Gentisic acid: a new stabilizer for low tin skeletal imaging agents: concise communication

In vitro stabilization of low-tin bone-imaging agents has previously been achieved with ascorbic acid. In this study gentisic acid is shown to be an equally effective antioxidant for the (1-hydroxyethylidene) diphosphonate (HEDP) and hydroxymethylenediphosphonate (HMDP) skeletal agents. In vitro studies show less than 2% free sodium [/sup 99m/Tc] pertechnetate at 24 h with the gentisic acid stabilizer. Studies in guinea pigs at 3 and 24 h - whether with C-14- or H-3-labeled gentisic acid as stabilizer - show no alteration in the biodistribution of either skeletal imaging agent by the addition of the gentisic acid. Gentisic acid is a safe and effective stabilizer, and clinical studies have shown bioequivalency with ascorbic acid