Supercritical CO2 adsorption of non-steroidal anti-inflammatory drugs into biopolymer aerogels

Supercritical carbon dioxide adsorption was applied to incorporate three non-steroidal anti-inflammatory drugs (NSAIDs), namely nimesulide (NIM), ketoprofen (KET) and diclofenac sodium (DIC), into maize starch aerogel (MSA) and calcium alginate aerogel (CAA). The obtained composites can be used to develop tablets with a fast or controlled release of the active principle, depending on the chosen aerogel. Adsorption kinetics and isotherms were determined at 18 MPa and 40 and 60 degrees C to study the effect of temperature. Adsorption kinetics demonstrated for all compounds that drug loadings were higher using CAA as a support than MSA. Indeed, the maximum loadings were obtained at 60 degrees C and were equal to 0.13, 1.64 and 3.43 mmol(drug)/g(cAA )for NIM, KET and DIC, respectively. The produced composite systems were characterized by various techniques, such as scanning electron microscopy, differential scanning calorimetry, X-ray microanalysis, FT-IR and UV-vis spectroscopy. Dissolution tests revealed that the adsorption into MSA allowed a faster release of the NSAIDs than pure crystalline drugs, whereas CAA promoted a controlled release of the NSAIDs. For example, the dissolution rate of NIM, if compared with the one of the unprocessed drug, is 1.5 times faster when adsorbed into MSA and 4.6 times slower if adsorbed into CAA. Moreover, Peppas mathematical model was applied to identify the dominant factor in the drug release behavior.