Decreased oral bioavailability of loxoprofen at second administration in human subjects

The objective of this study was to determine the extent of period effect on the pharmacokineitcs of loxoprofen during consecutive dosing. Loxipen and Loxonin tablets were administered to 16 healthy Korean male subjects at a s ingle dose of 60 mg as loxoprofen sodium anhydrous in a 2 x 2 crossover inv estigation with a two-week wash-out phase. Concentrations of loxoprofen in plasma were measured by HPLC method for 6 h. The two formulations were foun d bioequivalent, but analysis of variance (ANOVA) indicated that there was a significant (p < 0.05) period effect in AUC(inf) (area under the plasma c oncentration-time curve from time zero to infinity) between the administrat ions. A 20% decrease in the AUC was seen at the second administration. This period effect on pharmacokinetics of loxoprofen may be relevant for the pa tients who need consecutive administration of the drug.