Bioavailability and stability of nifedipine-enteric coating agent solid dispersion.

The absorption behavior and stability of nifedipine-enteric coating agent solid dispersions were studied using hydroxypropylmethylcellulosephthalate (HP-55) and methacrylic acid-methacrylic acid methyl ester copolymer (Eudragit L) as carriers. In the rat in situ absorption study, the dissolution behavior of HP-55 solid dispersion in the gastrointestinal tract was confirmed to be pH-dependent. After oral administration of these solid dispersions in beagle dog, area under the blood concentration curve (AUC) values were equivalent to that of polyvinylpyrrolidone solid dispersion, which showed remarkably improved dissolution behavior and bioavailability as compared with nifedipine alone. These systems were stable chemically and physically at 40 C and 40 C/80% R. H. during 6 months, and could be useful sustained absorption dosage forms with good bioavailability.