Objective: To examine the
pharmacokinetics of g atifloxacin in Chinese volunteers and work out the dosage regimens for the
treat ment of bacterial infections. Methods:Single and multiple dose pharmacokinetic study of gat ifloxacin were conducted in 9 and 8 healthy volunteers
respectively. The drug co ncentrations in serum and urine samples were assayed by high performance chromat ography. Results:①The
pharmacokinetics of gatifloxacin were fitted in a two compartment open m odel following oral administration of single dose of 200, 400 and 600 mg, the me an peak concentrations in serum being 2.39, 4.29 and 6.51 mg/L,respectively , the mean area under the concentration time curve ( AUC )being 15.44, 34.1 2 and 54.95 h·mg/L and the elimination half life (t 1/2β )being 7.38, 7. 82 and 7.56 h respectively. 82.51%, 82.03% and 79.15% of the doses were excreted in urine within 72 h after an oral dose of 200, 400 and 600 mg. A good linear c orrelation existed between administered doses and serum drug concentrations as w ell as AUCs . ②The pharmacokinetic parameters of gatifloxacin after the firs t and last dose were similar following the 400 mg multiple oral doses study. The peak concentration of the first and last dose were 3.98 mg/L and 4.76 mg/L; rea ched at 1.56 and 1.31 h after dosing, AUC being 33.59 h·mg/L and 35.87 h·m g/L, t 1/2β 7.60 h and 8.05 h respectively. The differences of c max and AUC between the first and last dose being statistically signific ant( P <0.05), there were no significant difference in other pharmacokinetic parameters. ③Only one subject in multiple dose(400 mg)study with transitory elevation of AST and ALT, no laboratory abnormal changes were found. Conclusions:Gatifloxacin is well tolerated, it is rapidly absorb ed with high peak concentration and long elimination half life. Based on the res ults of this study, we suggest gatifloxacin 400 mg once daily for systemic bacte rial infections and 200 mg once daily for lower urinary tract infections to be u sed in phase Ⅱ clinical trial of gatifloxacin.