title: Absence of evidence of biotransformation of morphine to codeine in man.
mesh_terms: D001711:Biotransformation; D002849:Chromatography, Gas; D002855:Chromatography, Thin Layer; D003061:Codeine / Q000096:biosynthesis / Q000652:urine*; D006801:Humans; D009020:Morphine / Q000378:metabolism* / Q000652:urine
chemical_list: D009020:Morphine; D003061:Codeine