Opioid analgesics are drugs that relieve pain by binding to opioid receptors on nerves and preventing pain signals from traveling through the nervous system. These drugs bind mainly to receptors in the digestive system and the brain. Some opioid analgesics occur naturally in plants, but some have been synthetically modified or created by scientists. Each opioid drug has a different effect on pain receptors, and some are less effective than others.
Natural opioid analgesics are derived from the opium poppy. This poppy is found in Asia and Europe and has been used for thousands of years for its exceptional ability to both relieve pain and increase tolerance to it. Compounds containing these substances have likely been used to perform surgery on patients and to relieve the pain associated with serious injuries or illnesses since before written history.
In modern medicine, the various alkaloids present in opium have been extracted and are often used independently or in conjunction with other medications. Two of the most commonly used opioid alkaloids are morphine and codeine. These chemicals are present in unrefined opium at varying levels depending on the specific opium poppy.
Medical advancements have also led to the creation of partially synthetic opioid analgesics. These medications include oxycodone and heroin. They are created by taking the alkaloids that have been separated from opium and chemically altering them. The chemical alterations can make these semi-synthetic opioid analgesics more effective than natural opioids.
There are also completely synthetic opioid analgesics. These drugs can be used for pain relief, though they are not usually as strong as the opioids that are made from natural sources of opium. Commonly used synthetic opioids include pethidine, which is used to relieve pain during labor.
All types of opioid analgesics have the potential to be abused. They are addictive and quickly create both a physical and psychological dependence. Over time, a person can become habituated to the use of opioid analgesics, which means that more of the drug is needed in order to achieve the same effects. Most of the time, hospitals administer these medications for only a short amount of time. Terminally ill patients, however, may be given as much medication as they need in order to relieve the pain.