Web Release Date: August 25,
Synthesis and Characterization of PEG-Based Ether-Anhydride Terpolymers: Novel Polymers for Controlled Drug Delivery
Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, Maryland 21218
Received January 21, 2004
Revised Manuscript Received July 1, 2004
Abstract:
A series of biodegradable poly(ether-anhydrides) composed of poly(ethylene glycol) (PEG),
sebacic acid (SA), and 1,3-bis(carboxyphenoxy)propane (CPP) were synthesized for use in advanced drug
delivery applications. PEG (Mn = 8000 Da) was incorporated to reduce polymeric particle clearance rates
by the immune system and improve particle resuspension and aerosolization efficiencies. CPP and SA
were selected to render the polymer insoluble in water and allow control over polymer degradation and
drug release rates. In particular, CPP incorporation caused a significant decrease in polymer degradation
rates and release kinetics of model drugs incorporated into poly(ether-anhydride) microparticles.
Terpolymers were synthesized with weight-average molecular weights over 65 kDa without catalyst. The
first thermal transition in polymers containing 
10 wt % PEG was ~80 
C (well above typical storage
conditions and body temperature), and there was no evidence of a glass transition (-100 to 200 C).
Several of the polymers were used to produce particles suitable for injection or inhalation; these particles
released model drugs, with molecular weights ranging from 443 to 5 143 000 Da, in a continuous fashion
for up to 7 days.
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