Distribution study of a synthetic ACTH analogue in rat tissue.

Tissue distribution of (Aib1, Lys17, 18, 19)-corticotrophin-(1-19)-nonadecapeptide amide (690024-S), iv injected to hypophysectomized rats, were surveyed by bioassay. Among the tissues examined. the largest amount of 690024-S was found in the liver during 3 h of search for the injection, while a higher concentration of the peptide per tissue weight was found in kidney. Though a small amount of 690024-S was detected in spleen, heart and lung at an early stage, it was not detectable in other tissues such as brain, stomach, small intestine, thigh muscle, fat or foetus. The peptide was found to be excreted into bile for the duration of about 2 h. It was also found that the elimination of 690024-S in blood followed biphasic first order kinetics.