Morphine metabolism in opiate dependent and normal men by double isotope techniques

A mixture of morphine-63H and morphine-N-14CH3 was administered to an opiate dependent and to a normal male subject. In both subjects the urinary excretion of radioactivity was rapid and exceeded 85% of the dose over 72 hours. The extent and time pattern of N-demethylation differed in the two subjects with N-demethylation of morphine being slower and less in the opiate addict. The use of the double isotope technique in detecting small changes in morphine metabolism is discussed.