The metabolic fate of 4-amino-2-(4-butanoyl-hexahydro-1H-1, 4-diazepin-1-yl)-6,7-dimethoxy-quinazoline HCl.

1. 4-Amino-2-(4-butanoyl hexahydro-1H-1, 4-diazepin-1-yl)-6, 7-dimethoxy [2-14C]quinazoline HCl (14C-DDQ) is rapidly absorbed in rats and rabbits and excreted mainly into faeces via the bile. 2. The main metabolites in tissues and excreta are O- and N-glucuronides of 7-O-desmethyl DDQ in rats and the N-glucuronide of DDQ in rabbits. 3. Significant enterohepatic circulation of the metabolites occurs in rats. 4. The absorption of DDQ is also rapid in healthy humans and the plasma concentration decreases with an apparent half-life of 1 . 53h.