Polyanhydrides

Properties and Applications

Polyanhydrides are an important class of biodegradable polymers. They are highly susceptible to hydrolysis and degrade into non-toxic diacid monomers that can be metabolized and eliminated from the body, that is, many polyanhydrides are considered to be biocompatible and thus, are suitable materials for medical and pharmaceutical applications. Two common polyanhydrides are poly(sebacic anhydride) (PSAn) and poly(azelaic anhydride) (PAAn). However, these two anhydrides have found only limited uses due to their high crystallinity and rapid degradation. In order to reduce the crystallinity and degradation rate, they are typically copolymerized with aromatic anhydrides or aliphatic fatty acid dimers.

Polyanhydrides are almost exclusively used in the pharmaceutical and medical field. They are rather expensive when they are used alone. To lower cost and to improve their processing and end use properties, they are often blended with other resins such as starch. Important applications include controlled-release coatings for drug delivery systems¹ and temporary medical implants that decompose safely over time, and therefore, eliminate the need for a second surgical invention for removal.

Manufacturers

¹ Other important bio- and environmentally degradable polymers that are currently used or studied for controlled drug delivery include: poly(2-hydroxy ethyl methacrylate), poly(N-vinyl pyrrolidone), poly(methacrylate), poly(acryl amide), poly(acrylic acid), poly(vinyl alcohol), poly(L-lactide), poly(DL-lactide-co-glycolide), poly(ethylene-co-vinyl acetate), poly(ethylene glycol), poly(DL-lactide-co-ε-caprolactone), and poly(hydroxy alkanoate)s