Synthesis and characterization of acrylic type hydrogels containing azo derivatives of 5-amino salicylic acid for colon-specific drug delivery

Abstract

pH-sensitive hydrogels are suitable candidates for oral delivery of therapeutic peptides, proteins and drugs, due to their ability to respond to environmental pH changes. Terephthalic acid was covalently linked with 2-hydroxyethyl methacrylate (HEMA), abbreviated as cross-linking agent (CA). Acryloyl ester of 5-[4-(hydroxy phenyl) azo] salicylic acid (HPAS) as an azo derivative of 5-amino salicylic acid (5-ASA) was prepared under mild conditions. The HPAS was covalently linked with acryloyl chloride, abbreviated as APAS. Free radical cross-linking copolymerization of polymerizable azo derivative of 5-ASA (APAS) and methacrylic acid (MAA) in two different molar ratios, with the various ratios CA as cross-linking agent were carried out with using 2, 2'-azobisisobutyronitrile (AIBN) as initiator at the temperature range 60-70 degrees C. The composition of the cross-linked three-dimensional polymers was determined by FTIR spectroscopy. Glass transition temperature (Tg) of the network polymers was determined calorimetrically. The hydrolysis of drug-polymer conjugates was carried out in cellophane membrane dialysis bags containing aqueous buffer solutions (pH 7.4 and pH 1) at 37 degrees C. The effect of copolymer composition on the hydrolytic degradation was studied in simulated gastric fluid (SGF, pH 1) and simulated intestinal fluid (SIF, pH 7.4) at 37 degrees C. Monitoring of the hydrolysis process by HPLC and UV spectroscopy shows that the azo prodrug (HPAS) was released by hydrolysis of the ester bond located between the HPAS and the polymer chain. The drug-release profiles indicate that amount drug release dependent on the content of MAA groups and crosslinking.

Biodegradable Hydrogels Based on Alginate For Control Drug Delivery Systems

“…This sharp swelling-deswelling behavior of the hydrogels makes them suitable candidates for controlled drug delivery systems. Such on-off switching behavior as reversible swelling and deswelling has been reported for other ionic hydrogels [11][12] .…”

“…1(b)) shows a new characteristic absorption band at 1680 cm -1 verifying the formation of alginate-g-PAAm. This peak attributed to C=O stretching in carboxamide functional groups of PAAm [12][13] . The stretching band of -NH overlapped with the OH stretching band of the alginate portion of the copolymer…”

New Polymeric Hydrogel Formulations based on Poly(vinyl alcohol) for the Controlled Release of Bovine Serum Albumin

“…As can be seen from the figure, an increase in drug concentration in the swelling medium increased the amount of adsorbed drug, as observed in many adsorption studies [11][12][13] .…”

Alginate‐based biodegradable superabsorbents as candidates for diclofenac sodium delivery systems

“…Drug delivery to the colon has implications in a number of therapeutic areas, particularly in the treatment of colonic diseases such as ulcerative colitis and Chron's disease and in the oral delivery of peptides and other drugs degraded in the upper gastrointestinal tracts 5, 6. To study potential application of alginate based superabsorbent containing DS as a pharmaceutically active compound, we have studied the drug releases behavior of the polymers under physiological conditions.…”

“…These hydrogels are suitable candidate for drug delivery system (DDS). Intelligent drug carriers release the right amount of drug at the right time and/or at the right place may enable us to precisely control the delivery of drugs 3–6. The degree of swelling and dimensions of the superabsorbents can affect and control the release rate of drug.…”