Polyanhydrides processing techniques

In addition to polyesters, other types of biodegradable polymers such as polyurethanes, polyanhydrides, poly(amino acids), poly(vinyl alcohol), and poly(ester amide), are generally processable by conventional processing techniques for plastics. Their physical properties can be expected to be comparable, and sometimes can be used to supplement biodegradable polyesters. Although these polymers are more likely used in niche applications or incorporated with other polymers by making composite materials, they obviously provide more material choices in the design and manufacture of various biomedical products. 

The overall science around polyanhydrides is summarised in Figure 5.1. The main focus of this chapter is to introduce and provide an extensive review of the various promising aspects of one specific class of synthetic biodegradable medical polymer — poly anhydride. In the first part of the chapter the classification, chemical stmctures, and synthesis methods of various polyanhydrides are discussed. This is followed by a discussion of the in vitro and in vivo behaviour and degradation mechanism of these materials. Also, the various processing techniques that are employed are introduced and explained. Finally, medical applications of polyanhydride systems are presented, highlighting their role and their potential to be used as a family of medical polymers of the future generation . 

Several approaches for producing polyanhydride microspheres were developed. One was a hot-melt technique. This process yielded spherical microspheres, and the capsule yield was almost quantitative. The release of acid orange and insulin from PCPP-SA was studied. This approach is most useful for molecules that are exposed to the polymer melting temperature (76°C) without inactivation (26). 

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