Synthesis of nicotinamide-based molecularly imprinted microspheres and in vitro controlled release studies

Nicotinamide (NAM), which is one of the two principal forms, together with nicotinic acid, of vitamin B3, is both a food nutrient and a drug. Controlled NAM release systems are useful to extend the duration of the drug's pharmacological activity and to minimize administration frequency. In this paper, molecularly imprinted polymers (MIPs) have been used as unconventional synthetic polymeric carriers, to prepare drug delivery systems for sustained release of NAM molecules. In the present study, various MIPs micro-spheres have been synthesized by using methacrylic acid as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross-linker. Different stoichiometric ratios of the reagents have been used, in order to evaluate their influence on NAM recognition and release properties. Non-imprinted systems have been also been prepared as controls. MIPs binding capacity has been evaluated; NAM loading and in vitro release studies, in buffer solution (pH 7.2), that mimics blood plasma conditions, have been performed. Polymer P4 has given the best results since it enables it to rebind selectively and to prolong the release of NAM with higher performance than the non-imprinted one.