Improving the solubility of poorly water-soluble drugs remains an important challenge for the pharmaceutical industry. Usually, these drugs are mechanically mixed with porous silicate substrates (e.g. calcium silicate or kaolin) to enhance their dissolution rates. Our objective was to investigate the loading of poorly water-soluble drugs (e.g. ibuprofen and naproxen) onto a mesoporous silicate material and its amino-functionalized derivative; and to study the kinetics of the drug release in simulated body (SBF, pH = 7.4) and simulated gastric (SGF, pH = 1.2) fluids. Interactions between the drug carboxylic acid groups and the amine functions of the carrier are expected to modulate the drug release. A loading up to 300 mg of drug per gram of solid was achieved. FT-IR, powder XRD and TGA/DSC characterizations indicate that the drugs are loaded in their more soluble amorphous forms. The drug release profiles in SBF and SGF at 37?C were determined by monitoring the concentration of the drug in the release medium by UV spectrophotometry. The release rates of the drugs in SBF were found to be dependent of the morphology of the drug-loaded solid (i.e. fine powder, coarse powder or pellet), while no release of the drugs was observed in SGF.
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