Release characteristics of diclofenac sodium from poly(vinyl alcohol)/sodium alginate and poly(vinyl alcohol)-grafted-poly(acrylamide)/sodium alginate blend beads

In this study, acrylamide (AAm) was grafted onto poly(vinyl alcohol) (PVA) with UV radiation at ambient temperature. The graft copolymer (PVA-g-PAAm) was characterized by using Fourier transform infrared spectroscopy (FTIR), elemental analysis and differential scanning calorimetry (DSC). Polymeric blend beads of PVA-g-PAAm and PVA with sodium alginate (NaAlg) were prepared by cross-linking with glutaraldehyde (GA) and used to deliver a model anti-inflammatory drug, diclofenac sodium (DS). Preparation condition of the beads was optimized by considering the percentage entrapment efficiency, particle size, swelling capacity of beads and their release data. Effects of variables such as PVA/NaAlg ratio, acrylamide content, exposure time to GA and drug/polymer ratio on the release of DS were discussed at three different pH values (1.2, 6.8, 7.4). It was observed that, DS release from the beads decreased with increasing PVA/NaAlg (m/m) ratio, drug/polymer ratio (d/p) and extent of cross-linking. However, DS release increased with increasing acrylamide content of the PVA-g-PAAm polymer. The highest DS release was obtained to be 92% for 1/1 PVA-g-PAAm/NaAlg ratio beads. It was also observed from release results that DS release from the beads through the external medium is much higher at high pH (6.8 and 7.4) than that at low pH (1.2). The drug release from the beads mostly followed Case II transport.