SUMMARY After an oral dose of 350 mg of sulphadimethoxine, the turtle Pseudemys scripta elegans 0-dealkylates sulphadimethoxine at the 2-and 6-position at 38% and 19% respectively, the 2-position being favoured. Acetylation of sulphadimethoxine and its hydroxy metabolites occurs for 57.4%.

Sulphamonomethoxine is O-demethylated at the 6 position and oxidised at the 2 position of the pyrimidine substituent by Pseudemys scripta elegans. No N4-acetylation takes place. The yield of the oxidation reaction is twice that of the O-demethylation reaction.