) have been reported to possess many medicinal values. The application of curcumin in dermatological preparations is limited by their intense yellow color property, which stains the fabric and skin. The objectives of this study were to reduce the color staining effect and enhance the stability of curcumin via microencapsulation using gelatin simple coacervation method. As for curcumin, ethanol and acetone were used as coacervating solvents. Curcumin was dispersed in ethanol while dissolved in acetone. Irrespective of the types of coacervating solvents used, microencapsulation resolved the color-staining problem and enhanced the flow properties and photo-stability of curcumin. Nevertheless, it was found that more spherical curcumin microcapsules with higher yield, higher curcumin loading, and higher entrapment efficiency were obtained with acetone than ethanol. The in vitro release of curcumin after microencapsulation was slightly prolonged. Further evaluation of the effects of solubility of core materials in coacervating solvent or polymeric aqueous solution using six different drug compounds, namely, ketoconazole, ketoprofen, magnesium stearate, pseudoephedrine HCl, diclofenac sodium, and paracetamol, suggested that the solubility of core materials in aqueous polymeric solution determined the successful formation of microcapsules. Microcapsules could only be formed if the core materials were not dissolved in the aqueous polymeric solution while the core materials could either be dissolved or dispersed in the coacervating solvent. In summary, microencapsulation not only circumvents the color-staining problem but also improved the stability and flowability of curcumin. The solubility of core material in aqueous polymeric solution plays a pivotal role in determining the successful formation of microcapsules.  相似文献   

10.
采用反溶剂法,以肉桂醛为芯材,乙基纤维素(EC)为壁材制备肉桂醛微胶囊,研究了不同芯壁比对微胶囊包埋率及形貌的影响;采用扫描电镜对所得微胶囊的表面形貌进行观察,借助红外光谱和热重分析等对其形成机理能进行了分析,并对其缓释性进行了测试。结果表明,当芯壁比为1∶3时包埋率最大,达到83%,载药量为21%,微胶囊为分散性好、粒径200 nm~1μm的球形粒子。红外光谱、热重分析结果表明EC可以通过自组装将肉桂醛包裹于其形成的疏水性空腔内部。微胶囊存放7 d后,其中的肉桂醛释放率仅为23%,而肉桂醛混合物中肉桂醛的释放率达到了54%,表明肉桂醛微胶囊具有一定缓释性。  相似文献   

11.
Curcumin, the main active constituent of turmeric herb (Curcuma longa L.) have been reported to possess many medicinal values. The application of curcumin in dermatological preparations is limited by their intense yellow color property, which stains the fabric and skin. The objectives of this study were to reduce the color staining effect and enhance the stability of curcumin via microencapsulation using gelatin simple coacervation method. As for curcumin, ethanol and acetone were used as coacervating solvents. Curcumin was dispersed in ethanol while dissolved in acetone. Irrespective of the types of coacervating solvents used, microencapsulation resolved the color-staining problem and enhanced the flow properties and photo-stability of curcumin. Nevertheless, it was found that more spherical curcumin microcapsules with higher yield, higher curcumin loading, and higher entrapment efficiency were obtained with acetone than ethanol. The in vitro release of curcumin after microencapsulation was slightly prolonged. Further evaluation of the effects of solubility of core materials in coacervating solvent or polymeric aqueous solution using six different drug compounds, namely, ketoconazole, ketoprofen, magnesium stearate, pseudoephedrine HCl, diclofenac sodium, and paracetamol, suggested that the solubility of core materials in aqueous polymeric solution determined the successful formation of microcapsules. Microcapsules could only be formed if the core materials were not dissolved in the aqueous polymeric solution while the core materials could either be dissolved or dispersed in the coacervating solvent. In summary, microencapsulation not only circumvents the color-staining problem but also improved the stability and flowability of curcumin. The solubility of core material in aqueous polymeric solution plays a pivotal role in determining the successful formation of microcapsules.  相似文献   

12.
Abstract

Chlorpheniramine maleate was complexed with a carboxylic acid cation-exchange resin and the complexes were microencapsulated with polymethyl methacrylate using an emulsion-solvent evaporation technique. Microcapsules of larger mean diameters resulted from polymer solutions of increased viscosities. Addition of 3% finely divided solids to the encapsulation vehicle resulted in smaller microcapsules, whereas a 6% concentration had the opposite effect, an increased capsule mean diameter. Emulsion stabilizers, such as magnesium stearate, up to a 1% concentration reduced microcapsule size by as much as 50%. The process efficiency ranged from 73% to 99%, depending on the formulation and manufacturing conditions used. The rate of drug release from the microcapsules was directly related to the amount of polymer deposited and inversely proportional to the capsule size.  相似文献   

13.
The nanoparticles-embedded microcapsules (NEMs) with smooth surface, good sphericity, excellent dispersivity and uniform particle size distribution were prepared by emulsification combined with electrospraying to extend the sustained release performance of the embolic microcapsules loading capecitabine (CAP). The sodium alginate and chitosan with good biocompatibility were used as the materials and CAP as a small-molecule model drug. The drug loading, encapsulation efficiency and drug release of CAP in the NEMs were investigated. The results showed that the drug-loading and encapsulation efficiency both increased with the increment of chitosan and CAP concentration. The maximum values of drug loading and encapsulation efficiency were 1.97 and 18.01 % respectively when initial CAP concentration was 5.0 g/L and chitosan molecular weight 100 kDa. The cumulative release rate of CAP released from the NEMs was lower than 30 % in 0.5 h, which indicated that there was no obvious initial burst release behavior. In the subsequent 240 h, the release results confirmed that the NEMs had better sustained release properties compared to pure microcapsules, and it might be a new anticancer drug delivery system in the future studies.  相似文献   

14.
This work was aimed to design and optimize a long acting microsphere-based injectable formulation of aripiprazole by using D-optimal experimental design methodology. Microspheres were prepared by solvent evaporation method using PLGA and cholesterol as release rate retardant materials. The microspheres were characterized for their encapsulation efficiency, particle size, surface morphology, residual solvent content, and drug release behavior. Contour plots were plotted to study the encapsulation and release behaviour of the drug from the microspheres. Desirability technique was used for the optimization of microsphere formulation composition. By using an optimum blend of drug and cholesterol in the microsphere formulation it was possible to attain a consistent drug release for a period of 14 days. The results have confirmed that the D-optimal experimental design technique can be successfully employed for designing the long acting microsphere dosage form.  相似文献   

15.
This work was aimed to design and optimize a long acting microsphere-based injectable formulation of aripiprazole by using D-optimal experimental design methodology. Microspheres were prepared by solvent evaporation method using PLGA and cholesterol as release rate retardant materials. The microspheres were characterized for their encapsulation efficiency, particle size, surface morphology, residual solvent content, and drug release behavior. Contour plots were plotted to study the encapsulation and release behaviour of the drug from the microspheres. Desirability technique was used for the optimization of microsphere formulation composition. By using an optimum blend of drug and cholesterol in the microsphere formulation it was possible to attain a consistent drug release for a period of 14 days. The results have confirmed that the D-optimal experimental design technique can be successfully employed for designing the long acting microsphere dosage form.  相似文献   

16.
This work examines the release of diclofenac sodium from ethylcellulose (EC) microcapsules made up of different drug to polymer ratios. The release process was found to follow the Higuchi square root equation and not the zero-order or first order equations. However, for drug to polymer ratio of 1:1, a critical time (θ) was reached beyond which the release rate was lower than that predicted on the basis of the Higuchi square root equation. Dissolution experiments in 0.1N HCL revealed that less than 1.5% of the encapsulated drug was released in 6 h. This finding indicates the suitability of the EC microcapsules for enteric-coated preparations. The in vitro release of diclofenac sodium from microcapsules of different drug to polymer ratios was compared with that from a commercial sustained-release product. A distinct similarity between the release profile of the commercial product with that obtained for the 1:2 drug to polymer microcapsules was noted. The in vivo work included determination of the serum drug profile following oral administration of the microcapsules and the commercial product to rabbits. The obtained serum concentration time profile of the EC microcapsules exhibited a sustained-release pattern similar to the commercial product and consistent with the in vitro results.  相似文献   

17.
The purpose of this study was the development and characterization of wheat gluten microspheres for use as controlled release devices, and the evaluation of the effect of the addition of poly (ethylene glycol) (PEG). Diltiazem hydrochloride was used as the model drug in the in vitro release essay. The physical–chemical and morphological properties of the microspheres were evaluated, as well as their encapsulation efficiency. Porosity varied with the presence or absence of PEG. The diltiazem encapsulation efficiency was 72.8% and 96.7% for wheat gluten and gluten/PEG 95/05 microspheres, respectively. The DSC and FTIR results indicated interactions between the microparticles and additives used. In the in vitro release tests it was observed that, for all the studied systems, the burst effect occurred in the first 2 h of release and the microspheres prepared with PEG had a faster release rate. In the attempt to elucidate the release mechanism, the systems were treated based on two well known mathematical models: the Higuchi and the power law. It was found that the microsphere release mechanism is not exclusively diffusion-controlled and, probably, the release occurs through a combination of partial diffusion through the swelling matrix and hydrophilic pores.  相似文献   

18.
Commercially available antibacterial semisolid preparations intended for topical application provide only short-term drug release. A sustained kinetics is possible by exploitation of a biodegradable polymer carrier. The purpose of this work is to formulate a mucoadhesive system with aciclovir (ACV) based on a solid molecular dispersion of this drug in poly(lactic-co-glycolic acid) branched on tripenterythritol (PLGA/T). The ACV incorporation into PLGA/T was carried out either by solvent method, or melting method, or plasticization method using various plasticizers. The drug–polymer miscibility, plasticizer efficiency and content of residual solvent were found out employing DSC. Viscosity was measured at the shear rate range from 0.10 to 10.00?s?1 at three temperatures and data were analyzed by Newtonian model. The mucoadhesive properties were ascertained in the tensile test on a mucin substrate. The amount of ACV released was carried out in a wash-off dissolution test. The DSC results indicate a transformation of crystalline form of ACV into an amorphous dissolved in branched polyester carrier, and absence of methyl formate residuals in formulation. All the tested plasticizers are efficient at Tg depression and viscosity decrease. The non-conventional ethyl pyruvate possessing supportive anti-inflammatory activity was evaluated as the most suitable plasticizer. The ACV release was strongly dependent on the ethyl pyruvate concentration and lasted from 1 to 10 days. The formulated PLGA/T system with ACV exhibits increased adhesion to mucosal hydrophilic surfaces and prolonged ACV release controllable by degradation process and viscosity parameters.  相似文献   

19.
Abstract

This work examines the release of diclofenac sodium from ethylcellulose (EC) microcapsules made up of different drug to polymer ratios. The release process was found to follow the Higuchi square root equation and not the zero-order or first order equations. However, for drug to polymer ratio of 1:1, a critical time (θ) was reached beyond which the release rate was lower than that predicted on the basis of the Higuchi square root equation. Dissolution experiments in 0.1N HCL revealed that less than 1.5% of the encapsulated drug was released in 6 h. This finding indicates the suitability of the EC microcapsules for enteric-coated preparations. The in vitro release of diclofenac sodium from microcapsules of different drug to polymer ratios was compared with that from a commercial sustained-release product. A distinct similarity between the release profile of the commercial product with that obtained for the 1:2 drug to polymer microcapsules was noted. The in vivo work included determination of the serum drug profile following oral administration of the microcapsules and the commercial product to rabbits. The obtained serum concentration time profile of the EC microcapsules exhibited a sustained-release pattern similar to the commercial product and consistent with the in vitro results.  相似文献   

20.
Context: Transdermal spray (TS) of clotrimazole (CTZ) was formulated to improve the drug transport through the skin up to 12?h to achieve the antifungal efficacy.

Objective: The aim of present study was to formulate and evaluate antifungal transdermal spray to improve the permeation of clotrimazole across the skin and to decrease the dosing frequency in fungal infection.

Materials and methods: Different ratios of ethanol and acetone and various grades of eudragit and ethyl cellulose were evaluated according to six criteria: viscosity, drying time, stickiness, appearance and integrity on skin and water washability. Propylene glycol (PG) and polyethylene glycol 400 (PEG 400) were used in the study as plasticizer and solubilizer. The TS was evaluated for in vitro drug release, spray angle, spray pattern, average weight per dose, pH, drug content, evaporation time, leak test and antifungal efficacy study.

Results and discussion: Eudragit E100 and blend of ethanol and acetone (80:20) satisfied the desired criteria. The selection of optimized batch was based on the results of in vitro drug release, spray pattern and spray angle. The optimized batch showed the spray angle <85° and uniform spray pattern. The formulation containing PG showed higher drug release than PEG 400. The inclusion of eutectic mixture consisting of camphor and menthol (1:1) showed improved drug transport through the rat skin and larger mean zone of inhibition indicating the improved antifungal efficacy.

Conclusion: The TS of CTZ can be an innovative and promising approach for the topical administration in the fungal diseases.  相似文献   

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