Morphine and Codeine are natural opiate used to treat pain. When people become addicted to these drugs, they often times turn to another more potent natural opiate, Heroin. In the last decade, people have turned to synthetic man made opiates like Oxycoden which is 1.5 times more powerful than Morphine.
The newest player in the world of synthetic opates, Fentanyl, is said to be 50-100 times more potent than morphine and 30 to 50 times stronger than Heroin.