Abstract
Segmented polyurethanes containing azo aromatic groups in the main chain were synthesized by reaction of 3,3′-azobis(6-hydroxybenzoic acid) (ABHB), 5-[4-(hydroxyphenyl)azo] salicylic acid (HPAS), and 5-[1-hydroxynaphthyl)azo] salicylic acid (HNAS) with hexamethylenediisocyanate (HDI). All synthesized monomers and polymers were characterized by elemental analysis, FTIR, 1H-NMR spectra, TGA and DSC analysis. All the synthesized azo polymers showed good thermal stability and the onset decomposition temperature of all these polymers was found to be above 195 °C under nitrogen atmosphere. The release of 5-ASA under physiological conditions (pH = 7.8 and pH = 1.5) was investigated at body temperature (37 °C). The release rate of 5-ASA increased with increasing pH (i.e., 7.8 > 1.5).
Highlights
The colon has recently received great attention as a potential site for the delivery of pharmaceutical moieties
The resulting biodegradable polyurethanes containing 5-aminosalicylic acid (5-ASA) in the main chain were used as polymeric prodrug systems
A new system of biodegradable polymers including azo polymers was synthesized to optimize the therapeutic properties of the drugs and render them safer and more effective
Summary
The colon has recently received great attention as a potential site for the delivery of pharmaceutical moieties. The successful delivery of drugs to the colon via the gastrointestinal (GI) tract requires the protection of a drug from being released in the stomach and small intestine. The generation of the active moiety, 5-aminosalicylic acid (5-ASA), by the action of the intestinal microflora has been the key for colon-specific drug delivery to the large intestine based upon the enzymatic reduction of the azo bond [13]. In this study, segmented polyurethanes containing azo aromatic groups in the main chain were synthesized by reaction of 3,3'-azobis(6-hydroxybenzoic acid) (ABHB), 5-[4-(hydroxyphenyl)azo]. The resulting biodegradable polyurethanes containing 5-aminosalicylic acid (5-ASA) in the main chain were used as polymeric prodrug systems. The use of these prodrug systems can protect 5-ASA during its transfer to the colon.
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