Influence of Uric Acid on Photostability of Sulfathiazole Sodium Solutions

Abstract The effect of uric acid as a photoprotective agent for buffered and unbuffered solutions of sulfathiazole sodium was investigated. Uric acid solution in glycerin was found to enhance the photostability of sulfathiazole sodium solutions. The higher the concentration of uric acid used, the greater was its photoprotective action within the concentration range studied. Uric acid was also found to demonstrate its photoprotective effect in the presence of either sodium sulfite or EDTA. Sodium sulfite alone in a concentration of 0.1% produced a detrimental effect on the photostability of sulfathiazole sodium in either borate or phosphate buffer of pH 9 ± 0.2. From the standpoint of the overall chemical stability of sodium sulfathiazole, uric acid appeared to be most effective when used alone in the borate buffer. However, the incorporation of 0.1% sodium sulfite in addition to uric acid contributed to the prevention of discoloration in either the borate or the phosphate buffer.