Enrofloxacin pharmacokinetics in Takifugu flavidus after oral administration at three salinity levels

The present study was designed to explore the pharmacokinetics of enrofloxacin in Takifugu flavidus at different salinity levels (10 parts per thousand, 20 parts per thousand and 30 parts per thousand). The concentrations of enrofloxacin in plasma and tissues (kidney, liver and muscle) of T. flavidus after a single oral dose of 10mgkg(-1) were simultaneously determined using HPLC. The parameters of pharmacokinetics were calculated using non-compartmental model based on statistic moment theory. The peak concentrations of enrofloxacin were higher and T-max values in plasma, liver and muscle tissues of T. flavidus were lower at the salinity of 20 parts per thousand and 30 parts per thousand than that of 10 parts per thousand, except the kidney tissue. These demonstrated the absorption of enrofloxacin was more quickly and more quantity at the high salinity. The elimination half-life (t(1/2z)) of enrofloxacin in the plasma (45.22, 69.91 and 95.45h) was increasing with the increase in salinity. And the t(1/2z) values of enrofloxacin in liver (76.44, 44.21 and 33.48h) and kidney (212.16, 157.43 and 35.61h) both decline with the increase in salinity, indicating the elimination of enrofloxacin was faster in liver and kidney but slower in plasma at the high salinity. The content of enrofloxacin in liver was increasing with the increase in salinity, suggesting that salinity affects tissue distribution and metabolism in T. flavidus. In addition, the AUC(0-) data of enrofloxacin (kidney>plasma>liver>muscle) at different salinity levels were essentially consistent, and AUC(0-) data of kidney were declined with the increase in salinity, supporting that the kidney was the main organ and the role of extent of kidney on excretion was different in different salinity levels.