Riboflavin as an antinociceptive and anti-inflammatory adjuvant

Riboflavin is a B vitamin that has been used in the prophylactic treatment ofmigraine. Previously, we have reported that it is able to produce antinociceptive action intwo preclinical models, thermal hyperalgesia and formalin tests, as well as, antiinflammatoryactivity in the paw edema model, all of them in the rat. However, it is notable to produce any effect in models of neuropathic pain. In order to establish if this drugmay be useful as adjuvant in the treatment of pain and inflammation, we evaluatedcombinations of several analgesic and anti-inflammatory drugs with riboflavin in twoexperimental models, thermal hyperalgesia and paw edema models. Drugs evaluated inthe thermal hyperalgesia model were tramadol, metamizole, ketoprofen, ketorolac,meloxicam, diclofenac and acetaminophen. Dose response curves were constructed forall these drugs and riboflavin and several combinations were tested in order to carry outisobolographic analyses. Riboflavin was able to potentiate the antinociceptive activity ofmost of the drugs tested. On the other hand, drugs tested in the paw inflammation modelwere ketoprofen, meloxicam and nimesulide. Riboflavin was also able to potentiate theanti-inflammatory action of ketoprofen and meloxicam, but not of nimesulide, in whichadditive effect was observed. These results indicate that riboflavin is able to potentiate a wide variety of analgesic and anti-inflammatory drugs, suggesting that this drug has potential as an adjuvant in the treatment of pain and inflammation.