“Methylene blue (CAS 61-73-4, MB), a guanylyl cyclase and/or NO synthase inhibitor, was … and nociceptive at 5 and 40 mg/kg doses, respectively, 5 mg/kg dose of MB significantly increased the antinociceptive effect of pyridoxine , but did not change it at 40 mg/kg dose.”
“On the other hand, pyridoxine significantly decreased the antinociceptive effect of MB and reversed the MB-induced nociception to antinociception.”