Pharmacokinetics of sodium nifurstyrenate in cultured yellowtail after oral administration

The pharmacokinetics and tissue levels of sodium nifurstyrenate (NFS) were studied in cultured yellowtail after oral administration at a dose of 100 mg/kg. NFS levels were determined by our high performance liquid chromatographic (HPLC) method. The recoveries from spiked serum and tissues were 97, 90, 97, 90 and 98% for serum, muscle, liver, kidney and bile, respectively. The detection limit of the method was 0.05 μg/ml for serum, muscle, liver and kidney, and 0.1 μg/ml for bile. Serum levels of NFS could be evaluated by a one-compartment model with first-order absorption. The theoretical time to peak serum concentration of drug ( t max) was 1.9 h, and the concentration at t max was 6.98 μg/ml. The area under the serum concentration-time curve (AUC) and the mean residence time calculated from AUC were 31.6 μg/ml and 3.0 h. The elimination half-life ( T 1 2β ) was 1.4, 2.4, 29.7 and 1.5 h for serum, muscle, liver and kidney, respectively. The elimination time ( E t ) was calculated as 16.2, 9.5, 101 and 15.0 h for serum, muscle, liver and kidney, respectively, from their elimination curves. The T 1 2β and E t of NFS in bile could not be calculated because the elimination phase could not be recognized until 96 h.