Abstract: AIM: To study the chronopharmacokinetics of levofloxacin in rats. METHODS: After levofloxacin was orally given to rats at different times, the concentrations of levofloxacin in plasma and urine were determined by HPLC and the pharmacokinetics parameters were calculated. RESULTS: The mean pharmacokinetic parameters of levofloxacin at 8:00, 16:00 and 24:00 were C_max 2.37, 2.02 and 2.85 mg/L;t_max 0.56, 0.50 and 0.62 h;AUC_0-∞ 11.23, 9.89 and 11.77 mg·h·L^-1;t_1/2 4.23, 3.51 and 4.46 h;CLs 0.39, 0.57 and 0.36 L·kg^-1·h^-1, respectively.The main pharmacokinetic parameters showed no significant difference by oral administration at 8:00, 16:00 and 24:00. CONCLUSION: There was no obvious change in circadian rhythms of levofloxacin in rats.

Key words: levofloxacin, HPLC, chronopharmacokinetics, circadian rhythms