Loxoprofen sodium, a 2-phenylpropionate non-steroidal anti-inflammatory drug (NSAID), has marked analgesic and antipyretic activities and relatively weak gastrointestinal ulcerogenicity. The purpose of the present study was to evaluate the bioequivalence of two loxoprofen sodium tablets, Hana loxoprofen sodium tablet (Hana Pharm. Co., Ltd.) and Dongwha Loxonin$^{(R)}$ tablet (Dongwha Pharm. Co., Ltd.), according to the guidelines of the Korea Food and Drug Administration (KFDA). The in vitro release of loxoprofen from the two loxoprofen sodium formulations was tested using KP IX Apparatus II method with various dissolution media. Twenty four healthy Korean male volunteers, $22.83{pm}1.862$ years in age and $69.92{pm}9.14$ kg in body weight, were divided into two groups and a randomized $2{ imes}2$ crossover study was employed. After a single tablet containing 60 mg as loxoprofen sodium was orally administered, blood samples were taken at predetermined time intervals and the concentrations of loxoprofen in serum were determined using a online column-switching HPLC method with UV/Vis detection. The dissolution profiles of two formulations were similar in all tested dissolution media. The pharmacokinetic parameters such as $AUC^t$, $C_{max}$ and $T_{max}$ were calculated, and computer programs (Equiv Test and K-BE Test 2002) were utilized for the statistical analysis of the parameters using logarithmically transformed $AUC_t$, $C_{max}$ and un-transformed $T_{max}$. The results showed that the differences between two formulations based on the reference drug, Dongwha Loxonin$^{(R)}$ tablet, were 2.03, 2.99 and -9.49% for $AUC_t$, $C_{max}$, and $T_{max}$, respectively. There were no sequence effects between two formulations in these parameters. The 90% confidence intervals using logarithmically transformed data were within the acceptance range of log0.8 to log1.25 (e.g., log0.9831~log1.0535 and log0.9455~log1.1386 for $AUC_t$ and $C_{max}$, respectively). Thus, the criteria of the KFDA bioequivalence guideline were satisfied, indicating Hana loxoprofen sodium tablet was bioequivalent to Dongwha Loxonin$^{(R)}$ tablet.
