How are polyanhydrides degraded?

Polyanhydrides are a class of biodegradable polymers characterized by anhydride bonds that connect repeat units of the polymer backbone chain. In vivo, polyanhydrides degrade into non-toxic diacid monomers that can be metabolized and eliminated from the body.

How to make polyanhydride?

Polyanhydrides are mainly prepared by melt condensation of dicarboxylic acid with an acetic anhydride at a high temperature under vacuum. The most widely studied polyanhydrides are based on sebacic acid, adipic acid, and terephthalic acid. The anhydride bonds hydrolytically cleave and form water-soluble products.

How is Polyanhydride synthesized?

Polyanhydride polymers are synthesized by dehydrating dicarboxylic acid functional monomers to form corresponding polyanhydride linkages (Figure 7). The anhydride groups in the polymer chain are very moisture sensitive and on contact with water rapidly hydrolyze to form carboxylic acid groups.

Is anhydride a functional group?

Anhydride (acid anhydride): A functional group characterized by two acyl groups joined by an oxygen atom.

How is the solubility of CPP affected by sebacic acid?

Sebacic acid created by degradation was shown to determine the pH inside pores, thereby limiting the solubility of CPP. Whenever sebacic acid has left the device, which according to Figure 6 is after approximately 8 days, the solubility of CPP increases tremendously, visible from the increase in release rate.

Which is fast to degrade PCCP or PSA?

The poly (sebacic anhydride) (pSA) is fast to degrade. Separately neither of these materials can be used, but if a copolymer is made in which 20% of the structure is pCCP and 80% is pSA, the overall properties meet the needs of the drug.

When does sebacic acid increase the degradation rate?

By extrapolation, 1 mm thick disks of PCPP will completely degrade in more than three years. The degradation rates were enhanced by copolymerization with sebacic acid. An increase of 800 times was observed when the sebacic acid concentration reached 80%.

When does an optically active substance undergo degradation?

RACEMIZATION  An optically active substance loses its optical activity without changing its chemical composition  In general, undergo degradation in accordance with first order kinetic principles 26 27.