An opiate is a narcotic analgesic that contains either natural or synthetic opium and is most often used medically to alleviate pain. Natural opium is extracted from the seed pod of the poppy plant in Asia. Drugs containing natural or synthetic opium are only legally available by prescription--however, they can be illegally purchased on the street. Opiate drugs are both physically and psychologically addictive when used in high doses for a long period of time. The misuse of opiates is associated with a high risk of accidental drug overdose.
Types of Opiates
Naturally occurring opiates are morphine and codeine. Semi-synthetic or opioids include heroin, hydrocodone, hydromorphone (Dilaudid), meperidine (Demerol) and oxycodone (Percodan). Synthetic opiods include fentanyl (Sublimaza), methadone (Dolophine), propoxyphene (Darvon) and pentazocine (Talwin). All opiate drugs have similar effects to varying degrees.
Morphine is derived from the opium poppy or papaver somniferum. Codeine can also be extracted from the poppy plant, but most often it is synthesized from morphine. Morphine is powerful narcotic analgesic and is highly addictive. The only opiate more addictive is heroin. Morphine can be given to a person orally or it can be smoked, injected or sniffed. Morphine may be prescribed to alleviate pain, help with breathing problems, or to treat diarrhea.
Semi-Synthetic and Synthetic Opiates
The opiates known as codeine, hydrocodone and oxycodone are synthesized from morphine. The potential for addiction is less with codeine than morphine or hydrocodone. Meperifine, fentanyl, propoxyphene, pentazocine, heroin and methadone are entirely synthetic and can be made from dichlorodiethyl and benzyl cyanide. Heroin is the most addictive opiate drug and can lead to many health problems such heart infections, kidney disease, liver disease, and possibly overdose death. Methadone is used as a replacement for opiate drugs when patients in rehab are withdrawing.
Opiates alleviate pain, but they may also produce a euphoric feeling. Side effects may include sleepiness, concentration difficulties, blurry vision, poor night vision, slowed breathing and slight anxiety. Stomach side effects may include nausea, vomiting, constipation and poor appetite.
Opiate Addiction and Withdrawl
Individuals using opiate drugs may become both psychologically and physically addicted to the drugs in as little as two weeks.Opiates can also cause allergic reactions, some severe. Signs of this include itching, swelling, dizziness, rash and labored breathing. Side effects depend on the many factors including dose, previous exposure to opiates and the method by which users consume the drug. Recreational users may take opiates in a manner in which they are not prescribed to achieve a “high” or rush. Most often, this can include chewing, breaking or crushing the drug and taking it orally or injecting it. Opiate-tolerant patients may take a particular drug more frequently or in higher doses than prescribed to achieve pain relief. Both of these scenarios can lead to severe side effects, dependence and addiction. Opiate addiction is recognized as a central nervous system disorder, caused by continuous opiate intake.
After prolonged opiate use, the nerve cells in the brain, which would otherwise produce endogenous opiates (natural painkillers, or endorphins), cease to function normally. The body stops producing endorphins because it is receiving opiates instead. The degeneration of these nerve cells causes a physical dependency to an external supply of opiates. Abrupt or sudden abstinence from opiates induces yet another traumatic disorder withdrawl syndrome. In addition, psychological withdrawal may include mood swings, depression and increased sensitivity to pain. Withdrawal is a long and painful process, which can cause permanent damage to your heart lungs, and brain. For health compromised patients, untreated and unmonitored withdrawal can lead to death. Opiate dependency treatment requires safe and responsible medical care. Individuals withdrawing from an opiate often feel like they have a severe case of the flu. Substance abuse is a major health concern in the United States, with annual treatment costs in the billions of dollars. It is also a social ill manifested in family problems, lost productivity, and crime. Heroin, an opiate drug, has been viewed as a key player in this rapidly growing drug-dependent segment of society. While the number of heroin dependance is increasing at an alarming rate, a previously unrecognized opiate dependence based on prescription medications (opiates, narcotics) is moving to the forefront.
Chronic pain sufferers, surgical patients, sickle-cell patients, and cancer patients seeking relief from pain are prescribed pain medication by their physicians and subsequently become dependent. These people are not "drug addicts" in the stereotypical sense, but people with real medical conditions who find themselves in the same situation as drug addicts. In fact, so addictive are these opiate-based pain medications that despite fully understanding the medications' addictive nature, ten percent of physicians are themselves dependent on the very drugs they prescribe, according to the Council of Emergency Medicine Residency Directors (CORD).
Opiates in the Human Body
Opiates elicit their powerful effects by activating opiate receptors that are widely distributed throughout the brain and body. Once an opiate reaches the brain, it quickly activates the opiate receptors that are found in many brain regions and produces an effect that correlates with the area of the brain involved.
Two important effects produced by opiates, such as morphine, are pleasure (or reward) and pain relief. The brain itself also produces substances known as endorphins that activate the opiate receptors. Research indicates that endorphins are involved in many things, including respiration, nausea, vomiting, pain modulation, and hormonal regulation.
When opiates are prescribed by a physician for the treatment of pain and are taken in the prescribed dosage, they are safe and there is little chance of addiction.
However, when opiates are abused and taken in excessive doses, addiction can result.
Opiate: Reward System
Findings from animal research indicate that, like cocaine and other abused drugs, opiates can also activate the brain's reward system. When a person injects, sniffs, or orally ingests heroin (or morphine), the drug travels quickly to the brain through the bloodstream.
Once in the brain, the heroin is rapidly converted to morphine, which then activates opiate receptors located throughout the brain, including within the reward system.
Because of its chemical structure, heroin penetrates the brain more quickly than other opiates, which is probably why many addicts prefer heroin.
Within the reward system, the morphine activates opiate receptors in the VTA, nucleus accumbens, and cerebral cortex (refer to the Introduction for information on the reward system). Research suggests that stimulation of opiate receptors by morphine results in feelings of reward and activates the pleasure circuit by causing greater amounts of dopamine to be released within the nucleus accumbens. This causes an intense euphoria, or rush, that lasts only briefly and is followed by a few hours of a relaxed, contented state. This excessive release of dopamine and stimulation of the reward system can lead to addiction.
Opiates also act directly on the respiratory center in the brainstem, where they cause a slowdown in activity. This results in a decrease in breathing rate. Excessive amounts of an opiate, like heroin, can cause the respiratory centers to shut down breathing altogether. When someone overdoses on heroin, it is the action of heroin in the brainstem respiratory centers that can cause the person to stop breathing and die.
Opiate, Brain and Endorphin
As mentioned earlier, the brain itself produces endorphins that have an important role in the relief or modulation of pain. Sometimes, though, particularly when pain is severe, the brain does not produce enough endorphins to provide pain relief. Fortunately, opiates, such as morphine are very powerful pain relieving medications. When used properly under the care of a physician, opiates can relieve severe pain without causing addiction.
Although endorphins are not always adequate to relieve pain, they are very important for survival. If an animal or person is injured and needs to escape a harmful situation, it would be difficult to do so while experiencing severe pain. However, endorphins that are released immediately following an injury can provide enough pain relief to allow escape from a harmful situation. Later, when it is safe, the endorphin levels decrease and intense pain may be felt. This also is important for survival. If the endorphins continued to blunt the pain, it would be easy to ignore an injury and then not seek medical care.
There are several types of opiate receptors, including the delta, mu, and kappa receptors. Each of these three receptors is involved in controlling different brain functions. For example, opiates and endorphins are able to block pain signals by binding to the mu receptor site. The powerful new technology of cloning has enabled scientists to copy the genes that make each of these receptors. This in turn is allowing researchers to conduct laboratory studies to better understand how opiates act in the brain and, more specifically, how opiates interact with each opiate receptor to produce their effects. This information may eventually lead to more effective treatments for pain and opiate addiction.
Opiates: Pain Relief
Feelings of pain are produced when specialized nerves are activated by trauma to some part of the body, either through injury or illness. These specialized nerves, which are located throughout the body, carry the pain message to the spinal cord. After reaching the spinal cord, the message is relayed to other neurons, some of which carry it to the brain. Opiates help to relieve pain by acting in both the spinal cord and brain. At the level of the spinal cord, opiates interfere with the transmission of the pain messages between neurons and therefore prevent them from reaching the brain. This blockade of pain messages protects a person from experiencing too much pain. This is known as analgesia.
Opiates also act in the brain to help relieve pain, but the way in which they accomplish this is different than in the spinal cord.
There are several areas in the brain that are involved in interpreting pain messages and in subjective responses to pain. These brain regions are what allow a person to know he or she is experiencing pain and that it is unpleasant. Opiates also act in these brain regions, but they don't block the pain messages themselves. Rather, they change the subjective experience of the pain. This is why a person receiving morphine for pain may say that they still feel the pain but that it doesn't bother them anymore.
- From the National Institute on Drug Abuse