Implementation of two different experimental designs for screening and optimization of process parameters for metformin-loaded carboxymethyl chitosan formulation

Metformin (MET) was effectively encapsulated into O-carboxymethyl chitosan (O-CMC) polymeric formulation using an experimental design method. Six factors Plackett–Burman (PB) design was utilized to find the significant process parameters. Linear equations used to study the effect of each process parameters on particle size (PS), encapsulation efficiency (EE), and zeta potential (ZP) and the most influential three factors decided for further optimization. Optimization was carried out by implementing three-factor three-level Box–Behnken (BB) design. Mathematical models were generated by regression analysis for responses of PS, EE, and ZP. Two-step experimental design took into account for the preparation of optimized formulation with maximum %EE (72.78 ± 9.7%) and minimum PS (225.67 ± 5.53 nm) at optimum process conditions with a ZP of –5.22 mV for the nano-polymeric formulation in an economical matter by reduction chemical use and formulation time. Furthermore, the biological activity of the final formulation was determined by in vitro cytotoxicity study compared to free MET. The cytotoxicity result reveals that both pure drug and nano-formulation biocompatible with MCF10A non-tumorigenic cell line and lethal for the MCF7 cell line. These in vitro results were the first helpful step to further investigate O-CMC loaded MET nanoparticles in diagnostic and therapeutic applications of breast cancer.