Loading capacity and release property of piperine loaded silica aerogel and silica xerogel

Abstract

The feasibility of silica matrix as an oral drug delivery carrier for natural product was explored. Piperine was loaded into silica aerogel and xerogel via three different methods; impregnation, physical mixing and direct synthesis. Fourier-transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopies results strongly indicated that no detectable drug degradation had occurred during the loading procedure. Brunauer-Emmett-Teller surface analysis (BET), X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM) results indicated the successful loading of piperine into silica matrices. XRD results show the amorphization of piperine crystals after loading process with silica aerogel or xerogel, indicating the increment in the specific surface area of the drug. The degree of crystallinity of piperine loaded silica aerogel is extremely low compared to piperine-xerogel formulations. UV-Vis spectroscopy analysis revealed that the amount of piperine loaded was higher in silica aerogel than silica xerogel. This was due to the larger pore and higher surface area of silica aerogel compared to silica xerogel. Investigation on the release profile of piperine from loaded silica matrices in simulated gastric and intestinal fluids found that piperine loaded silica matrices dissolve faster than crystalline drug due to increase in specific surface area and non crystallinity state of the system. Piperine loaded silica aerogel gave the fastest dissolution (up to 100%), followed by piperine-xerogel (up to 45%) and crystalline piperine (< 5%). Formulations prepared via direct synthesis showed the fastest release, followed by impregnated and physically mixed systems. The ease in collapse of the silica matrices structure in water was observed to favor a faster release.