Poly(ortho esters): Recent developments for biomedical applications

Poly(ortho esters) (POE) are hydrophobic and bioerodible polymers that have been under development since the early 1970s. Up to now, four generations of such polymers have been described. Of most interest are poly(ortho esters) III and poly(ortho esters) IV. POE III is a semi-solid material that has been shown to be highly biocompatible and is currently being investigated as a carrier for sustained drug delivery to treat diseases of the posterior segment of the eye. However, the polymerization is difficult to control and is not readily scaled up. POE IV can be easily prepared in a highly reproducible manner, is very stable provided moisture is rigorously excluded and has also been shown to be biocompatible. It is currently under development for a variety of applications, such as ocular delivery, protein release, and periodontal disease treatment.