Abstract
1. Disposition of phenol red was examined in channel catfish (Ictalurus punctatus) after oral or intravascular (i.v.) dosing at 10mg/kg body weight.
2. Phenol red was not detectable in plasma, urine, or bile after oral administration.
3. After i.v. dosing, plasma concentrations of phenol red were best described by a two-compartment pharmacokinetic model with distribution and elimination half-lives of 2–3 and 21min, respectively. The apparent volume of distribution at steady state (Vss) was 225 ml/kg and total body clearance (Clb) was 658 ml/h per kg. Plasma protein binding was 19%.
4. Biliary excretion was the primary route of elimination of phenol red; in 24 h, 55% of the i.v. dose was excreted in bile compared with 24% in urine. No metabolites were detected in these fluids.
5. The use of anaesthesia during dosing had no effect on the quantitative excretion of phenol red by renal or biliary routes.