 Being the prototype of the entire opioid class of drugs means that morphine has properties that may lend it to misuse.Morphine addiction is the model upon which the current perception of addiction is based.Animal and human studies and clinical experience back up the contention that morphine is one of the most euphoric drugs known, and via all but the IV route heroin and morphine cannot be distinguished according to studies because heroin is a prodrug for the delivery of systemic morphine.