The Metabolic Fate of Endrin in the Rabbit

Abstract

1. [¹⁴C]Endrin, administered orally to rabbits, is excreted in the faeces as unchanged endrin (50% of that administered) and in the urine as a mixture of polar metabolites.

2. The major biotransformation is hydroxylation at the methylene bridge (C-12) to yield anti-12-hydroxyendrin. syn-Hydroxylation at C-12 also occurs.

3. The hydroxylated metabolites are excreted mainly as their sulphate conjugates.

4. Glucuronide conjugates are also excreted. anti-12-Hydroxyendrin is rapidly conjugated in vitro on incubation with rabbit liver microsomal glucurcnyl transferase and UDPGA.

5. Comparative aspects of the metabolism of endrin in rats and rabbits are discussed.