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

<b>Aim:</b> The goal of the present work was to formulate zein-decorated rifaximin (RFX) nanosuspension to attain sustained release as well as effectiveness against <i>Escherichia coli (E. coli)</i>. <b>Methods:</b> 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. <i>In vitro</i> antibacterial potential was elucidated using well diffusion method whereas MIC value was determined by microbroth dilution method against <i>E. coli</i> for RFX-NS and pure RFX. <b>Results:</b> 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). <i>In vitro</i> 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 <i>E. coli</i> displayed MIC value of 15.44 ± 0.01 μg/ml and 72.96 ± 0.25 μg/ml, respectively. <b>Conclusion:</b> The results highlighted a significance of nanosuspension for improving the solubility of RFX and its antibacterial potential against <i>E. coli</i>. 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.