Pharmacokinetics of [4-14C] mofebutazone after oral administration in man

The pharmacokinetics of mofebutazone was investigated in man after oral administration of [4-14C] mofebutazone in suspension form (7 mg/kg body weight). The blood concentration/time course was found to fit a two compartment open model with first order absorption (ka = 10.1 h-1) where elimination (kel = 0.304 h-1) occurs only from compartment 1. The maximum concentration was reached after 0.3 h in compartment 1 and after 2 h in compartment 2. Mofebutazone was found to be excreted almost exclusively via the kidney; 97% of the administered dose was found in urine already at 72 h. Excretion takes place very rapidly; 24% of the dose was excreted in 1.5 h and 45% in 3 h. 92% of the mofebutazone excreted was the conjugated form. Two glucuronides were detected in the 24 h urine; one of these seemed to be identical to a glucuronide fractionated from the urine of rat. The renal clearance of mofebutazone in man was found to be 3.38 l/h. The almost complete recovery of mofebutazone in the urine indicates that after oral administration, this drug has a very high bioavailability via the oral route.