The metabolic disposition of 14C-labelled green S and brilliant blue FCF in the rat, mouse and guinea-pig

The absorption, metabolism and excretion of 14C-labelled Green S and Brilliant Blue FCF have been studied in the rat, mouse and guinea-pig. Following administration of a single oral dose of Green S at either 100 μg/kg or 10 mg/kg of Brilliant Blue FCF at either 30 μg/kg or 3 mg/kg to male or female rats, substantially all of the dose was excreted unchanged in the faeces within 72 hr. Pretreating male rats with unlabelled Green S or Brilliant Blue FCF in the diet (100 or 30 mg/kg day, respectively) for 21 days prior to dosing with 14C-labelled colouring had no effect on the route of excretion or the time taken to eliminate all of the label. Similarly male mice and guinea-pigs excreted in the faeces all of a single oral dose of Green S or Brilliant Blue FCF. The lack of absorption and metabolism of the labelled dye in the gastro-intestinal tract of all three species investigated was confirmed by studies using isolated loops of small intestine. It was shown that no radioactivity was taken up by the foetuses of pregnant rats given 14C-labelled Green S or Brilliant Blue FCF.