Studies on the development of intragastric floating and sustained release preparation. I. Application of calcium silicate as a floating carrier

Abstract

We prepared an intragastric floating preparation using porous calcium silicate (Florite® RE, FLR) as a floating carrier, which has floating ability due to the air included in the pores when they are covered with a polymer, it also has a sustained drug release property. Floating granules were prepared by dropping a 5 or 10% (w/v) ethanol solution of hydroxypropylcellulose (HPC) and ethylcellulose (EC) in 4 different concentration ratios while the FLR was being agitated in a beaker. After the mixture was dried in vacuo and sieved, we regarded the granules obtained as primary coated granules (PCG). After drying, the ethanol solution of the polymer was dropped and dried in vacuo again, and sieving was carried out to obtain secondary coated granules (SCG). The floating property and surface and inner structures of PCG and SCG were studied. Further, we prepared PCG and SCG including diclofenac sodium (DS) (DS-PCG, DS-SCG) as a model drug, and the drug release profile from these granules was observed. The floating property of SCG was better than that of PCG. A longer floating time was observed with a higher polymer concentration and a lower HPC composition ratio. It was observed by a scanning electron microscope (SEM) and the pore size distribution that more pores of FLR in SCG were covered with polymer than those in PCG. DS-SCG showed a smaller release rate than DS-PCG. These results suggest that FLR is a useful floating carrier for the development of floating and sustained release preparations.