Absorption, distribution and metabolism of propyl anthranilate

Analysis of the gut contents of rats killed at intervals after dosage with propyl anthranilate or anthranilic acid suggested that both acid and ester were absorbed rapidly; the chief site of absorption was the stomach. Not more than a trace of the ester was hydrolysed in the stomach but of the dosed ester detected in the small intestine (less than 7%) a considerable proportion, increasing with time after dosing was present as anthranilic acid. Measurement of the level of radioactivity in the blood after administration of 14C-labelled propan-1-ol, propyl anthranilate or anthranilic acid showed that the alcohol was absorbed more rapidly than either the ester or acid. Unchanged propyl anthranilate was readily detected in the blood of rats dosed with the ester and some unhydrolysed ester was excreted in the urine. The level of radioactivity of the organs of rats 2 h and 4 h after administration of the 14C-labelled compounds was measured. Velocity constants for the excretion of 14CO2 by rats dosed with 14C-labelled propyl anthranilate were significantly lower than those found for rats dosed with [14C]propan-1-ol indicating a limiting step in the metabolism of the propyl moiety of the ester which did not occur in the metabolism of propan-1-ol. The urinary metabolites of anthranilic acid excreted by rabbits and rats dosed with the acid were qualitatively the same as those excreted by these species after dosing with propyl anthanilate; some quantitative differences were however, observed.