Formulation and Evaluation of Smart Polymeric Systems for Controlled Release of Antihypertensive Drugs

Abstract

In the first investigation covalently crosslinked smart polymeric system of hydrogel based on poly vinyl alcohol (PVA) and methacrylic acid (MA) was designed by free radical polymerization with different compositions using glyoxal (40 % water solution) as crosslinker. It was observed that swelling of hydrogel had a pronounced enhancing effect on increasing the concentration of MA due to availability of more ionized carboxylic groups of MA but produced an opposite effect on increasing the concentration of glyoxal owing to less porous structure. As far as PVA is concerned, swelling did not show significant effect on increasing the concentration of PVA. Hydrophilic polymer PVA rich in hydroxyl group pertained to be highly interactive with water. It was examined that the release of metoprolol tartrate decreased with increased concentration of glyoxal, but increased with increase in concentration of MA. PVA/MA hydrogel was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) to study the structure and crystallinity of hydrogel respectively. Morphology was studied through scanning electron microscopy (SEM). Furthermore differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were also performed to characterize thermal stability. It may be concluded that the mechanism of drug release was mainly non-Fickian diffusion. The second investigation enlightened a robust design to develop biodegradable pH responsive hydrogel of carrageenan (CA) / methacrylic acid (MA) and to evaluate the potential of formulations to sustain the release of perindopril. Glyoxal crosslinked carrageenan graft methacrylic acid (CA-g-MA) macromolecule formulations were fabricated in the presence of potassium persulphate as free radical initiator system. Crosslinker composition was varied in JA1, JA2 and JA3 formulations, while JA4, JA5 xx and JA6 had variable MA concentrations respectively. JA7, JA8 and JA9 had variable CA concentrations. Preliminary experiments on swelling ratio, drug loading and drug release were carried out to investigate the ability of CA-g-MA formulations as controlled drug delivery system. Release of drug was dependent on monomeric composition, crosslinker and pH of release media. The morphology, structure, swelling capacity, interpenetrating polymeric networking parameters and thermal stability were evaluated. The results obtained indicated that the modulated formulations have considerable potential as drug-carrier materials for controlled delivery system.