Abstract
Nifedipine-loaded polyacrylate microspheres were prepared using a solvent evaporation process. The analysis of the nifedipine release profiles as a function of the process variables revealed that the organic phase viscosity increase did not affect significantly the nifedipine release profile. In contrast, increasing the drug concentration decreased the release rate from the microspheres as a result of formation of nifedipine crystalline domains in the microspheres with increasing drug contents. It was found that all the global release profiles yielded by the nifedipine microspheres at low loading conformed with desorption kinetics of a dissolved drug from a monolithic spherical device. At intermediate and higher nifedipine payloads, it was not possible to identify any kinetic model. This is probably due to drug-polymer interactions that would account for the deviation of nifedipine release profile from the expected Higuchi diffusional model of dispersed drug particles in spherical micromatrices. Furthermore, these drug release profiles were quite similar to the dissolution profile of pure nifedipine crystals, suggesting that the drug release from the highly loaded microspheres is governed by the dissolution rate of the nifedipine crystalline domains in the microspheres.
Original language | English |
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Pages (from-to) | 213-222 |
Number of pages | 10 |
Journal | Journal of Controlled Release |
Volume | 12 |
Issue number | 3 |
DOIs | |
State | Published - May 1990 |
Keywords
- Eudragit polyacrylate
- microspheres
- nifedipine
- release kinetics