Among the most prominent psychoactive alkaloids found in opium are morphine, codeine, and thebaine. Morphine is the most abundant alkaloid, typically comprising 8 to 17 percent of the dry weight of opium, though specially bred cultivars can yield up to 26 percent. This powerful analgesic interacts with opioid receptors in the body, primarily altering the perception of pain. Codeine is another significant alkaloid, used to suppress coughs and provide relief for mild to moderate pain. Thebaine, while not directly used as a pain reliever, serves as a precursor in the synthesis of other pharmaceutical opioid drugs like oxycodone and hydrocodone.