Zein decorated rifaximin nanosuspension: approach for sustained release and anti-bacterial efficacy enhancement

Aim: The goal of the present work was to formulate zein-decorated rifaximin (RFX) nanosuspension to attain sustained release as well as effectiveness against Escherichia coli (E. coli). Methods: The RFX nanosuspension was fabricated by using antisolvent addition method followed by coating using hydroalcoholic zein solution. The optimized RFX-NS and RFX-NS@zein was lyophilized for further spectroscopic evaluations. In vitro antibacterial potential was elucidated using well diffusion method whereas MIC value was determined by microbroth dilution method against E. coli for RFX-NS and pure RFX. Results: Box-Behnken Design was employed to assess the effects of independent variables on quality target product profile of RFX-NS. Optimized RFX-NS depicted particle size of 193.5 ± 4.45 nm with 76.49 ± 1.71% drug content. The significant change in particle size and zeta potential confirmed the formation of zein coated RFX-NS (RFX-NS@zein). In vitro release study depicted, 96.91 ± 1.21% release of RFX from RFX-NS in 6 h whereas 97.47 ± 1.99% RFX release was observed from RFX-NS@zein at the end of 12 h. Antibacterial assay of RFX-NS and free RFX against E. coli displayed MIC value of 15.44 ± 0.01 μg/ml and 72.96 ± 0.25 μg/ml, respectively. Conclusion: The results highlighted a significance of nanosuspension for improving the solubility of RFX and its antibacterial potential against E. coli. Rifaximin nanosuspension (RFX-NS) was prepared by antisolvent addition method owing to low solubility of RFX in aqueous phase. RFX-NS was coated with zein (RFX-NS@zein) to allow RFX-NS release in intestine. Box-Behnken design (33) was utilized to evaluate the impact of formulation variables on particle size (nm), zeta potential (mV) and drug content (%). Compared with pure RFX, RFX-NS displayed significantly high aqueous solubility due to submicron particle size. Inhibitory concentration (IC50) for RFX-NS was found to be significantly lower in comparison to pure RFX.