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Methylnaltrexone (By injection)

Treats constipation caused by narcotic pain medicines.

What works?

Learn more about the effects of these drugs. The most reliable research is summed up for you in our featured article.

Methylnaltrexone injection is used to treat constipation caused by opioids (narcotic pain medicines), in adults with long-lasting pain that is not caused by cancer or adults with advanced illness. This medicine is used when other medicines for constipation (laxatives) have not worked well. This medicine is available only with your doctor's prescription… Read more
Brand names include
Relistor
Drug classes About this
Gastrointestinal Agent

What works? Research summarized

Evidence reviews

Laxatives for the management of constipation in people receiving palliative care

People with an incurable illness may receive palliative care, which involves making the person as comfortable as possible by controlling pain and other distressing symptoms. People receiving palliative care commonly experience constipation. This is as a result of the use of medicines (e.g. morphine) for pain control, as well as disease, dietary and mobility factors. There is a wide range of laxatives available. The aim of this review was to determine what we know about the effectiveness of laxatives for the management of constipation in people receiving palliative care.

Treatments for Constipation: A Review of Systematic Reviews [Internet]

Constipation has many definitions and is often described differently depending on the population queried. Physicians may define constipation as a reduction in the frequency of bowel movements to fewer than three times per week while patients identify more with the symptoms associated with constipation such as difficulty passing stool, hard stool consistency, feelings of abdominal cramping, and feelings of incomplete stool passage. Causes of constipation may be primary (idiopathic) or secondary to other factors such as diet, medication, or medical conditions. Constipation can affect anyone as a minor annoyance but up to a quarter of the population experiences it chronically or severely. It can substantially affect quality of life and be debilitating. It is estimated that between 2% to 27% of the population are affected depending upon the definition of constipation used.

Mu‐opioid antagonists in the treatment of bowel dysfunction as a result of previous treatment by opioids

There is insufficient evidence to show that new opioid antagonists are effective in treating constipation due to strong analgesics. Opioids (morphine‐like drugs) are substances used to treat severe pain. They cause many side effects, and frequently affect the stomach and bowels. Opioid‐induced bowel dysfunction (OBD) is a recently coined term used to describe constipation, incomplete evacuation of the bowels, bloating, and increased reflux of stomach contents. OBD occurs both with short and long term use of opioids, in patients with many types of diseases, and causes increased disease and reduced quality of life. Traditional opioid antagonists (drugs that block the receptors which opioids bind to) can be used to reverse many of the side effects of opioids, including constipation, but because they block opioid receptors in the brain, they may also reverse reduction of pain. The search for opioid antagonists that act only in the gut ("peripherally active" antagonists), therefore not reversing reduction of pain, has produced two new drugs, methylnaltrexone and alvimopan, which are at an advanced phase of development. There is not enough information to make firm conclusions about the safety or effectiveness of traditional opioid antagonists in the treatment of OBD. Alvimopan and methylnaltrexone both show promise in treating OBD, but further data will be required to fully assess their effectiveness.

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Summaries for consumers

Laxatives for the management of constipation in people receiving palliative care

People with an incurable illness may receive palliative care, which involves making the person as comfortable as possible by controlling pain and other distressing symptoms. People receiving palliative care commonly experience constipation. This is as a result of the use of medicines (e.g. morphine) for pain control, as well as disease, dietary and mobility factors. There is a wide range of laxatives available. The aim of this review was to determine what we know about the effectiveness of laxatives for the management of constipation in people receiving palliative care.

Mu‐opioid antagonists in the treatment of bowel dysfunction as a result of previous treatment by opioids

There is insufficient evidence to show that new opioid antagonists are effective in treating constipation due to strong analgesics. Opioids (morphine‐like drugs) are substances used to treat severe pain. They cause many side effects, and frequently affect the stomach and bowels. Opioid‐induced bowel dysfunction (OBD) is a recently coined term used to describe constipation, incomplete evacuation of the bowels, bloating, and increased reflux of stomach contents. OBD occurs both with short and long term use of opioids, in patients with many types of diseases, and causes increased disease and reduced quality of life. Traditional opioid antagonists (drugs that block the receptors which opioids bind to) can be used to reverse many of the side effects of opioids, including constipation, but because they block opioid receptors in the brain, they may also reverse reduction of pain. The search for opioid antagonists that act only in the gut ("peripherally active" antagonists), therefore not reversing reduction of pain, has produced two new drugs, methylnaltrexone and alvimopan, which are at an advanced phase of development. There is not enough information to make firm conclusions about the safety or effectiveness of traditional opioid antagonists in the treatment of OBD. Alvimopan and methylnaltrexone both show promise in treating OBD, but further data will be required to fully assess their effectiveness.

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