Molecular model of oxycontin. It's molecular formula is C18 H21 NO4, and the molecular mass is 315.364 g/mol. Also called oxycodone, Oxycontin is an opioid analgesic medication synthesized from opium-derived thebaine. It was developed in 1916 in Germany as one of several new semi-synthetic opioids in an attempt to improve on the existing opiates and opioids: morphine, diacetylmorphine (heroin), and codeine. It is best known as the main active ingredient in a number of oral medications commonly prescribed for the relief of moderate to severe pain. It is addictive and has become widely abused as a recreational drug. Color Key: Carbon- blue-grey, Hydrogen- yellow, Nitrogen- not shown, Oxygen- red.