Hydromorphone, a more common synonym for dihydromorphinone (not to be confused by dihydromorphine, which is a different derivative of the morphine family), commonly a hydrochloride (brand names Palladone, Dilaudid, and numerous others) is a very potent centrally acting analgesic drug of the opioid class. It is a derivative of morphine; to be specific, a hydrogenated ketone thereof, and it can be said that hydromorphone is to morphine as hydrocodone is to codeine and, therefore, a semi-synthetic drug. It is in medical terms an opioid analgesic and in legal terms a narcotic. Hydromorphone is commonly used in the hospital setting, mostly intravenously (IV) because its bioavailability orally, rectally, and intranasally is very low. Sublingual administration is usually superior to swallowing for bioavailability and effects.