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This study investigates the shape of a cruciform specimen that is stretched in the normal direction of the minimum cross section using FEM. In addition, plane strain tensile states exist in the measurement region in order to determine the forming limit diagram not by an arbitrary stress ratio but by the strain ratio. We propose two types of cruciform specimens. One is a flat-type cruciform specimen, which has deep slits in the middle of the arm region in the width direction. The other specimen is a reduced measurement region type, which also has deep slits as well as a shape that is a biaxial combination of two plane strain tensile specimens. We analyze equibiaxial tensile tests of these two proposed cruciform specimen types using FEM.

This study aimed to develop a cyclosporine A (CsA)-loaded ternary solid dispersion (tSD/CsA) to improve the storage stability of a solid dispersion (SD) system and the oral absorbability of CsA. Hydroxypropyl cellulose (HPC) and hydroxypropyl methylcellulose acetate succinate (HPMCAS) were selected as carrier materials of tSD, and tSD/CsA was prepared with a fine droplet drying process, a powderization technology that employs an inkjet head. The physicochemical properties of tSD/CsA were evaluated in terms of morphology, storage stability, dissolution behavior, and mucoadhesive property. After the oral administration of CsA samples (10 mg-CsA/kg) to rats, the plasma concentration of CsA was monitored to estimate oral absorbability. tSD/CsA comprised uniform shriveled particles with a diameter of 3.4 mm and span factor of 0.4, which is a parameter to estimate the particle size distribution. Although HPC-based binary SD showed marked aggregation of the particles after storage under 40 °C/75% relative humidity, there were no significant aggregations of tSD/CsA, due to the relatively low hygroscopic property of HPMCAS. The pH-dependent release of CsA with improved dissolution was observed in tSD/CsA. In the in vitro mucoadhesive evaluation using a mucin disk, tSD/CsA exhibited a better mucoadhesive property than HPC-based SD, possibly leading to prolonged retention of tSD particles in the gastrointestinal tract after oral administration. Orally-dosed tSD/CsA in rats resulted in significantly improved oral absorption of CsA, as evidenced by a 27-fold higher bioavailability than amorphous CsA. tSD/CsA may be a promising dosage option to improve the storage stability of a SD system and the biopharmaceutical properties of CsA.

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