Page 47 - controlled drug delievery

4- Bioerodible/Biodegradable Systems.

• Bioerodible polymer: erode without degradation i.e. without changes in
the chemical structure.

• Biodegradable polymer: erode with degradation by chemical (water) or
biological (enzymes) reaction. Degradation might precede significant
erosion.

• These matrices can combine diffusion and dissolution of both the matrix
and the drug.

• Complex release kinetics that are difficult to control.
• Rate limiting step is the polymer erosion-degradation rate.