21 resultados para Lipid nanoparticles

em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"


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Solid lipid nanoparticles (SLNs), loaded and unloaded with praziquantel (PRZ-load SLN and PRZ-unload SLN) were prepared by two different procedures: (a) oil-in-water hot microemulsion method, obtaining at 70 degrees C an optically transparent blend composed of surfactant, co-surfactant, and water; and (b) oil-in-water microemulsion method, dissolving the lipid in an immiscible organic solvent, emulsified in water containing surfactants and co-surfactant, and then evaporated under reduced pressure at 50 degrees C. The mean diameter, polydispersity index (PdI), and zeta potential were 187 to 665 nm, 0.300 to 0.655, and -25 to -28 mV respectively, depending on the preparation method. The components, binary mixture, SLNs loaded and unloaded with PRZ, and physical mixture were evaluated by differential scanning calorimetry (DSC) and thermogravimetry (TG). The non-isothermal isoconversional Flynn-Wall-Ozawa method was used to determine the kinetic parameters associated with the thermal decomposition of the samples. The experimental data indicated a linear relationship between the apparent activation energy E and the pre-exponential factor A, also called the kinetic compensation effect (KCE), allowing us to determine the stability with respect to the preparation method. Loading with PRZ increased the thermal stability of the SLNs.

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Praziquantel (PZQ) is a pyrazinoisoquinoline anthelmintic that was discovered in 1972 by Bayer Germany. Currently, due to its efficacy, PZQ is the drug of choice against all species of Schistosoma. Although widely used, PZQ exhibits low and erratic bioavailability because of its poor water solubility. Nanostructured lipid carriers (NLC), second-generation solid lipid nanoparticles, were developed in the 1990s to improve the bioavailability of poorly water soluble drugs. The aim of this study was to investigate nanostructured lipid carriers as a strategy to improve the efficacy. of PZQ in S. mansoni treatment. We prepared NLC2 and NLC4 by adding seventy percent glycerol monostearate (GMS) as the solid lipid, 30% oleic acid (OA) as the liquid lipid and two surfactant systems containing either soybean phosphatidylcholine/poloxamer (PC/P-407) or phosphatidylcholine/Tween 60 (PC/T60), respectively. The carriers were characterized by nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis and Fourier transform-infrared spectroscopy. The safety profile was evaluated using red cell hemolysis and in vitro cytotoxicity assays. The results showed that the encapsulation of PZQ in NLC2 or NLC4 improved the safety profile of the drug. Treatment efficacy was evaluated on the S. mansoni BH strain. PZQ-NLC2 and PZQ-NLC4 demonstrated an improved efficacy in comparison with free PZQ. The results showed that the intestinal transport of free PZQ and PZQ-NLC2 was similar. However, we observed that the concentration of PZQ absorbed was smaller when PZQ was loaded in NLC4. The difference between the amounts of absorbed PZQ could indicate that the presence of T60 in the nanoparticles (NLC4) increased the rigid lipid matrix, prolonging release of the drug. Both systems showed considerable in vitro activity against S. mansoni, suggesting that these systems may be a promising platform for the administration of PZQ for treating schistosomiasis.

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Lung cancer is a leading cause of death in developed countries. Although smoking cessation is a primary strategy for preventing lung cancer, former smokers remain at high risk of cancer. Accordingly, there is a need to increase the efficacy of lung cancer prevention. Poor bioavailability is the main factor limiting the efficacy of chemopreventive agents. The aim of this study was to increase the efficacy of cancer chemopreventive agents by using lipid nanoparticles (NPs) as a carrier. This study evaluated the ability of lipid NPs to modify the pharmacodynamics of chemopreventive agents including N-acetyl-L-cysteine, phenethyl isothiocyanate and resveratrol (RES). The chemopreventive efficacy of these drugs was determined by evaluating their abilities to counteract cytotoxic damage (DNA fragmentation) induced by cigarette smoke condensate (CSC) and to activate protective apoptosis (annexin-V cytofluorimetric staining) in bronchial epithelial cells both in vitro and in ex vivo experiment in mice. NPs decreased the toxicity of RES and increased its ability to counteract CSC cytotoxicity. NPs significantly increased the ability of phenethyl isothiocyanate to attenuate CSC-induced DNA fragmentation at the highest tested dose. In contrast, this potentiating effect was observed at all tested doses of RES, NPs dramatically increasing RES-induced apoptosis in CSC-treated cells. These results provide evidence that NPs are highly effective at increasing the efficacy of lipophilic drugs (RES) but are not effective towards hydrophilic agents (N-acetyl-L-cysteine), which already possess remarkable bioavailability. Intermediate effects were observed for phenethyl isothiocyanate. These findings are relevant to the identification of cancer chemopreventive agents that would benefit from lipid NP delivery.

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