A bioequivalence study of the Dong Wha Cisapril tablets(Dong Wha Pharm. Ind. Co., Ltd.) to the Prepulsid tablets(Janssen Korea Ltd.), formulations of cisapride, was conducted. Twenty four healthy Korean male subjects received each formulation at the dose of 5 mg as cisapride in a 2$ imes$2 crossover study. There was a 1-week washout period between the doses. Plasma concentrations of cisapride were monitored by an LC/MS method for over a period of 36 h after each administration. AUC(area under the plasma concentration- time curve from time zero to infinity) was calculated by the linear trapezoidal and extrapolation method. $C_{max}$ (maximum plasma drug concentration) and $T_{max}$ (time to reach $C_{max}$) were compiled from the plasma drug concentration-time data. Analysis of variance (ANOVA) revealed that there are no differences in AUC, $C_{max}$ and $T_{max}$ between the formulations. The apparent differences between the formulations in these parameters were all far less than 20% (i.e., 6.8, -6.6 and 1.8% for AUC, $C_{max}$ and $T_{max}$, respectively). Minimum detectable differences(%) at $alpha$=0.05 and 1-$eta$=0.8 were all less than 20% in these parameters between the formulations (i.e., 16.5, 11.4 and 16.4% for AUC, $C_{max}$ and $T_{max}$, respectively). The 90% confidence intervals for these parameters were also within 20% (i.e., -2.9~ 16.4, -13.2~0.1 and -7.8~ 11.4% for AUC, $C_{max}$ and $T_{max}$, respectively). These results satisfy the bioequivalence criteria of the Korea Food and Drug Administration (KFDA) guidelines (No. 98-51). Therefore, these results indicate that the two formulations of cisapride are bioequivalent and, thus, may be prescribed interchangeably.hangeably.y.hangeably.