Metabolism of flumecinol in humans.

1. The metabolism of 14C-flumecinol (3-trifluoromethyl-alpha-ethyl-benzhydrol) was studied in volunteers after a single oral dose of 100 mg (11.1 MBq; 300 microCi). Radioactivity excreted in urine was 78.8 +/- 6.0% of dose and in faeces was 12.0 +/- 5.3% dose in 120 h. 2. Unchanged flumecinol was not excreted in urine, but was present in faeces unconjugated (1.2% dose) and as conjugates of glucuronic and sulphuric acids (10.8% dose). 3. Enzymic hydrolysis showed that all urinary metabolites were conjugated with glucuronic and/or sulphuric acids (77.8% dose). Unconjugated urinary metabolites were not found. 4. The major route of flumecinol metabolism was hydroxylation of the alkyl side chain and/or the phenyl group followed by conjugation. 5. Both the CF3-group and the skeleton of the original compound remained intact during metabolism.