Disposition and metabolism of isoeugenol in the male Fischer 344 rat

The primary objective of these studies was to determine the absorption, distribution, metabolism and excretion of isoeugenol following oral and intravenous administration to male Fischer-344 rats. Following a single oral dose of [¹⁴C]isoeugenol (156 mg/kg, 50 μCi/kg), greater than 85% of the administered dose was excreted in the urine predominantly as sulfate or glucuronide metabolites by 72 h. Approximately 10% was recovered in the feces, and less than 0.1% was recovered as CO₂ or expired organics. No parent isoeugenol was detected in the blood at any of the time points analyzed. Following iv administration (15.6 mg/kg, 100 μCi/kg), isoeugenol disappeared rapidly from the blood. The t_1/2 was 12 min and the Cl_s was 1.9 l/min/kg. Excretion characteristics were similar to those of oral administration. The total amount of radioactivity remaining in selected tissues by 72 h was less than 0.25% of the dose following either oral or intravenous administration. Results of these studies show that isoeugenol is rapidly metabolized and is excreted predominantly in the urine as phase II conjugates of the parent compound.