SUSTAINED-RELEASE FORMULATIONS FOR NIFEDIPINE

Three formulae of nifedipine sustained release granules were tried, each containing 10% of the drug. The former one was composed of nifedipine, lactose and PVP 40000, and prepared adopting moist granulation technique. In the second formula, the drug, PEG 6000 and HMPC were coprecipitated into microcrystalline cellulose. While the latter one was composed of nifedipine, and three components which are; HMPC; ethyl cellulose as binders; and corn starch as a filler. These granules and the plain nifedipine powder were investigated in vitro as well as in healthy subjects. The third formula showed pronounced dissolution rate compared to the other tested ones. The granules of the second and the third formulae were administered orally to healthy subjects and the plasma levels of nifedipine were compared with those after administration of nifedipine powder. Plasma levels following the administration of the granules were prolonged but a reduced level was observed. This indicates the sustained release of the drug from the granules in vivo. The plasma profiles of nifedipine indicated that the latter formula granules were superior to that with the second formula granules with respect to prolonging the effective plasma levels and to minimizing the intersubject variations.