Description Pyridoxine hydrochloride is HCl salt of pyridoxine or vitamin B6. It is a water-soluble vitamin which plays an important role in the treatment of roughness, sunburn, acne, and itch of the skin.Pyridoxine-(methyl-d3) hydrochloride is a deuterated vitamin B6 wherein C-2 methyl protons are replaced by deuterium.Pyridoxine-(methyl-d3) hydrochloride can be used as a stable isotope internal standard for accurate data interpretation in specific biological samples.