Polyanhydrides implantable controlled drug delivery

In a recent US patent, Ziegast described a series of polyanhydrides (of the formula shown below) which are useful for controlled drug delivery of drugs [55]. These polymers have a similar structure to the polymers synthesized by Conix (Table 1) [11, 12], but with different chain structures between the two aromatic rings. The polymers were soluble in chlorinated hydrocarbons with a Tg ranging from 6 to about 90 °C. The in vitro degradation in phosphate buffer of these polymers is about 100 days with a lag time of up to 30 days for some polymers [55]. If these homopolymers are implanted in animals, they will produce large diacid monomers which have to be eliminated from the body. 

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