Similar profile of urinary and faecal metabolites of 14C-carmoisine in male and pregnant female rats after oral administration.

Pregnant rats received 14C-Carmoisine (200 mg kg-1; 25 microCi) by gavage on days 16-19 of gestation. The animals were killed and maternal tissues, amniotic fluid, placentae, foetal membranes and foetuses were analyzed for radioactivity. No evidence for the transplacental transfer of 14C-Carmoisine or its metabolites was obtained. Male rats were given a single oral administration of 14C-Carmoisine (200 mg kg-1; 25 microCi) and killed at different times after dosing. In both male and female animals, more than 90% of the radioactivity was excreted in faeces and urine within 64 h, and the results suggested that there was no significant absorption of the azodye and no preferential concentration of the red food colour or its metabolites in any particular tissue. Analyses by HPLC, combined with a radioactivity monitor (RAM), of urine and faeces of such animals show that five radioactive peaks were present in the radiochromatogram in addition to unmodified Carmoisine. The mean peak shows the retention time and the u.v. spectrum of authentic naphthionic acid. The results demonstrate that the pregnancy does not affect the kinetic and the metabolic profile of a single oral administration of the azodye Carmoisine given at different days of gestation.