Abstract
In order to develop preparations of nifedipine with good bioavailability and stability, especially in relation to humidity, various fine granules were prepared by coating lactose surfaces with a dispersion system of nifedipine and water-soluble polymer. The system using polyvinylpyrrolidone (PVP) or hydroxypropylmethylcellulose (HPMC) showed good dissolution properties and bioavailability of nifedipine. It was found that nifedipine in these preparations was chemically stable for 3 months at 75% relative humidity and 40°C. An X-ray diffraction study suggested that nifedipine was present in its amorphous form in the preparations using HPMC or PVP. Amorphous nifedipine in fine granules using HPMC was found to be stable under humid conditions, although crystallization occurred in the granules using PVP. The fine granules using HPMC and PVP both showed good bioavailabilities after oral administrations in dogs, and no significant difference was observed in bioavailability parameters between the fine granules using HPMC and PVP. Preparation of fine granules using HPMC may be a useful means to improve the bioavailabilities and stabilities of poorly water-soluble drugs.
