To estimate the dissolution of the designed S-309309-based formulations in the small intestine, formulations (Table ) were prepared using HPC, which increased the wettability of S-309309, and encapsulated to suppress the increase of compound 8 amount under acidic conditions. The dissolution profile of each formulation in phosphate buffer (pH 6.8) was assessed, as shown in Fig. ). In addition, the effect of HPC on the dissolution of S-309309 was evaluated. Although a lag time of up to 5 min after the start of the test was observed regardless of the presence or absence of HPC, all the capsules containing HPC showed rapid dissolution behavior compared with the capsules without HPC regardless of S-309309 dose. These results demonstrated that the wettability improvement induced by HPC accelerated the dissolution rate of S-309309. Thus, the formulations containing HPC can be expected to show better dissolution and subsequent absorption in the small intestine than the formulations without HPC.