Pharmacokinetics, tissue distribution, and excretion of buagafuran in rats

The pharmacokinetics, tissue distribution, and excretion of buagafuran (BF, 4-butyl-α-agarofuran), a promising antianxiety drug isolated from Gharu-wood (Aquilaria agallocha Roxb), were investigated in rats. BF plasma concentration was determined in rats after oral and intravenous doses by GC-TOF-MS. BF showed nonlinear pharmacokinetics after oral and intravenous administration of 4, 16, and 64 mg/kg. The AUC(0-∞) and C(max) did not increase proportionally with doses, indicating the saturation in absorption kinetics of BF in rats after oral dosage. BF absorption was extremely poor with an absolute bioavailability below 9.5%. After oral administration of (3)H-BF (4 mg/kg) to rats, radioactivity was well distributed to the tissues examined. The highest radioactivity was found in gastrointestinal tract, followed by liver and kidney. Radioactivity in brain, as a target organ, was about 20-40% of that in plasma at all time points. Total mean percent recovery of radioactive dose was about 80% in rats (51.2% in urine; 28.7% in feces). Bile elimination was also the major excretion route of BF, and 45.4% of the radioactive dose was recovered in bile.