Polyanhydrides erosion rate constants

Erosion Rate Constants for many Common Polyanhydrides... 

Polyanhydrides with Erosion rate constant Number-average Reference... 

Figure 8.36 Theoretical representation of a polymer matrix changes during erosion (dark pixels = nondegraded areas, white pixels = degraded areas), where (a rate constant) = 2.7 x 1 0 s for a sample containing 50% polyanhydride CPP.

Polyanhydrides because of their surface erosion properties can be ideal materials for a constant rate release profile (a zero order). Furthermore, these polyanhydrides are very hydrophobic and their hydrolytic degradation may take relatively a long time, which is not suitable for pulsatile release. Hence, in order to achieve a tunable erosion kinetics, a two-component polyanhydride made of SA precursor and CPP precursor when copolymerized with polyethylene glycol (PEG) was found to retain the surface erosion of two-component polyanhydride while increasing the erosion rate due to inaeased hydrophilicity by PEG functionality. Relatively faster erosion rates can be achieved by adjusting PEG precursor content [37]. 

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