Kinetics on Uptake of Drugs in Goldfish. II. Uptake of Benzoic Acid, Phenol, Phenobarbital and Pentobarbital

Abstract

Absorption of benzoic acid, phenol, phenobarbital, and pentobarbital from water by goldfish was studied kinetically. The absorption membrane of goldfish was thought to be like a lipid membrane for the absorption of these chemicals at various pH. Addition of urea (1M) to the water promoted absorption rate of each chemical, as was the case with salicylic acid.³⁾ There was a difference in the order of absorption rate of these chemicals between goldfish and their intestinal absorption in rats.⁴⁾ The ratio of equilibrium concentration of the chemicals between goldfish and water did not agree with the pH-partition equilibrium theory, either in the variance of pH or of chemicals. The amount of absorption estimated from the decrease of chemicals in water was completely recovered in the homogenate of goldfish. Concentration of the chemicals in goldfish organs was the highest in the gills for all the chemicals tested. The observed excretion rate of benzoic acid from goldfish in fresh water, after the absorption experiment, was consistent with the kinetic theory during the first 2 min but decreased rapidly thereafter.