DISSOLUTION AND ABSORPTION OF NIFEDIPINE IN POLYETHYLENE-GLYCOL SOLID DISPERSION CONTAINING PHOSPHATIDYLCHOLINE

The in vitro dissolution and in vivo absorption of solid dispersions of nifedipine-polyethylene glycol (nifedipine-PEG) and nifedipine-phosphatidylcholine-polyethylene glycol (nifedipine-PC-PEG) were investigated. The X-ray diffraction patterns and DSC thermograms showed that up to a ratio of 5:95 of nifedipine-PEG, the nifedipine was dispersed homogeneously in an amorphous state or dissolved in the solid dispersions. The incorporation of 5% PC into the nifedipine-PEG solid dispersion demonstrated no change in the solid-state characteristics of nifedipine as in the nifedipine-PEG solid dispersion. The dissolution of nifedipine from the solid dispersions was markedly enhanced as compared with the pure drug. The incorporation of PC into the nifedipine-PEG solid dispersion resulted in a 2.6- and 2.2-fold increase in nifedipine initial dissolution rate and dissolution after 60 min, respectively. This was attributed to the formation of lipid vesicles which entrapped a certain concentration of nifedipine during dissolution. The area under the curve after oral administration of the nifedipine-PC-PEG solid dispersion was 3.4-fold greater than that of the nifedipine-PEG solid dispersion.