Biodegradable Poly(Acetonide Gluconic Acid) for Controlled Drug Delivery

We
report here on the synthesis, characterization, degradation,
and drug release of acetal-protected gluconic acid-based poly­(α-hydroxy
ester). This polyester was synthesized by ring-opening polymerization
of O-carboxyanhydride of acetal-protected gluconic acid. The polymer
undergoes hydrolytic degradation under mild acidic media, whereas
minimal degradation takes place under physiological pH. Under acidic
conditions, the acetal-protecting groups are hydrolyzed, resulting
in a water-soluble polyester with saccharide side chains that erodes
from the surface, leaving the bulk of the polymer matrix intact. At
pH 3.5, zero-order kinetics was maintained for 50 days accounting
for ∼75% drug release. These biodegradable, pH-responsive,
sustained zero-order release kinetics of the polymer have application
as drug carriers for oral drug delivery or medical implants or also
for nonmedical applications.