S-309309 capsule formulations were composed of the common pharmaceutical excipients (mannitol, HPC, low-substituted hydroxypropyl cellulose, magnesium stearate, and HPMC capsule) without any special excipients and were manufactured by simple manufacturing processes such as mixing, and encapsulation. The formulae used are listed in Table . Dissolution tests were conducted with a dissolution apparatus (NTR-6400AC; Toyama Sangyo Co., Ltd. Osaka) following the paddle method (the United States Pharmacopeia (USP) Apparatus II) at 50 rpm and 37°C. S-309309 capsule formulations were tested in 900 mL of 200 mM phosphate buffer (pH6.8). A sinker was used for the dissolution test. Five-mL aliquots of the test solution were collected at 5, 10, 15, 20, 30, 45 and 60 min. Each aliquot was filtered through a 0.45-µm filter. The filtrate was injected into UPLC system. UPLC analysis was performed at a wavelength of 267 nm with a YMC-Triart C18 ExRS column (1.9 µm, 3.0 × 100 mm) under an isocratic condition of mobile phase (0.1% formic acid:acetonitrile, 3:2, v/v) for 5 min at 60°C using a column heater. The detection wavelength was set at 267 nm and the injection volume was 5 µL.