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The aim of this study was to prepare and evaluate ion-activated in situ gel ophthalmic drug delivery system based on κ-carrageenan (KC), using acyclovir as a model drug, hydroxypropyl methylcellulose (HPMC) as the viscosity agent and hydroxypropyl-β-cyclodextrin (HP-β-CD) as the penetration enhancer. The two ternary phase diagrams exhibited the effect of K and Ca on the sol-to-gel transition, which turned out that KC was more sensitive to K. The optimal ophthalmic matrix (prepared from KC and HPMC) was optimized with in vitro drug release test. The apparent permeability coefficient of acyclovir under 2% HP-β-CD was found to have dramatically increased (2.16-ploid) than that of conventional eye drops (p < .05). The ion-activated in situ gel based on KC significantly delayed drug release and its bioavailability could be improved in comparison with the conventional eye drops. Hence, it has the potential to be a novel kind of ocular drug delivery system.

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The aim of this article was to design a self-emulsifying drug delivery system (SEDDS) of loaded cepharanthine (CEP) to improve the oral bioavailability in rats. Based on the solubility determination and pseudo-ternary phase diagram, isopropyl palmitate (IPP) was chosen as the oil phase. Meanwhile, Cremophor RH40 and Macrogol 200 (PEG 200) were chosen as the emulsifier and co-emulsifier, respectively. This prescription was further optimized by using central composite design of response surface methodology. The optimized condition was CEP:IPP:Cremophor RH40:PEG 200=3.6:30.0:55.3:11.1 in mass ratio with maximum drug loading (36.21 mg/mL) and the minimum particle size (36.70 nm). The constructed CEP-SEDDS was characterized by dynamic light scattering, transmission electron microscopy, in vitro release and stability studies. The dissolution level of CEP-SEDDS was nearly 100% after 30 min in phosphate-buffered saline (PBS, pH 6.8) which was higher than that of the pure CEP (approximately 20%). In addition, in vivo pharmacokinetic study in rats showed that CEP-SEDDS dramatically improved bioavailability compared with active pharmaceutical ingredient (API) (the relative bioavailability was 203.46%). In this study, CEP-SEDDS was successfully prepared to enhance the oral bioavailability which might facilitate to increase its better clinical application. Graphical abstract