Polyanhydrides with hydrophobic terminals

Polyanhydrides prepared from hydrophobic diacids such as sebacic acid (SA) are brittle and unstable in storage and degrade with time. The physical properties of these polyanhydrides have been improved by introducing hydrophobic terminals into the main chain which has provided better stability and controlled the molecular weight. The effects of molecular weight, pliability, biodegradation and drug release on polymer were investigated. Poly(sebacic anhydride) (PSA) was terminated with the unsaturated fatty acids, ricinoleic acid, oleic acid, linoleic acid and the cholesterol derivative, lithocholic acid, and prepared in the weight ratio of 70:30. Polymers thus obtained had a predictable molecular weight of 3-8 x 10(3) and an M-p of 60-76degreesC and degraded at the rate of 3.3-7.6 mg/cm(2)/day. The rate of degradation was dependent on the contents of the hydrophobic terminals. These polyanhydrides were found to be useful for the release of hydrophobic and hydrophilic drugs for 2-3 weeks in vitro. Copyright (C) 2003 John Wiley Sons, Ltd.