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ABSTRACT: The aim of the present paper was the use of mesoporous silicate MCM-41 to increase the dissolution rate of piroxicam, a non-steroidal anti-inflammatory drug-class II of the Biopharmaceutic Classification System. The inclusion/adsorption compound of piroxicam in MCM-41 was obtained with a drug loading of about 14%. X-ray powder diffraction and differential scanning calorimetry (DSC) revealed the presence of piroxicam not arranged in crystalline form and FT-IR spectroscopy showed the presence of light interactions (hydrogen bonds) between the silicate silanols and the drug. The decrease of Brunauer, Emmett and Teller (B.E.T.) specific surface area and pore volume between free MCM-41 and the inclusion/adsorption compound was a prove of the presence of piroxicam inside the mesopores. The inclusion compound was submitted to in vitro dissolution tests and a remarkable dissolution rate improvement was observed in comparison to the crystalline drug in all tested conditions. The dissolution profile at pH 1.2 was comparable to that of the marketed product Brexin, a formulation with rapid analgesic effect onset. The improvement of dissolution rate is due to both the lack of drug in the crystalline form and to the extremely large surface area of the siliceous support. Physical stability tests of the free drug and the inclusion/adsorption complex were conducted as well over one month storage at 40 degrees C at different relative humidity.
European Journal of Pharmaceutical Sciences 12/2007; 32(3):216-22. · 3.21 Impact Factor
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ABSTRACT: Nuclear DNA amounts were measured by Feulgen cytophotometry in Sorghum bicolor cv. 610 plants early exposed to 150 mM NaCl, a treatment known to induce an increased tolerance to salinity in plants carrying this genotype. In salt-treated plants, the percentages of 8C, 16C, and 32C nuclei in roots in the primary state of growth were 21.9%, 13.3%, and 4.3%, respectively. By contrast, in nonsalinized plants, only 3.5% of the nuclei had an 8C content and no higher DNA contents were observed. The salt treatment induced chromosome endoreduplication during the differentiation of cells in the root cortex, where 41.2% of the cells displayed a DNA content higher than 4C (versus 1.3% in control plants). No enhancement of endopolyploidy was observed in cells of the root vascular cylinder or the leaves of the salt-treated plants. In another S. bicolor genotype (DK 34-Alabama), noncompetent for salt adaptation, the same NaCl treatment did not induce chromosome endoreduplication in root cortex cells. Endopolyploidy may be considered as a part of the adaptive response of S. bicolor competent genotypes to salinity.
Protoplasma 06/2006; 227(2-4):113-8. · 1.92 Impact Factor
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ABSTRACT: Layered zirconium hydrogen phosphate, exfoliated by intercalation of propylamine and then exchanged with alkali metal ions has proved to be an excellent catalyst for Michael addition of -dicarbonyl compounds. The reactions occur with high yield, in mild conditions and with ease of work up. The catalyst, recovered from the reaction vessel, may be reused several times.
Catalysis Letters 01/1993; 22(4):333-336. · 2.24 Impact Factor
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ABSTRACT: The paper reports a new property of MCM-41 mesoporous materials, that is the improvement of the apparent solubility and the dissolution rate of water poorly soluble compounds. The indole-3-butyric acid (IBA), a plant growth regulator, was used as a model poorly soluble compound. The inclusion compound MCM-41-IBA was prepared and the final percent loading resulted 30%. The complex, analyzed by FT-IR, revealed the presence of hydrogen bonds between IBA and MCM-41 silanols, while XR diffraction and differential scanning calorimetry (DSC) demonstrated that the adsorbed IBA was in an amorphous form. This observation paralleled the in vitro release tests that showed for the adsorbed IBA a higher dissolution rate if compared to its crystalline form. In fact, IBA when is included on MCM-41 had twice the solubility of free IBA in water.Then new IBA features when included in the complex revealed to be very interesting for practical purposes, since its effect, as plant growth hormone, is limited by the low solubility. In fact the aqueous dispersion of MCM-41-IBA (500 ppm of IBA) resulted very useful to increase the rooting ability of Olea europaea L. cultivar Leccino, cuttings.
Microporous and Mesoporous Materials 96:177-183. · 3.29 Impact Factor
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ABSTRACT: A microporous material obtained from kanemite, a layered polysilicate, was studied in order to investigate its feasibility of including drugs and then releasing them. Diphenydramine hydrochloride was chosen as a model drug. The preparation of the microporous material and its loading with the drug are described. As kanemite is able to intercalate anions between its layers, the intercalation compound of diphenydramine and kanemite was also prepared. Both the drug-loaded microporous material and the intercalation compound were submitted to dissolution tests at pH 7.5. The drug release profiles from these two different materials and from a physical mixture were compared.
Il Farmaco 56(5-7):421-5.
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ABSTRACT: The mesoporous silicate MCM-41 was studied for its properties to adsorb and to influence the photostability and the release of three organic ultraviolet (UV) ray absorbents, namely benzophenone-3 (B3), benzophenone-2 (B2) and p-aminobenzoic acid (PABA). MCM-41 microcrystals have been loaded with the UV absorbents obtaining a good loading w/w percentage. The loaded samples have been characterized by chemical and thermal analyses, X-ray diffraction, N2 adsorption isotherms. Photochemical studies demonstrated that the UV-shielding properties of B2 were maintained whereas in other cases a small reduction of sunscreen protection range was noticed. B3 and B2 release from loaded MCM-41 formulations were studied and compared to those obtained from formulations containing free UV ray absorbent; no remarkable differences were observed in the release profiles.
Journal of Physics and Chemistry of Solids.
