Stability of flavone-8-acetic acid (LM975) in aqueous solutions by high-performance liquid chromatography.

A high-performance liquid chromatographic method has been developed to investigate the stability of solutions of flavone-8-acetic acid (LM975) during preparation and storage. LM975 (20 microg ml(-1) in PBS) was found to be completely stable for 10 days at 80 degrees C as long as light was rigorously excluded. The drug showed no significant adsorption to containers of different materials or to two filtration units tested. Drug degradation did occur however, on exposure to light. In normal laboratory light the t(0.95) (5% degraded) was 30.3 min, in intense natural light (laboratory window sill) the t(0.95) was 3.3 min and in intense artificial light (100 W bulb at 10 cm) the t(0.95) was 13.8 min. NMR and mass spectral analysis of the isolated degradation product implied the formation of the decarboxylated product, 8-methyl flavone. It is suggested that care be taken to exclude light during the preparation, storage and infusion of solutions of flavone-8-acetic acid.