Pectin grafted poly(N-vinylpyrrolidone): optimization and in vitro controllable theophylline drug release

The present article describes preparation, optimization, and characterization of pectin grafted polyvinylpyrrolidone hydrogels followed by controllable theophylline drug release. The gels were prepared in the presence of N,N′–methylenebisacrylamide (MBAA) crosslinker and ceric ammonium nitrate (CAN) initiator under N2 atmosphere. Optimum conditions, in terms of percent of grafting (%G), were determined as follows: Pectin = 1.0 g, [NVP] = 2.81 mM, [MBAA] = 0.65 mM, [CAN] = 0.073 mM, polymerization temperature = 30°C and time = 4.0 hrs. Hydrogels were characterized by FTIR, TGA, DSC, XRD, and SEM. In vitro controllable release of theophylline model drug was studied using different N-vinylpyrrolidone monomer to MBAA crosslinker ratio (i.e., [NVP]/[MBAA] ratios) and different polymerization temperatures at two pH values, namely 5.5 and 7.4. The optimum conditions for colon-targeted vehicles that could provide the least theophylline release at pH 5.5, and the most theophylline release at pH 7.4, were as follows: [NVP]/[MBAA] = 4.33, polymerization temperature = 10°C and %G = 62.2. Such promising hydrogel characteristics may play the key role in many future drug release implementations.