Biomedical subjects

W P Oliveira

Publications and source records attributed to W P Oliveira.

5 recordsLinked to original sources

PubMed2006

In vitro dissolution studies of sodium diclofenac granules coated with Eudragit L-30D-55 by fluidized-bed system.

The objective of this work was to study the dissolution process of sodium diclofenac granules coated with a polymeric suspension of Eudragit L-30D-55 by fluidized bed. Methacrylic acid-methylmetacrylate copolymer, also known as Eudragit, has been used as a pH sensitive coating material to protect drug substances prior to delivery to the human intestines. The sodium diclofenac granules were prepared by wet granulation technology using microcrystalline cellulose (MICROCEL), sodium diclofenac, and polivinilpirrolidone K-30. The granules coating operation was carried out in a fluidized bed with top spraying by a double-fluid nozzle. The dissolutions studies of the coated granules were performed in triplicate in a dissolution test station according to USP XXIII (1995) "in vitro testing requirements" Method A (paddle method, rotation of 100 RPM and temperature fixed at 37 degrees C). The dissolution mediums were 0.1N HCl solution and a pH 6.8 phosphate buffer solution, following the pH change dissolution procedure specified in USP for enteric-coated articles: 2 h of exposure to 750 mL of 0.1N HCl followed by testing in 1000 mL of pH 6.8 phosphate buffer, the pH being adjusted with 250 mL of 0.2 M tribasic sodium phosphate solution. The released amount of sodium diclofenac was periodically determined by UV spectrophotometry at wavelength of 276 nm, using a spectrophotometer UV-VIS HP 8453. The coated product showed gastric resistance properties confirming the feasibility of the fluidized bed for applying enteric coating in granules and pharmaceutical powders.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2003

Evaluation of the anti-ulcerogenic activity of a dry extract of Maytenus ilicifolia Martius ex. Reiss produced by a jet spouted bed dryer.

We undertook the present study to evaluate the activity of the dried extract of Maytenus ilicifolia against stomach ulcers and in the increase of the volume and pH of the gastric juice of Wistar rats, as a model to evaluate the viability of the Jet Spouted Bed Dryer for the production of dry-extracts of medicinal Brazilian plants. The extract was obtained from the drying of a hydro-alcoholic extract with drying aid (40% of colloidal SiO2 related to solid content in the concentrated extract, at a concentration of 15.82% in water). The drying conditions employed were: Temperature of the spouting gas 150 degrees C, feed flow-rate of hydro-alcoholic extract 16.0 g/min, feed flow rate of the spouting gas 1.67 m3/min and static bed height 7.0 cm. Wistar rats received three different doses (140, 280 and 420 mg/kg) of the dried extract by intraperitoneal way and, after 60 minutes, were immobilized with wire screen and placed at temperature of 4 degrees C for two hours (cold-restraint stress). The animals were sacrificed and the stomach removed, examined and the volume and pH of the gastric secretion determined. A significant reduction in the ulceration index, was observed as well as a significant increase of the volume and of the pH of the gastric secretion for all doses administered. This is an indication that the preparation of dried extracts by the Jet spouted bed technique does not alter the biological activity of Maytenus ilicifolia.

Animals↗

PubMed2003

O/w dispersions development containing liquid crystals.

Liquid crystals are defined as the intermediary state between solid and liquid and also called of mesomorphous phase or crystalline phase, presenting characteristics of the mentioned physical states. For the simple emulsions that intermediary phase can act as forms of encapsulation of drugs providing its controlled liberation and besides, it can increase cutaneous hydration. These characteristics evidences the differentiation of the developed formulations and the use of the same ones in the release of new cosmetic vehicles. In that research we use vegetable oils (coffee, tomato), mineral oil, surfactants like phosphorics esthers (fractions A and B) and distilled water as aqueous phase. The stable formulations were submitted to stability physic-chemical preliminary tests (pH values determination, electric conductivity values, centrifugation and thermal stress) and later the compositions were submitted to accelerated stability tests (cold-hot cycle in the following temperature conditions--4 +/- 2 degrees C, 25 +/- 2 degrees C and 45 +/- 2 degrees C). Crystalline phase was identified by microscopy polarization. The recently prepared formulations and aged formulations (after 30 days) were appraised for rheology.

Cosmetics↗

PubMed2001

Evaluation of the tablet coating by the conventional spouted-bed process.

The purpose of this paper was to present an analysis of the tablet coating by the conventional spouted-bed process. To analyze the equipment performance, the rate of increase of the tablets mass, K1, and the adhesion coefficient eta were determined as a function of the feed flow rate of coating suspension Ws; of the Reynolds number Rep; of the flow rate of atomizing gas Wat, and of the cone base angle gamma. To analyze the product quality, the uniformity of coating mass deposition onto the tablet's surface was used. Three different procedures for description of kinetics growth, weighing method, image analysis, and measurements with a micrometer were used to verify the validity of the commonly used weighing method. Comparison between experimental results of kinetics growth with estimates obtained by a literature model was also performed. A tendency toward an increase in K1 and in eta with the feeding flow rate of coating suspension Ws was detected. The weighing method can be used for the process analysis. The kinetics of growth can be described by the growth model used. The variable that produce more pronounced effect on K1 and eta was the feed flow rate of coating suspension, the weighing method describes very well the increase of particle diameter with coating time, the growth model can be used for the describe the kinetics of growth during the coating operation, and the coating does not deposit uniformly onto the tablet's surface.

Chemistry, Pharmaceutical↗

PubMed1997

Disaccharidase levels in normal epithelium of the small intestine of rats with iron-deficiency anemia.

Iron-deficiency anemia is the nutritional deficiency most frequently occurring throughout the world, which manifests as a complex systemic disease involving all cells, affecting enzyme activities and modifying protein synthesis. In view of these considerations, the objective of the present study was to determine the effects of iron-deficiency anemia on disaccharidases and on the epithelial morphokinetics of the jejunal mucosa. Newly weaned male Wistar rats were divided into 4 groups of 10 animals each: C6w received a standard ration containing 36 mg elemental iron per kg ration for 6 weeks; E6w received an iron-poor ration (5-8 mg/kg ration) for 6 weeks; C10w received an iron-rich ration (36 mg/kg ration) for 10 weeks; E10w received an iron-poor ration for 6 weeks and then an iron-rich ration (36 mg/kg) for an additional 4 weeks. Jejunal fragments were used to measure disaccharidase content and to study cell proliferation. The following results were obtained: 1) a significant reduction (P < 0.001) of animal weight, hemoglobin (Hb), serum iron and total iron-binding capacity (TIBC) in group E6w as compared to C6w; reversal of the alterations in Hb, serum iron and TIBC with iron repletion (E10w = C10w); animal weights continued to be significantly different in groups E10w and C10w. 2) Sucrase and maltase levels were unchanged; total and specific lactase levels were significantly lower in group E6w and this reduction was reversed by iron repletion (E10w = C10w). 3) The cell proliferation parameters did not differ between groups. On the basis of these results, we conclude that lactase production was influenced by iron deficiency and that this fact was not related to changes in cell population and proliferation in the intestinal mucosa.

Anemia, Iron-Deficiency↗