Pullulan: an advantageous natural polysaccharide excipient to formulate tablets of alendronate-loaded microparticles

Neste trabalho relata-se a preparação de comprimidos pela compressão direta de micropartículas contendo alendronato de sódio, utilizando o pullulan como diluente. As propriedades dos comprimidos de pullulan foram comparadas com as de comprimidos de celulose microcristalina e de lactose. Os comprimidos de pullulan mostraram baixa variação no peso médio, espessura e teor. Por outro lado, estes apresentaram altos valores de dureza comparados aos preparados com os outros excipientes. Através dos estudos de liberação in vitro pode-se observar que apenas o pullulan foi capaz de manter a gastrorresistência e as propriedades de liberação das micropartículas, o que se deve à sua capacidade de proteger as partículas do dano causado pela força de compressão. Dessa forma, o pullulan foi considerado um excipiente vantajoso para a preparação de comprimidos microparticulados.This work reports the preparation of tablets by direct compression of sodium alendronate-loaded microparticles, using pullulan as filler. The tableting properties of pullulan were compared with those of microcrystalline cellulose and lactose. Pullulan tablets showed low variations in average weight, thickness and drug content. Moreover, these tablets exhibited a higher hardness compared to the other excipients. In vitro release studies showed that only pullulan was capable to maintain gastroresistance and release properties of microparticles, due to its ability to protect particles against damage caused by compression force. Thus, pullulan was considered an advantageous excipient to prepare tableted microparticles

Formulation of gastroresistant tablets containing sodium alendronate-loaded blend microparticles

Sodium alendronate is an antiresorptive drug used for the treatment of postmenopausal osteoporosis. However, its oral administration is associated with low bioavailability and gastroesophageal irritation. This work aimed at developing tablets containing sodium alendronate-loaded microparticles by direct compression to achieve a safe and effective form. The parameters evaluated were average weight, hardness, thickness and drug content.;In vitro; release tests were carried out using simulated gastric and intestinal fluids, and the profiles were analyzed through the Korsmeyer-Peppas mono- or biexponential dependent approaches. Tablets presented adequate average weight, thickness, good mechanical properties and drug content close to 100%. Moreover, the formulation released less than 11% of sodium alendronate in gastric fluid, exhibiting a good gastroresistance. At pH 6.8, almost 100% of the drug was released in 12h, showing a prolonged profile. The mathematical modeling indicated that the experimental data was better fitted to the biexponential equation. Furthermore, a good correlation coefficient was obtained for the Korsmeyer-Peppas model and the release exponent suggested that the drug dissolution was driven by anomalous transport. In conclusion, the microparticulated tablets can be considered a promising alternative for oral delivery of sodium alendronate.;O alendronato de sódio é um fármaco da classe dos bisfosfonatos, comumente utilizado no tratamento da osteoporose pós-menopausa. Entretanto, sua administração oral está associada à baixa biodisponibilidade e irritação gastroesofágica. Este trabalho objetivou o desenvolvimento de comprimidos contendo micropartículas de alendronato de sódio por compressão direta, a fim de obter uma forma segura e eficaz. Os parâmetros avaliados foram peso médio, dureza, espessura e teor de fármaco. Estudos de liberação ;in vitro; foram realizados utilizando fluído gástrico e intestinal simulado e o perfil de liberação foi analisado pelos modelos matemáticos de Korsmeyer-Peppas, mono- e biexponencial. Os comprimidos apresentaram peso médio adequado, espessura, dureza e teor próximo a 100%. Além disso, a formulação liberou menos de 11% do fármaco em fluído gástrico, mostrando uma boa gastrorresistência. Em pH 6,8, em torno de 100% do fármaco foram liberados em 12 h, apresentando liberação prolongada. A modelagem matemática indica que os resultados seguem a equação biexponencial. Pela análise do expoente de liberação obtido no modelo de Korsmeyer-Peppas sugere-se que a dissolução do fármaco ocorre por transporte anômalo. Concluindo, a preparação dos comprimidos microparticulados pode ser considerada uma alternativa promissora para a liberação oral do alendronato de sódio.

A simple RP-HPLC method for the determination of clotrimazole from acrylic nanocapsule suspensions

A simple and fast HPLC method has been validated for the determination of clotrimazole in nanocapsule suspensions prepared from an acrylic polymer, Eudragit RS100®. Chromatographic runs were performed on a RP C18 column with a mobile phase comprising methanol and water (90:10, v/v) at a flow rate of 1.0 mL/min with UV detection at 229 nm. The method was shown to be specific, linear (r = 0.9987), precise and accurate in a concentration range of 2.0-10.0 μg/mL. The proposed method can be successfully used to quantify clotrimazole content in acrylic nanocapsule formulations, as well as to estimate drug encapsulation efficiency.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Nanostructured Systems Containing Rutin: In Vitro Antioxidant Activity and Photostability Studies

The improvement of the rutin photostability and its prolonged in vitro antioxidant activity were studied by means of its association with nanostructured aqueous dispersions. Rutin-loaded nanocapsules and rutin-loaded nanoemulsion showed mean particle size of 124.30 ± 2.06 and 124.17 ± 1.79, respectively, polydispersity index below 0.20, negative zeta potential, and encapsulation efficiency close to 100%. The in vitro antioxidant activity was evaluated by the formation of free radical ·OH after the exposure of hydrogen peroxide to a UV irradiation system. Rutin-loaded nanostructures showed lower rutin decay rates [(6.1 ± 0.6) 10−3 and (5.1 ± 0.4) 10−3 for nanocapsules and nanoemulsion, respectively] compared to the ethanolic solution [(35.0 ± 3.7) 10−3 min−1] and exposed solution [(40.1 ± 1.7) 10−3 min−1] as well as compared to exposed nanostructured dispersions [(19.5 ± 0.5) 10−3 and (26.6 ± 2.6) 10−3, for nanocapsules and nanoemulsion, respectively]. The presence of the polymeric layer in nanocapsules was fundamental to obtain a prolonged antioxidant activity, even if the mathematical modeling of the in vitro release profiles showed high adsorption of rutin to the particle/droplet surface for both formulations. Rutin-loaded nanostructures represent alternatives to the development of innovative nanomedicines