Methadone is a powerful synthetic opiate used to treat moderate to severe pain. It also is considered the standard of treatment as an opiate replacement therapy for heroin addiction. It is about as strong as morphine, but lasts much longer, ranging from 24 to 36 hours. It was first approved for medical use in the United States by the Food and Drug Administration in 1947. According to Drugs.com some of the more common side effects of methadone include drowsiness and insomnia, nausea, vomiting, itching, sweating and constipation.
Drowsiness and Insomnia
A patient taking methadone may experience drowsiness and insomnia depending on the dose and the length of time they have been adjusted to opiates. Because methadone lasts an average of 24 to 36 hours, its effects usually are felt throughout the day, in contrast to other short-acting opiates like morphine. Users may experience drowsiness because methadone acts directly as a central nervous system depressant. This is why the National Highway Traffic Safety Administration states that it can have serious and dangerous effects on a person's driving ability. The insomnia associated with methadone can be related to how opiates inhibit the release of adenosine, a neurotransmitter essential for the body to initiate sleep. In the December 2009 issue of Anethesiology, Dr. Max Kelz states that this offset of adenosine can put opiate patients in a state of sleep-and-wake limbo.
Nausea and Vomiting
Methadone also is known to cause gastronomical upsets. A methadone user may experience nausea, which can lead to vomiting if it does not subside. As users become more adjusted to methadone and subsequently find the optimal dose, the nausea usually becomes less severe. Methadone specifically binds to the mu opioid receptor, and is directly related to paralysis in the stomach and intestines. The nausea associated with methadone may also stem from changes in brain activity. Dr. Gerald Bennett and associates state in the The Methadone Briefing that methadone can trigger the chemoreceptive trigger zone, a part of the brain responsible for initiating vomiting and repulsion.
Itching and Sweating
Another common side effect of opiates is the onset of itching and sweating. Several mechanisms take place that may be responsible. The primary cause of itching and sweating may be a release of histamine caused by the methadone. The Royal Children's Hospital of Melbourne states that when the body encounters a possible threat, certain body cells activate and rupture, releasing histamine, and therefore resulting in itching and sweating. Mild opiate blockers may be used to counteract this response, but this also may weaken the initial pain killing effect of the methadone. Increased sweating also may be related methadone's effect on core body temperature.
Constipation
Constipation is another common and unwanted side effect related to the use of methadone. According to The Methadone Briefing, the contractions in the intestines are virtually seized by methadone and it may take an additional 12 hours before defecation occurs. In addition, the anal sphincter becomes contracted by the use of methadone, increasing the difficulty to complete a bowel movement. Methadone is so adept at causing constipation, it is usedsometimes to treat the most severe intestinal infections, such as dysentery. Although the constipation induced by methadone usually is not a major health threat, it can be remedied easily with increases in fiber, fluid intake and regular exercise.
