Abstract
Thermal stability of alendronate sodium in a mixture with cross-linked acrylic acid polimers and chitosan, formulated and preparated as oral matrix systems, was qualitatively evaluated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and infrared spectroscopy (FT-IR). The results of the study have shown alendronate stability in association with carbopol and chitosan. DTG curves and FT-IR results suggest certain interactions between carbopol and chitosan, most probably ionic and hydrogen bonds. We consider that the nature and intensity of these bonds could be a positive factor decreasing pH dependence of Carbopol in releasing drug substance. Keywords: alendronate, carbopol, chitosan, thermal analysis