Caracterização físico-química do fármaco antichagásico benznidazol

Currently, benznidazole (BNZ) is a unique therapeutic alternative available in Brazil to treat Chagas disease. Despite its traditional medical use, little is known about the chemical nature of this drug. A detailed study of the physicochemical properties of BNZ was performed using multiple assays. Thermal, diffractometric, morphological and reological drug profiles were obtained. The partition coefficient and solubility results allowed this drug to be classified as a class IV drug according to the biopharmaceutical classification system. This information will be useful for the development of more effective BNZ formulations and for establishing the quality profile of BNZ

Estudo da ação de poliânions sobre a atividade das enzimas colesterol esterase e colesterol oxidase, utilizando lipoproteínas plasmáticas como substratos

Exportado OPUSMade available in DSpace on 2019-08-14T00:35:43Z (GMT). No. of bitstreams: 1 disserta__o_de_mestratdo___p_s_gradua__o_bioq_imica_e_imunologia__guilherme__hideki_yoshizane_cost.pdf: 2510236 bytes, checksum: bcba77e6807c332b6df5df35e43f0082 (MD5) Previous issue date: 3Sugiuchi et al. (1995) desenvolveram um método direto para a determinação de colesterol proveniente da lipoproteína de alta densidade (HDL), sem a necessidade de procedimentos pré-analíticos. O teste consiste na formação de complexos solúveis das apoB100-lipoproteínas com o poliânion -ciclodextrina sulfato, o que reduz a ação das enzimas colesterol esterase e colesterol oxidase sobre lipoproteínas de baixa densidade (LDL), muito baixa densidade (VLDL) e quilomicra. A inibição total da catálise enzimática sobre as apoB100-lipoproteínas é alcançado após a ligação covalente de moléculas de polietilenoglicol às superfícies das enzimas. Após essa ligação, somente as partículas de HDL ficam disponíveis para ação da colesterol esterase e colesterol oxidase. O presente trabalho verificou a capacidade de inibição da reação catalisada pelas enzimas colesterol esterase e colesterol oxidase pelos poliânions: ácido fosfotúngstico, sacarose octassulfato, sulfato de condroitina e -ciclodextrina sulfato. Foram determinados parâmetros cinéticos para a enzima colesterol esterase nativa e após adição de polietilinoglicol à sua superfície utilizando calorimetria de titulação isotérmica. Os resultados evidenciaram que o ácido fosfotúngstico é capaz de inibir satisfatoriamente a ação das enzimas sobre as apoB100-lipoproteínas. Os valores da constante de Michaelis-Menten (Km) para colesterol esterase nativa utilizando HDL e LDL foram de 4,26 M de linoleato de colesterila e 13,14 M de linoleato de colesterila, respectivamente. Após a adição do polietilenoglicol à enzima o Km da enzima utilizando HDL como substrato foi alterado para 21,6 M de linoleato de colesterila. Os resultados desse estudo fornecem o embasamento para o desenvolvimento de um reagente para a determinação de colesterol HDL.Sugiuchi et al. (1995) developed a direct method to determine cholesterol from high density lipoprotein, with no need for pre-analytical procedures. The assay consists of the formation apoB100-lipoproteins' soluble complexes with -cyclodextrin sulfate polyanion, which reduces the action of the enzymes cholesterol esterase and cholesterol oxidase over low density lipoprotein (LDL), very low density lipoprotein (VLDL) and chylomicra. Total inhibition of the enzymatic catalysis over apoB100-lipoproteins is achieved after the covalent bonding of polyethyleneglycol on the enzymes surfaces. Only the HDL's particles are available for the catalysis of cholesterol esterase and cholesterol oxidase. This study verified the inhibition of the reactions catalyzed by cholesterol esterase and cholesterol oxidase by the polyanions: phosphotungstic acid, sucrose octasulfate, chondroitin sulfate and - cyclodextrin sulfated. Kinetics parameters for the native enzyme cholesterol esterase and after the bonding with polyethyleneglycol were also determinate. The results showed that phosphotungstic acid is able to inhibit satisfactorily the enzymes' action over apoB100-lipoproteins. The Km's values for native cholesterol esterase with HDL and LDL were 4,26 M of cholesteryl linoleate and 13,14 M of cholesteryl linoleate, respectively. After the bound of polyethyleneglycol on the cholesterol esterase surface the enzimes Km for HDL was altered to 21,6 M of cholesteryl linoleate. The results of this study provide the knowledge to develop a reagent used to determine HDL cholesterol

Homocysteine: validation and comparison of two methods using samples from patients with pulmonary hypertension

Introduction and objective:The determination of homocysteine plasma levels has been reported as a risk marker of interest in severe diseases involving endothelial injury and associated with the development or progression of atherosclerotic lesions and thrombus formation. The aims of this study were to validate method for quantification of plasma homocysteine by high performance liquid chromatography (HPLC) with fluorimetric detection, and to compare the results obtained from patients with pulmonary hypertension by HPLC with those obtained by spectrophotometric enzymatic cycling (S-Ec) method.Materials and methods:The validation parameters, such as linearity, matrix effect, precision, accuracy, detection and quantitation limits, and robustness of the method were evaluated aiming to demonstrate that it is suitable for the intended use. The data obtained in the quantification of homocysteine using the validated method (HPLC) and the spectrophotometric enzymatic cycling (S-Ec) method, were compared.Results:The method was precise, accurate, and robust; it also had good recovery and showed no matrix effect. The linearity covered a range of 5.0-85.0 µmol/l and the limits of detection and quantification were 1.0 µmol/l and 3.4 µmol/l, respectively. The results obtained for homocysteine determination by HPLC and S-Ec methods were comparable.Conclusion:The validated HPLC method showed good performance for quantification of plasma homocysteine levels, while S-Ec method provided results for homocysteine comparable with those obtained by the validated method; therefore, this methodology is a potential alternative of automated method for clinical laboratories

Development of effervescent tablets containing benznidazole complexed with cyclodextrin.

Objectives: Benznidazole (BNZ), the primary chemotherapy agent used to treat Chagas disease, has poor aqueous solubility, which results in low bioavailability. The purpose of this work was to develop stable effervescent tablets using an inclusion complex of BNZ with cyclodextrin (CD). Method: In the first phase, different CDs were evaluated according to their ability to improve the aqueous solubility of BNZ. Then, inclusion complexes of BNZ in the solid state were produced by the kneading method and the complexes were evaluated using several physical–chemical assays. Finally, effervescent tablets were prepared according to a complete 32 factorial design. The effects of the concentration of CD and effervescent mixture on the dissolution rate and physical stability of tablets were evaluated. Key findings: Hydroxypropyl-b-cyclodextrin produced the greatest improvement in the aqueous solubility of BNZ, almost 20-times greater than the water system. Solid systems produced with BNZ and CD showed physical–chemical interactions and increased the drug dissolution rate, suggesting the formation of a true solid inclusion complex. Moreover, the effervescent matrix of the tablets was effective in improving the dissolution behaviour of BNZ complexed with CD. Conclusions: Effervescent tablets produced using an inclusion complex of BNZ with CD suggest a possible improvement in the bioavailability of BNZ, and this could represent a relevant advance in Chagas therapy