Animal experiment:

Rats: Riboflavin tetrabutyrate-14C (700 μg, corresponding to 400 μg of riboflavin; total radioactivity 2.19×105 cpm) is suspended in 0.2mL of soybean oil and given per os . In the case of injection, same amount of Riboflavin tetrabutyrate-14C is dissolved in 1mL of soybean oil and injected subcutaneously into the back of rat[3].

Riboflavin is an easily absorbed micronutrient with a key role in maintaining health in humans and other animals.Target: OthersRiboflavin (vitamin B2) is the direct precursor of redox enzyme cofactors flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are essential for multiple cell physiology [1]. Urinary excretion of riboflavin contributes to one-half of the overall removal of riboflavin from plasma. No sex differences were observed for any of the pharmacokinetic variables (P > 0.05) [2]. Riboflavin, similar to other vitamins of the B complex, presents anti-inflammatory activity but its full characterization has not yet been carried out. Riboflavin (25, 50 or 100 mg/kg, i.p.), administered immediately and 2 h after the injection of carrageenan, induced antiedema and antinociceptive effects. The antinociceptive effect was not inhibited by the pretreatment with cadmium sulfate (1 mg/kg), an inhibitor of flavokinase. Riboflavin (50 or 100 mg/kg, i.p., 0 and 2 h) also inhibited the fever induced by lipopolysaccharide (LPS) in rats. Riboflavin is a safe drug, is approved for clinical use and exacerbates the antinociceptive effect of morphine, may warrant clinical trials to assess its potential in the treatment of different painful or inflammatory conditions [3].

References:
[1]. Long, Q., et al., Riboflavin biosynthetic and regulatory factors as potential novel anti-infective drug targets. Chem Biol Drug Des, 2010. 75(4): p. 339-47.
[2]. Zempleni, J., J.R. Galloway, and D.B. McCormick, Pharmacokinetics of orally and intravenously administered riboflavin in healthy humans. Am J Clin Nutr, 1996. 63(1): p. 54-66.
[3]. Bertollo, C.M., et al., Characterization of the antinociceptive and anti-inflammatory activities of riboflavin in different experimental models. Eur J Pharmacol, 2006. 547(1-3): p. 184-91.