Hydrocodone or dihydrocodeinone is a semi-synthetic opioid derived from either of two naturally occurring opiates-codeine and thebaine. Hydrocodone is an orally active narcotic analgesic (pain reliever) and antitussive (cough suppressant). It is commonly available in tablet, capsule, and syrup form, and is often compounded with other, generally less effective non-opioid compounds such as paracetamol (also known as acetaminophen) or ibuprofen, often added both to discourage recreational use (as paracetamol can cause potentially fatal liver toxicity at high doses), and to provide a possible synergy of analgesic effects between hydrocodone and the non-opioid compounds present. However, the effectiveness and safety of hydrocodone compound products versus hydrocodone-only products remains a highly debated issue. The particular niche in which hydrocodone is most commonly used is as an intermediate centrally acting analgesic and strong cough suppressant, especially in those for whom histamine release and attendant itching from codeine is a problem. For the latter indication, at the 5 to 10 mg dose range hydrocodone is more powerful than most cough suppressants, being roughly equal to its derivative dihydrocodeinone enol acetate, with the top of the list being morphine and hydromorphone and methadone (methadone linctus, about 33 percent the concentration of the liquid used for opioid physical dependence maintenance or detoxification) and dihydrocodeine being right below. The experiments in dogs conducted by Winder and Rosière in the mid-1950s reported in the Journal of Pharmacology in 1955 indicate that hydrocodone is 12 times stronger than codeine as an antitussive (morphine 14×, methadone 9×), and other tests from 1920 forward showed it was about six times stronger as an analgesic.