Dissolution and Absorption of Nipedipine from Nifedipine-Polyvinylpyrrolidone Coprecipitate

Attempt was made to develop the solid dosage form of nifedipina which showed good absorption rate and total bioavailability. Nifedipine is a poorly water-saluble drug, whom bioavailability is low when administered orally in the crystalline form. Solutions of nifedipine were well absorbed from the gastrointestinal tract. The dissolution rate of PVP-nifedipine coprecipitates exhibited rapid dissolution rate. X-ray diffraction data suggested the lack of crystallinity in the coprecipitate. The relation between the dissolution rates and average molecular weights of PVP was studied. Nifedipine in the copretipitate was chemically stable to heat and humidity, but the dissolution rate of nifedipine from the coprecipitate stored at 21° and 75% R.H. markedly decreased. X-ray diffraction data revealed that it might be due to the transformation of amorphous form of nifedipine to crystalline form under higher relative humidity. The gastrointestinal absorption of nifedipine in beagle dogs after oral administration of the coprecipitate was increased than that after oral adniniatration of the physical mixture.