Comparison of the Tissue Distribution and Metabolism of AN1284, a Potent Anti-Inflammatory Agent, After Subcutaneous and Oral Administration in Mice

Purpose. To establish a liquid chromatography/mass spectrometry method to compare the tissue distribution and metabolism of AN1284 after subcutaneous and oral administration at doses causing maximal reductions in IL-6 in plasma and tissues of mice. Methods. Lipopolysaccharide activated RAW 264.7 macrophages were used to detect the anti-inflammatory activity of AN1284 and its metabolites. Mice were given AN1284 by injection or gavage, 15 min before lipopolysaccharide. The reduction of IL-6 measured after 4h. Results. AN1284 is metabolized to the indole (AN1422), a 7-OH derivative and its glucuronide. AN1422 had weaker anti-inflammatory activity than AN1284 in LPS-activated macrophages and in mice. Maximal reductions in IL-6 in plasma, brain and liver were seen after subcutaneous injection of (0.5 mg/kg). This dose was also most effective in reducing IL-6 in the liver after oral drug administration but 2.5 mg/kg was needed for the same reductions in plasma and brain. Peak concentrations after oral administration of AN1284 (2.5 mg/kg) were 5.5-fold higher in the liver but 7-, 11 and 19-fold lower in plasma, brain and kidneys than after injection of 0.5 mg/kg. Similar concentrations in the liver were achieved by AN1284 (1 mg/kg/day) administered in the drinking fluid, and 2.5 mg/kg/day, via subcutaneously-implanted mini-pumps. Although drug levels were only 12% of the peak seen after acute injection of 0.5 mg/kg, they significantly decreased hepatocellular damage, liver triglycerides and cholesterol in diabetic mice. Conclusion. AN1284 can be given orally to treat chronic liver disease and its preferential concentration in the liver should limit potential adverse effects.