3-O-methyldobutamine, a major metabolite of dobutamine in humans.

Dobutamine is a synthetic ionotropic catecholamine commonly used to treat heart failure and shock. The catabolic fate of dobutamine in humans has yet to be reported, although formation of 3-O-methyldobutamine represents the principal pathway of dobutamine disposition in the dog. Herein, we describe the isolation and identification of 3-O-methyldobutamine in the urine of children receiving infusions of racemic dobutamine. In a 9-year-old child with heart failure approximately 80% of dobutamine administered intravenously at steady state was detected in the urine. Forty-seven percent of infused dobutamine was identified as 3-O-methyldobutamine and its acid-hydrolyzed derivatives, the latter mostly conjugated with sulfate (33%). Thirty-two percent consisted of acid-hydrolyzed dobutamine metabolites, primarily conjugated with sulfate (16%). Sonicates of human blood mononuclear cells catalyzed the formation of 3-O-methyldobutamine from dobutamine and S-adenosylmethionine in vitro. These findings indicate that formation of 3-O-methyldobutamine constitutes a major pathway of dobutamine metabolism in humans.