Abstract:
Controlled release of nifedipine from combined carriers namely, Eudragit RS 100, Eudragit RL 100 and povidone K30 were attained by spray drying technique. The drug-combined carriers ratio of 1:10 with the mixing ratios of nifedipine:Eudragit RS 100 or Eudragit RL 100:PVP K30 as 1:10:0, 1:8:2, 1:5:5, 1:2:8 and 1:0:10 were investigated. The effects of inlet air temperature, the spray concentration, types and the ratios of combined carriers on physicochemical properties of the spray dried powders and on the release characteristics of the resultant microspheres were investigated. As shown by the powder X-ray diffraction patterns, differential scanning calorimetric thermograms, nifedipine was consistently transformed from to amorphous form in the polymer matrices. The fourier transform infrared spectra demonstrated intermolecular interaction between nifedipine and the polymers in the microspheres. The kinetics of nifedipine release from microspheres were evidenced to follow the higuchi diffusion-controlled mechanism. The dissolution characteristics of nifedipine microspheres were evaluated in the terms of dissolution efficiency and higuchi rate constant. It was found that PVP K30 content controlled the drug release from eudragit insoluble matrix. Low inlet temperature, high spray concentration and more hydrophilic Eucragit RL100 were promoting factors for higher dissolution efficiency and release rate constant.
