Synthesis and evaluation of new linear azo-polymers for colonic targeting

Abstract

The polyurethanes and polyetherurethanes containing 5-[4-(hydroxyl phenyl)azo] salicylic acid (HPAS) and 4,4′-dihydroxyazobenzene (DHAB) in the main chain were prepared by reacting 1,6-hexamethylenediisocyanate (HDI) with HPAS and DHAB and evaluated as materials for colonic targeting. The polyetherurethanes were prepared by reacting poly (ethylene glycol) with an excess of HDI to obtain a prepolymer, which were reacted with HPAS and DHAB low molecular weight diol. The structure of the polymers was confirmed by FT-IR and ¹H-NMR spectroscopy. The hydrolysis of the polymers was carried out in dialysis bags containing aqueous buffer solution (pH 1 and pH 7.4) at 37°C. UV spectroscopy was used to show that HPAS and DHAB were released by hydrolysis of the urethane bond. The polyurethane drug conjugates have longer duration of activity, due to slow release of HPAS and DHAB.

Keywords:

• COLON-SPECIFIC DELIVERY
• BIODEGRADABLE
• POLYMERIC PRODRUG
• TARGETING