Development of fexofenadine self-microemulsifying delivery systems: an efficient way to improve intestinal permeability

<b>Aim:</b> The present study aimed to prepare and evaluate fexofenadine self-microemulsifying drug-delivery systems (SMEDDS) formulation and to determine and compare its intestinal permeability using <i>in situ</i> single-pass intestinal perfusion (SPIP) technique. <b>Methods:</b> Fexofenadine-loaded SMEDDS were prepared and optimized. Droplet size, polydispersity index, zeta potential, drug release and intestinal permeability were evaluated. <b>Results:</b> Optimized formulation consisted of 15% oil, 80% surfactant and 5% cosolvent. Droplet size and drug loading of optimized formulation was 13.77 nm and 60 mg/g and it has released 90% of its drug content. Intestinal permeability of fexofenadine was threefold enhanced in SMEDDS compared with free fexofenadine. <b>Conclusion:</b> The results of our study revealed that SMEDDS could be a promising tool for oral delivery of fexofenadine with enhanced dissolution rate and intestinal permeability. A mixture of turpentine oil/castor oil (3:1) and ethyl oleate was selected as the oil phase and Tween 80 and PEG 600 are selected as the surfactant and cosolvent to prepare the fexofenadine-loaded self-microemulsifying drug-delivery systems (SMEDDS). 36 different SMEDDS formulations with varying ratios of oil, surfactant and cosolvent were prepared and their state of homogeneity and stability were evaluated. F8 formulation produced droplets with smaller sizes compared with F6, F7 and F15. All of the SMEDDS formulations have released more than 50% of their drug content in 30 min. There were no signs of creaming, phase separation, layering and droplet size change in F6, F and F8 formulations after facing to freeze–thaw and centrifugation tests. The ratios of corrected outlet to inlet fexofenadine concentrations obtained from SPIP studies were used to determine reaching the steady state and calculating intestinal effective permeabilities. An approximately threefold improvement was seen in the intestinal effective permeability of fexofenadine from SMEDDS compared with free fexofenadine suspension. Human intestinal permeabilities of SMEDDS formulaton and free fexofenadine suspension was predicted.