Release from or through a wax matrix system. IV. Generalized expression of the release process for a reservoir device tablet.
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Generalization of the release process through the wax matrix layer was examined by use of a reservoir device tablet. The wax matrix layer of the reservoir device tablet was prepared from a physical mixture of lactose and hydrogenated castor oil to simplify the release properties. Release through the wax matrix layer showed zero-order kinetics in a steady state after a given lag time, and could be divided into two stages. The first stage was the formation process of water channel by dissolving the soluble component in the wax matrix layer. The lag time obtained by applying the square root law equation was well connected with the amount of the matrix layer and mixed weight ratio of components in this layer. The second stage was the zero-order release process of drug in the reservoir through the wax matrix layer, because the effective surface area was fixed. The release rate constants were connected with thickness of the matrix layer and permeability coefficient, and the permeability coefficients were connected with the diffusion coefficient of drug and porosity. Hence the release rate constant could be connected with the amount of matrix layer and the mixed weight ratio of components in the matrix layer. It was therefore suggested that the release process could be generalized using the amount of matrix layer and the mixed weight ratio of components in the matrix layer. (+info)
Removal of fine powders from film surface. I. Effect of electrostatic force on the removal efficiency.
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A novel fine particle removal system composed of a corona-discharge neutralizer, a pulse-jet air unit and an image processing system has been developed. First of all, adhesion force between particle and film was directly measured and effect of electrostatic force on the adhesion force was calculated experimentally and theoretically. The electrostatic force was found to be significant, leading to the suggestion that the countermeasure for the electrostatic force was required to effectively remove fine particles. This system was then applied to the removal of fine particles from surface of a gelatin film used for conventional capsule material. The number of particles removed by the system was calculated by an image processing system and number base removal efficiency was computed with and without the elimination of electrostatic charge by the neutralizer. It was found that the difference between the removal efficiency of particles with elimination of electrostatic charge and that of without the elimination showed linear relationship with the electrostatic adhesion force. The data confirmed the necessity of electrostatic charge elimination for the effective removal of fine particles. (+info)
Removal of fine powders from film surface. II. Effect of operating parameters on the removal efficiency.
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In the previous paper, a novel fine particle removal system composed of a corona-discharge neutralizer, a pulse-jet air unit and an image processing system has been developed and applied to the removal of fine particles from film surface. We have calculated the van der Waals and electrostatic forces between particle and film and then reported that the electrostatic force influenced the adhesion characteristics significantly and thus the elimination of electrostatic charge should be necessary for the effective removal of fine particles. In this paper, we have modified the corona-discharge neutralizer for getting much better removal performance. The effect of operating parameters on the removal efficiency was investigated experimentally. The ratio of fine particle remained on the film surface after removal experiment as a function of particle size was measured. It was found that fine particles smaller than 15 microm, which were impossible to remove by other conventional techniques, could be almost completely removed. This method is anticipated to be used in the capsule filling, film packaging and tabletting processes for prevention of stain on lens of video automatic inspection machines, unpredictable movement of electronic devices, and deteriorates of product quality. (+info)
Stabilization of S-adenosyl-L-methionine promoted by trehalose.
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S-adenosyl-L-methionine (SAM), an important metabolic intermediate of mammals, is a well-known therapeutic agent. The molecule is chemically unstable, both in solution and in dry state, and forms different degradation products. Because the chemical instability represents a real problem during the preparation of therapeutic formulations, we investigated the capacity of some sugars to improve the SAM stability over time. In the present work, we demonstrated that the disaccharide trehalose exercises a protective effect towards the lyophilized SAM slackening its degradation (65% of SAM was detected after 50 days at 37 degrees C). A parallel study, performed to stabilize the SAM into lyophilized yeast cells enriched in the sulfonium compound, assessed the positive effect of trehalose also in whole cells, but in lesser measure. (+info)
Differential partitioning of maternal fatty acid and phospholipid in neonate mosquito larvae.
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In animals, lipids are a source of energy, cell membrane components, signaling pathway modulators and emulsifying agents. In egg-laying animals, maternal yolk lipids, imported into the egg before laying, are metabolized or distributed in the developing embryo to serve these functions. Studies with birds, reptiles and insects have described lipid metabolism in adults and in eggs, but no studies have addressed how lipids are distributed in developing organs in the embryo. Here we show that maternal fatty acid and phospholipids segregate differently in tissues of newly hatched mosquito larvae. In the mother, both lipids are colocalized in yolk granules of developing oocytes and distributed evenly. In neonate larvae, however, the maternal fatty acid is stored along the side of the body, especially at the base of the body hair, and in the thorax, where the muscles are located, probably to provide energy for the rapid movements needed to find food immediately after birth. Most maternal phospholipids, however, are concentrated in the motile intestinal gastric caeca, from which they are released into the gut lumen where they may act as emulsifiers, probably to facilitate assimilation of the food the neonate ingests. Similar phenomena were observed in both Anopheles gambiae and Aedes aegypti mosquitoes, suggesting that such differential segregation of lipids is common to both insects. This study may lead to improved delivery of larvicidal agents and to efficient killing of newly hatched mosquito larvae as a control strategy for mosquito-borne diseases. (+info)
The non-ionic detergent Brij 58P mimics chaperone effects.
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The non-ionic detergent Brij 58P is recommended as a stabilizing agent for protein storage; for example, the aggregation-prone chaperone DnaJ can be maintained in solution by low concentrations of Brij 58P. During protein folding studies with alpha-glucosidase, rhodanese and citrate synthase as model proteins, we discovered that the low concentrations of Brij 58P usually added with purified DnaJ to renaturation samples are sufficient to mimic chaperone effects with respect to prevention of protein aggregation. Furthermore, addition of Brij 58P to refolding alpha-glucosidase and citrate synthase enhanced the yield of refolded protein by a factor of two. Thus, Brij 58P can mimic chaperone effects and care should be taken when the substance is used to stabilize chaperone preparations. (+info)
Preparation of antipyretic analgesic by direct compression and its evaluation.
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Direct compression is able to produce tablets at a lower cost than wet granulation and tableting method, due to a fewer items of process validation. In this study, acetaminophen was used as a medicine with various granular diameters to formulate tablets by direct compression, thus evaluating their physical properties. Consequently, direct compression was found effective in formulating tablets with excellent physical properties, with the granular diameter taken into account. It was confirmed that tablets produced by direct compression were similar in physical properties in tablets produced by wet granulation and tableting method. Further, it was suggested that use of a dry-type binder would make it possible to provide a tablet having higher content of the medicine with excellent physical properties. (+info)
A simple method for the selection of a suitable emulsifier based on color difference.
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The purpose of this study was to establish a simple and rapid method for selecting a nonionic surfactant to prepare an emulsion that can maintain a stable emulsification phase. As an index of the degree of emulsification, the white chromaticity of the prepared sample was measured using a color difference meter. When liquid paraffin was used as an oil, the color difference (dE(H)) was shown as a change in a V-shaped curve depending on changes in the hydrophile-lipophile balance (HLB) number of sorbitan ester, polyoxyethylene sorbitan ester, or polyethyleneglycol ester. Although there was a difference in the minimal value of dE(H) in these experiments, the dE(H) was similar to the required HLB of liquid paraffin (HLB=10). On the other hand, no relationship was found between the HLB number and color difference when polyglycerol ester was used. It seems that there was possibility of the effect by the lowering of apparent HLB with a collapse of the hydration. These results indicate that color difference could be utilized for the selection of surfactants, except for polyglycerol ester. (+info)