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 mg, was conducted. Sixteen healthy Korean male subjects received each formulation at the dose of 60 mg as sodium loxoprofen anhydrous in a $2{ imes}2$ 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 ${alpha}=0.1$ and $1-{eta}=0.8$ 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 ${pm}20%$ (i.e., $-16.52{sim}4.77$, $-16.65{sim}1,02$ and $-19.45{sim}7.28%$ 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.