Mass spectral characterization of urinary metabolites of D,L-kawain

The urinary metabolism of D,L-kawain was studied in humans after an oral dose of 200 mg. Ten metabolites of kawain could be identified by gas chromatography-mass spectrometry with electron impact and chemical ionization. The main metabolic pathways were hydroxylation of the phenyl ring, reduction of the 7,8-double bond, hydroxylation of the lactone ring with subsequent dehydration and opening of the lactone ring. The metabolites were mainly excreted in the form of their conjugates.