Navegando por Autor "Soares, Luiz Alberto Lira"
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Item Agitation during lipoplex formation harmonizes the interaction of siRNA to cationic liposomes.(2012) Barichello, José Mario; Kizuki, Shinji; Tagami, Tatsuaki; Soares, Luiz Alberto Lira; Ishida, Tatsuhiro; Kikuchi, Hiroshi; Kiwada, HiroshiWe recently demonstrated that agitation during lipoplex formation (vorLTsiR) improves the gene knockdown effect of siRNA because the resultant decrease in lipoplex size leads to an enhanced uptake by cells. In furthering this line of research, the present study was focused on the interaction of siRNA to cationic liposomes during lipoplex preparation. A fluorescence resonance energy transfer (FRET) study indicated that the application of agitation in the presence of siRNA effectively reorganized positively charged lipids (DC-6-14 and DOPE) in an order that effectively promoted further electrostatic interaction between the negatively charged phosphate backbone of siRNA and the positively charged lipids in the cationic liposome membrane. A circular dichroism (CD) study indicated that the agitation did not bring about a change in the A-form helix of siRNA, therefore the interactions between the lateral anionic groups of siRNA – responsible for the characteristic bands of the A-form helix – and cationic liposomes were effectively promoted. Factorial design coupled with response surface methodology was used to statistically analyze the influence of vortex speed and time and siRNA dose on the in vitro gene knockdown effects of siRNA-lipoplex that were spontaneously formulated (spoLTsiR) along with that formulated under agitation (vorLTsiR). The analysis indicated that vortex speed plays the most important role in enhancing the gene knockdown effect of siRNA among the three variables, although all three are important. It was concluded that the high energy transmitted by applying agitation during lipoplex formation harmonized the interaction of siRNA to positively charged lipids (DC-6-14 and DOPE) in cationic liposomes, resulting in a superior gene knockdown efficacy of vorLTsiR compared to spoLTsiR. Our study suggests that the preparation procedure is one of the critical factors in producing the enhanced gene knockdown effect of siRNA.Item Comparative bioavailability of a generic and two compounded naproxen sodium suspensions administered to rats.(2010) Solon, Lílian Grace da Silva; Guerra, Gerlane Bernardo Coelho; Araújo, Aurigena Antunes de; Barichello, José Mario; Urizar, José Pérez; Soares, Luiz Alberto LiraThe purpose of this study was to determine naproxen concentrations in rat plasma samples by HPLC and to compare the bioavailability of a generic and two compounded naproxen sodium suspensions (test 1 and test 2). Analysis was run at a fl ow rate of 1.2 mL.min-1 with a mobile phase of acetonitrile: NaH2PO4 0.01 M pH 4.00 (50:50, v/v) at 280 nm, using a C18 column (150 mm x 4.6 mm, 5 μm). The calibration curve was linear (R2 = 0.9987) over the range of 0.25 - 200 μg.mL-1. The precision for inter and intra-day analysis ranged from 2.46% to 12.39%. Cmax, Tmax and AUCt were 191.25 ± 11.17 μg.mL-1, 1.00 ± 0.106 h and 2438.16 ± 291.34 μg.h.mL-1 for the reference drug, 188.22 ± 24.78 μg.mL-1, 1.06 ± 0.092 h and 1755.02 ± 228.90 μg.h.mL-1 for test 1, and 160.50 ± 10.58 μg.mL-1, 0.66 ± 0.102 h and 1955.28 ± 142.80 μg.h.mL-1 for test 2. No signifi cant differences were found based on analysis of variance, with mean values and 90% CI of test2/reference ratio (Cmax 83.92% and AUCt 80.19%). For test1/reference ratio, the result was Cmax 98.41% and AUCt 71.98%. Based on these results, it can be concluded that the validated method was successfully applied to this study; the test 1 formulation failed to demonstrate a bioequivalence to the reference drug; however, the test 2 and reference naproxen sodium suspension were bioequivalent in terms of the rate and extent of absorption under these conditions.