Background　Visiclear^® Combination Tablets, containing solid-form sodium phosphate, were launched as a preparatory medication for colonoscopy；however, some insoluble ingredients have been occasionally observed in the colonic lumen after the administration. Hence, Z-209 was innovatively developed as a bowel cleansing agent where a reduced amount of insoluble ingredients was observed. The aim of this study was to demonstrate bioequivalence of Z-209 to Visiclear^® .
Methods　Twenty-five healthy male Japanese volunteers who met both inclusion and exclusion criteria were enrolled in a non-blind cross-over study；eighteen of these candidates aged 20 to 42 years old were administered Z-209（50g）and Visiclear^®（50g）in a randomised order with a 14-day washout period. The levels of serum phosphorus were determined at ten identical points within 24 hours after administration. The study was approved by an institutional review board and written informed consent was obtained from all participants.
Results　No discrepancies were found in the level of AUC_0-24hr, C_max, T_max and t_1/2 in both Z-209 and Visiclear^®. In addition, the 90％ confidence intervals of AUC_0-24hr and C_max were log（0.978）to log（1.023）and log（0.960）to log（1.038）, respectively, both of which were within the range stipulated in the guidelines for bioequivalence studies. Furthermore, no serious adverse events were observed. There was no marked difference in number observed at each group, and all the events were reported in the clinical laboratory tests.
Conclusion　Z-209 was biologically equivalent to Visiclear^® Combination Tablets.