Disposition of [4-14C]mofebutazone in the rat

The absorption and elimination of radioactivity after the oral or intraperitoneal administration of[4-14C]mofebutazone was studied in rats. The blood concentration of radioactivity reached a maximum after about 0.7 h, fell rapidly until about 2 h, and then declined slowly. There was sometimes a second peak between 3-6 h. Elimination of radioactivity in urine and feces was extensive and rapid. Over a 24 h period, 73% of the orally administered radioactivity was eliminated in the urine and 15% in the faeces; most of this was eliminated during the first 8 h (89% of the urine radioactivity, 56% of the faeces radioactivity). In anaesthetized rats with cannulated bile ducts, 94% of the intraperitoneally injected radioactivity was eliminated in the bile over a 6 h period. Most of the radioactivity (about 85%) eliminated in the bile and the urine was in the form of a glucuronide and only small amounts less than 10%, was in the form of mofebutazone.