Thirty minutes after the injection of 500μg of riboflavin-5'-monosulfate to a rat, riboflavin-5'-monosulfate was proved to be emigrated into the liver, heart, kidney and intestine. However, riboflavin-5'-monosulfate could not be easily exchanged for physiological flavin compounds, i. e., FAD, FMN or riboflavin. Injected riboflavin-5'-monosulfate was rapidly excreted into urine.
