Enhanced oral bioavailability of cyclosporine A by liposomes containing a bile salt

The main purpose of this study was to evaluate liposomes containing a bile salt, sodium deoxycholate (SDC), as oral drug delivery systems to enhance the oral bioavailability of the poorly water-soluble and poorly permeable drug, cyclosporine A (CyA). Liposomes composed of soybean phosphatidylcholine (SPC) and SDC were prepared by a thin-film dispersion method followed by homogenization. Several properties of the liposomes including particle size, polydispersity index, and entrapment efficiency were characterized. The in vitro release of CyA from these liposomes was less than 5% at 12 hours as measured by a dynamic dialysis method. The pharmacokinetic results in rats showed improved absorption of CyA in SPC/SDC liposomes, compared with CyA-loaded conventional SPC/cholesterol (Chol) liposomes and microemulsion-based Sandimmune Neoral®. The relative oral bioavailability of CyA-loaded SPC/SDC and SPC/Chol liposomes was 120.3% and 98.6%, respectively, with Sandimmun Neoral as the reference. The enhanced bioavailability of CyA was probably due to facilitated absorption by the liposomes containing SDC rather than improved release rate

Vortex Evolution Behavior in Self-Assembly of Flow Units in Metallic Glasses

Shear banding in amorphous metals originates from the activation and percolation of flow units. To uncover the self-assembly dynamics of flow units in metallic glasses, a rectangular sample with two flow units embedded in the matrix undergoing simple shearing was analyzed using finite element simulations. The vortex evolution behavior, including activation, growth, and collapse during the self-assembly of flow units, was revealed. It was found that the formation of a mature vortex indicates the onset of yielding, and the collapse of the vortex represents the percolation of flow units or shear localization. The effects of initial free volume distribution and the distance between flow units on vortex behavior were also studied. Increasing the initial free volume concentration within flow units or the matrix leads to a gentler vortex evolution process and better homogeneous plasticity. The shape of vortex tends to be "flatter" with the increase in flow units' spacing, and the optimal spacing was found to maximize the strength of the material