Demethylation of C14-Labelled Codeine in the Rat.

Abstract

Radio-codeine is demethylated in vitro and in vivo, the labelled methoxy group being oxidized to C14O2 which is expired by the lungs. The site of the demethylation process is primarily the liver; 40% of the injected dose is demethylated within 6 hours. Transmethylation has not been demonstrated in vitro.