Drugs such as morphine, codeine, and oxycodone as well as heroin and fentanyl are classified as opioids. Opioids can be further classified by their synthetics process into natural, semi-synthetic, and synthetic opioids.
Examples of natural opioids include morphine, codeine, thebaine, and papaverine. Drugs that fall into this category are derived directly from the poppy plant and are also known as opiates.
Drugs such as buprenorphine and oxycodone are considered semi-synthetic opioids. These types of opioids are man-made and are often used in clinical medicine. Heroin also falls into this category of opioids.
Fentanyl and methadone are the most common forms of synthetic opioids. Drugs classified as synthetic opioids are manufactured in laboratories to have a similar chemical structure to natural opioids.