The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Bice Conti - One of the best experts on this subject based on the ideXlab platform.
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Testing of in vitro dissolution behaviour of Microparticulate drug delivery systems
Drug Development and Industrial Pharmacy, 2008Co-Authors: Bice Conti, Ida Genta, Paolo Giunchedi, Tiziana ModenaAbstract:AbstractNo official dissolution method exists concerning Microparticulate drug delivery systems. The purpose of this work is the evaluation of different dissolution methods commonly used to test the in vitro release behaviour of Microparticulate drug delivery systems. The influence of different environmental conditions, as stirring speed, ionic strength and presence of surfactant, on drug release is also evaluated.Four dissolution methods, based on different equipments (USP dissolution test apparatus, rotating bottle apparatus, shaker incubator, recycling flow through cell), are performed on the same batch of indomethacin loaded poly-D, L-lactide (PDLLA) microspheres prepared by spray drying. The results obtained with the methods tested show the influence of in vitro dissolution method employed and of the environmental conditions on drug release profile.
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biodegradable microspheres for the intravitreal administration of acyclovir in vitro in vivo evaluation
European Journal of Pharmaceutical Sciences, 1997Co-Authors: Bice Conti, Paolo Giunchedi, Claudio Bucolo, Claudia Giannavola, Giovanni Puglisi, Ubaldo ConteAbstract:Abstract The purpose of this work is the preparation of Microparticulate systems containing acycloguanosine, their characterization, and the description of in vitro release profiles and humoral drug concentration after intravitreal administration. Polylactides and polylactide–co-glycolide biopolymers with different molecular weights ranging between 3000 and 109 000 were employed. Microparticle preparation has been performed by spray-drying. Good results in terms of encapsulation efficiency have always been obtained. Results show that morphological characteristics of the Microparticulate systems obtained and their in vitro dissolution behaviour, depend on polymer molecular weight. In vivo evaluation has been performed by intravitreal administration of microspheres in rabbits. The results show that in vivo sustained release of drug is achieved.
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bioadhesive microspheres for ophthalmic administration of acyclovir
Journal of Pharmacy and Pharmacology, 1997Co-Authors: Ida Genta, Bice Conti, Paola Perugini, F Pavanetto, A Spadaro, G PuglisiAbstract:The bioavailability of acyclovir to the ophthalmic epithelium is low and when the drug is administered in ophthalmic ointment it must be applied every four hours. An emulsification technique has been used to prepare acyclovir-loaded chitosan microspheres with the aim of promoting the prolonged release of drug and increasing its ocular bioavailability. The Microparticulate drug-delivery systems obtained have been characterized for their morphology and physicochemical characteristics by in-vitro dissolution tests and in-vivo ocular administration to rabbits. The results show that the microspheres obtained are always quite small--the diameters of 90% of the particles are < or = 25 microns (i.e. d 90% never exceeds 25 microns) and physicochemical characterization shows that the drug is homogeneously dispersed in an amorphous state inside the microspheres. The in-vitro dissolution profile of acyclovir from chitosan microspheres is slower than that for the raw drug. Results from in-vivo ocular administration of acyclovir-loaded microspheres to the rabbit eye show prolonged high concentrations of acyclovir and increased AUC values. The Microparticulate drug-carrier seems a promising means of topical administration of acyclovir to the eye.
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Biodegradable microspheres for the intravitreal administration of acyclovir: in vitro/in vivo evaluation
European Journal of Pharmaceutical Sciences, 1997Co-Authors: Bice Conti, Paolo Giunchedi, Claudio Bucolo, Claudia Giannavola, Giovanni Puglisi, Ubaldo ConteAbstract:Abstract The purpose of this work is the preparation of Microparticulate systems containing acycloguanosine, their characterization, and the description of in vitro release profiles and humoral drug concentration after intravitreal administration. Polylactides and polylactide–co-glycolide biopolymers with different molecular weights ranging between 3000 and 109 000 were employed. Microparticle preparation has been performed by spray-drying. Good results in terms of encapsulation efficiency have always been obtained. Results show that morphological characteristics of the Microparticulate systems obtained and their in vitro dissolution behaviour, depend on polymer molecular weight. In vivo evaluation has been performed by intravitreal administration of microspheres in rabbits. The results show that in vivo sustained release of drug is achieved.
C R Arnold - One of the best experts on this subject based on the ideXlab platform.
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co feeding Microparticulate diets with algae toward eliminating the need of zooplankton at first feeding in larval red drum sciaenops ocellatus
Aquaculture, 2000Co-Authors: Juan Pablo Lazo, Maria Teresa Dinis, Joan G Holt, Cindy Faulk, C R ArnoldAbstract:The effect of adding algae to the culture water used to rear red drum larvae was evaluated in terms of growth, survival and digestive enzyme activity. Red drum larvae were subjected to one of the following dietary regimes from first feeding (day 3 post-hatch) to day 14: (1) zooplankton supplemented with algae (L-A), (2) zooplankton without algae (L-NA), (3) a Microparticulate diet with algae (M-A) and (4) the Microparticulate diet alone (M-NA). The presence of algae in the rearing tanks improved growth of red drum larvae for both types of feeds. Growth was significantly higher (P<0.05) in larvae reared in the presence of algae (L-A and M-A) than in larvae raised in the corresponding treatments without algae (L-NA and M-NA). Red drum larvae raised on the Microparticulate diet and algae (M-A) grew as well as the zooplankton treatment with no algae (L-NA), and were not significantly different from the L-A treatment. The larvae fed the Microparticulate diet in the absence of algae (M-NA) were significantly smaller than the other three treatments. These results were consistent for two separate feeding trials. Final survival was highly variable in all treatments; nevertheless, mean final survival values were 30% higher in treatment L-A compared to L-NA (14.1 and 10.1%, respectively) and 42% higher in M-A than for M-NA (6.2 and 4.0%, respectively). Significantly higher trypsin and aminopeptidase activity was observed in the presence of algae, which may have influenced the digestion of the diet. Our results demonstrate that red drum larvae may be raised on a Microparticulate diet from first feeding without the use of zooplankton.
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Co-feeding Microparticulate diets with algae : Toward eliminating the need of zooplankton at first feeding in larval red drum (Sciaenops ocellatus)
Aquaculture, 2000Co-Authors: Juan Pablo Lazo, Maria Teresa Dinis, Cindy Faulk, G. Joan Holt, C R ArnoldAbstract:The effect of adding algae to the culture water used to rear red drum larvae was evaluated in terms of growth, survival and digestive enzyme activity. Red drum larvae were subjected to one of the following dietary regimes from first feeding (day 3 post-hatch) to day 14: (1) zooplankton supplemented with algae (L-A), (2) zooplankton without algae (L-NA), (3) a Microparticulate diet with algae (M-A) and (4) the Microparticulate diet alone (M-NA). The presence of algae in the rearing tanks improved growth of red drum larvae for both types of feeds. Growth was significantly higher (P
Andreas Bernkopschnurch - One of the best experts on this subject based on the ideXlab platform.
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nasal delivery of human growth hormone in vitro and in vivo evaluation of a thiomer glutathione Microparticulate delivery system
Journal of Controlled Release, 2004Co-Authors: Verena M. Leitner, Davide Guggi, Alexander H. Krauland, Andreas BernkopschnurchAbstract:Abstract It was the aim of this study to develop and evaluate a nasal Microparticulate delivery system for human growth hormone (hGH) based on the thiomer polycarbophil-cysteine (PCP-Cys) in combination with the permeation mediator glutathione (GSH). Microparticles were prepared by dissolving PCP-Cys/GSH/hGH (7.5:1:1.5), PCP/hGH (8.5:1.5), and mannitol/hGH (8.5:1.5) in demineralized water, followed by lyophilization and micronization. Particles were evaluated with regard to size distribution and swelling behavior using a laser diffraction particle size analyzer. The release of fluorescence-labelled hGH from microparticles was determined in Franz diffusion chambers. In vivo studies in rats were performed comparing the nasal bioavailability achieved by PCP-Cys/GSH/hGH microparticles with that of unmodified PCP/hGH microparticles and mannitol/hGH powder. PCP-Cys/GSH/hGH and PCP/hGH microparticles showed a comparable size distribution (80% in the range of 4.8–23 μm) and swelled to almost fourfold size in phosphate-buffered saline (PBS). Both formulations exhibited almost identical sustained drug release profiles. The intranasal administration of the PCP-Cys/GSH/hGH Microparticulate formulation resulted in a relative bioavailability of 8.11±2.15%, which represents a 3-fold and 3.3-fold improvement compared to that of PCP/hGH microparticles and mannitol/hGH powder, respectively. The study suggests that the PCP-Cys/GSH/hGH nasal Microparticulate formulation might represent a promising novel tool for the systemic delivery of hGH.
Ubaldo Conte - One of the best experts on this subject based on the ideXlab platform.
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biodegradable microspheres for the intravitreal administration of acyclovir in vitro in vivo evaluation
European Journal of Pharmaceutical Sciences, 1997Co-Authors: Bice Conti, Paolo Giunchedi, Claudio Bucolo, Claudia Giannavola, Giovanni Puglisi, Ubaldo ConteAbstract:Abstract The purpose of this work is the preparation of Microparticulate systems containing acycloguanosine, their characterization, and the description of in vitro release profiles and humoral drug concentration after intravitreal administration. Polylactides and polylactide–co-glycolide biopolymers with different molecular weights ranging between 3000 and 109 000 were employed. Microparticle preparation has been performed by spray-drying. Good results in terms of encapsulation efficiency have always been obtained. Results show that morphological characteristics of the Microparticulate systems obtained and their in vitro dissolution behaviour, depend on polymer molecular weight. In vivo evaluation has been performed by intravitreal administration of microspheres in rabbits. The results show that in vivo sustained release of drug is achieved.
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Biodegradable microspheres for the intravitreal administration of acyclovir: in vitro/in vivo evaluation
European Journal of Pharmaceutical Sciences, 1997Co-Authors: Bice Conti, Paolo Giunchedi, Claudio Bucolo, Claudia Giannavola, Giovanni Puglisi, Ubaldo ConteAbstract:Abstract The purpose of this work is the preparation of Microparticulate systems containing acycloguanosine, their characterization, and the description of in vitro release profiles and humoral drug concentration after intravitreal administration. Polylactides and polylactide–co-glycolide biopolymers with different molecular weights ranging between 3000 and 109 000 were employed. Microparticle preparation has been performed by spray-drying. Good results in terms of encapsulation efficiency have always been obtained. Results show that morphological characteristics of the Microparticulate systems obtained and their in vitro dissolution behaviour, depend on polymer molecular weight. In vivo evaluation has been performed by intravitreal administration of microspheres in rabbits. The results show that in vivo sustained release of drug is achieved.
Richard Ipsen - One of the best experts on this subject based on the ideXlab platform.
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Effect of hydration of Microparticulated whey protein ingredients on their gelling behaviour in a non-fat milk system
Journal of Food Engineering, 2016Co-Authors: Isabel Celigueta Torres, Gülsüm Mutaf, Flemming H. Larsen, Richard IpsenAbstract:Abstract Two types of Microparticulated whey protein ingredients with different particle characteristics were added to a non-fat milk system and allowed to hydrate for different periods of time prior to heat treatment. Differences during acidification of the milk systems were investigated by rheology and 1 H nuclear magnetic resonance spin-spin relaxation. The amounts of more or less mobilised water were shown to differ depending on the type of Microparticulated whey protein. Large protein microparticles did not actively participate in gel network formation and showed an increased fraction of more mobilised water, and thus higher syneresis upon storage. An enhanced surface reactivity was shown in small microparticles which may also be related to the increased interaction potential of the native whey proteins present.
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Using fractal image analysis to characterize microstructure of low-fat stirred yoghurt manufactured with Microparticulated whey protein
Journal of Food Engineering, 2012Co-Authors: Isabel Celigueta Torres, Jose Manuel Amigo Rubio, Richard IpsenAbstract:Differences in the microstructure of low fat yoghurt manufactured with Microparticulated whey proteins used as fat replacer were investigated. Images were obtained by confocal laser scanning microscopy and studied using a technique for image analysis that combines an initial 2D-wavelet compression followed by fractal analysis and inspection of the fractal curves by principal components analysis (PCA). One commercial and three experimental Microparticulated ingredients with different chemical characteristics were used in the yoghurt formulations and compared to both full and low fat yoghurts without fat replacer. The results showed that the amount of native and soluble whey proteins present in the microparticles had a positive influence on the structure of the formed gel. The created structure, dominated by dense aggregates and low amount of serum, had an increased degree of self similarity or fractality with yoghurts in which fat was present.