Gingerich, W. H., Meinertz, J. R., Dawson, V. K., Gofus, J. E., Delaney, L. J.,
and Bunnell, P. R., 1995, Distribution and elimination of [super(14)C]
sarafloxacin hydrochloride from tissues of juvenile channel catfish (Ictalurus
punctatus): Aquaculture, v. 131, no. 1-2, p. 23-36.

Abstract

The distribution and loss of radioactivity from tissues were determined in 60
juvenile channel catfish (Ictalurus punctatus) following oral dosing with the
candidate fish therapeutant Sarafin registered ([ super(14)C] sarafloxacin
hydrochloride) at 10 mg/kg for 5 consecutive days. Twelve groups of 5 fish each
were sampled at selected times ranging from 3 to 240 h after the last dose was
administered. The concentration and content of sarafloxacin-equivalent activity
was determined in liver, gallbladder, kidney, skin, and skinless fillet by sample
oxidation and liquid scintillation counting; content of sarafloxacin-equivalent
activity was determined in stomach and anterior and posterior intestines. Skinless
fillet tissues were also analyzed for sarafloxacin and for potential metabolites by
gradient-elution high-performance liquid chromatography (HPLC) with in-line
radiometric and fluorescence detection. Loss of radioactivity from the whole
body conformed to a bimodal elimination pattern with a rapid initial phase (t sub(
one half ) = 11 h) and a slower secondary phase (t sub( one half ) = 222 h).
Tissue and contents of the gastrointestinal tract (i.e. stomach and anterior and
posterior intestines) were a principal depot of activity during the first four sample
times (3, 6, 12, and 24 h); the combined head, skeleton, and fins (i.e. residual
carcass) were the principal depot of activity in samples taken after 24 h. Of those
tissues sampled 3 h after the last dose relative sarafloxacin concentration was
greatest in the liver (4.06 mu g equivalents/g) and least of the residual carcass
(1.13 mu g equivalents/g). Intermediate concentrations were found in the kidney
2.04 mu g equivalents/g), skinless fillet (1.71 mu g equivalents/g), and the skin
(1.51 mu g equivalents/g). Concentrations of sarafloxacin-equivalent residues in
edible skinless fillet were consistently among the lowest of all tissues examined.
The highest mean concentration of parent-equivalent material in the fillet tissue
was found 12 h after administration of the last dose (2.27 mu g equivalents/g)
and declined thereafter. Sarafloxacin constituted between 80 and 90% of the
extractable radioactive residues from the fillet homogenates. No other peaks were
resolved in any of the fillet tissue samples analyzed by HPLC with in-line
radiometric detection.

Keywords

Ictalurus-punctatus, juveniles, fish-physiology, radioactive-tracers, metabolites,
tissues, disease-control, fish-culture