A bioequivalence study of the Loxipen tablets (Dae Wha Pharmaceutical Co., Korea) to the Loxonin tablets (Dong Hwa Pharmaceutical Co., Korea), formulations of sodium loxoprofen anhydrous 60㎎, was conducted. Sixteen healthy Korean male subjects received each formulation at the dose of 60㎎ as sodium loxoprofen anhydrous in a 2×2 crossover study. There was a 2-week washout period between the dose. Plasma concentrations of loxoprofen were monitored by an HPLC method for over a period of 6 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., 5.88, 7.81 and 6.09% for AUC, C_(max) and T_(max), respectively). Minimum detectable differences (%) at α=0.1 and 1-β=0.8 were all less than 20% difference in these parameters between the formulations were all over 0.8 (i.e., 15.81, 13.13 and 19.85 for AUC, C_(max) and T_(max), respectively). The 90% confidence intervals for these parameters were also within ±20% (i.e., -16.52∼4.77, -16.65∼1.02 and -19.45∼7.28% 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 2 formulations of loxoprofen are bioequivalent and, thus, may be prescribed interchangeably.