All About Opioids and Opioid-Induced Constipation (OIC)
 About Opioids | Symptoms of OIC | Resources |
| Causes of OIC | Treatment for OIC | |
| Palliative Care Facts | Glossary of Terms |
About Opioids
What are opioids?
Opioids are a class of drugs that are commonly prescribed for their analgesic, or pain-killing, properties. They include substances such as morphine, codeine, oxycodone, and methadone. Opioids may be more easily recognized by drug names such as Kadian, Avinza, OxyContin, Percodan, Darvon, Demerol, Vicodin, Percocet, and Lomotil.
Opioids may be classified as natural, semi-synthetic, fully synthetic, or endogenous. Natural opioids such as codeine and morphine are derived from opiate alkaloids contained in the resin of the opium poppy. Semi-synthetic opioids such as oxycodone and hydrocodone are created by chemically altering the natural opioids. Fully synthetic opioids such as methadone are synthesized from non-opioid substances in laboratories. Endogenous opioids are naturally produced by the body and include substances such as endorphins.
How do opioids work?
Opioids bind to specific proteins called opioid receptors that are located in the brain, spinal cord, and gastrointestinal tract. Through this mechanism, opioids are able to block the brain's ability to perceive pain. Instead, opioids tend to stimulate the pleasure centers of the brain, inducing euphoria.
* Image borrowed from Wyeth library
* Image borrowed from Wyeth library
When are opioids used?
Opioids are used in medicine because they can block the perception of pain. Patients receiving palliative care frequently report pain as one of the most distressing factors as they approach the end of life. About 70% of patients with advanced cancer and 65% of patients dying from other non-malignant diseases commonly complain of pain 1. Opioid-based medicines are prescribed to these patients to reduce their pain and increase their quality of life. The vast majority of patients receiving long-term opioid pain medication are in advanced stages of their disease.
* Image borrowed from Wyeth library
What are side effects of opioids?
Opioid use carries several side effects. These include drowsiness, nausea, slower breathing, and a general depression of the respiratory system. Further, opioids often cause constipation, or opioid-induced constipation (OIC). OIC is an uncomfortable side-effect that occurs in many patients who receive opioid treatments to relieve pain.
Causes of Opioid-Induced Constipation (OIC)
What is constipation?
Constipation can be defined as a decrease in the frequency of passing formed stools. The condition also may be characterized by stools that are hard and difficult to pass.
What causes constipation?
Constipation may be the result of inadequate fiber intake, inadequate fluid intake, or a lack of physical activity. It may also be caused by disease or ailments such as diabetes, intestinal obstruction, spinal cord compression, excessive calcium levels, a lack of potassium, or kidney problems. A third cause of constipation is pharmacologically based. That is, constipation is a side-effect of drugs that are used to treat various diseases and pain, such as the opioids given to cancer patients.
How do opioids cause constipation?
Opioids are effective pain relievers, but often have the side effect of constipation. These medicines affect the gastrointestinal tract in a variety of ways. Opioids increase the amount of time it takes stool to move through the gastric system. They increase nonpropulsive contractions in the middle of the small intestine (jejunum) and decrease longitudinal propulsive peristalsis - motions critical to moving food through the intestines. This results in food that fails to travel through the digestive tract. Opioids are also able to partially paralyze the stomach (gastroparesis) so that food remains in the digestive organ for a longer period of time. Additionally opioids reduce digestive secretions and decrease the urge to defecate.
* Image borrowed from Wyeth library
All About Opioids and Opioid-Induced Constipation (OIC)
| About Opioids | Symptoms of OIC | Resources |
| Causes of OIC | Treatment for OIC | |
| Palliative Care Facts | Glossary of Terms |
Facts about Palliative Care
What is palliative care?
According to the World Health Organization, palliative care can be defined as:
"An approach that improves the quality of life of patients and their families facing the problems associated with life-threatening illness, through the prevention and relief of suffering by means of early identification and impeccable assessment and treatment of pain and other problems, physical, psychosocial and spiritual".1
One goal of palliative care is for the patients and families to accept dying as a normal process. It seeks to provide relief from pain and uncomfortable symptoms while integrating psychological and spiritual features of patient care. Palliative care strives to offer a support system to help patients live their remaining time as actively as they can and to help families bereave and deal with the illness of a loved one.2
Since pain is the most visible sign of distress among patients receiving palliative care, affecting about 70% of cancer patients and 65% of patients dying from non-malignant diseases, opioids are a very common treatment option 3. These medicines form part of well-established treatment plans for managing pain as well as several other symptoms that patients encounter. Often, opioids are chosen during palliative care in spite of the side effects such as drowsiness, nausea, vomiting, and constipation.
Some type of palliative care is given to 45,000 new patients each year in England, Wales, and Northern Ireland. About 90% of these patients have cancer, while the remaining patients have heart disease, stroke, motor neuron disease, or multiple sclerosis. The providers of the palliative care include in-patient care, hospital support services, community care, day care and outpatient care.4
Symptoms of OIC
What symptoms are associated with OIC?
Several physical and other symptoms are prevalent in sufferers of opioid-induced constipation (OIC). Physicians usually will gather patient history information to check for standard problems associated with constipation such as too little fiber and fluid intake, too little exercise, underlying medical problems, and current medications. Be prepared for a physical assessment that requires oral, abdominal, and digital anorectal examinations.
Common physical symptoms of OIC include:
- Stools that are hard and dry
- Difficulty such as straining, forcing, and pain when defecating
- A constant feeling that you need to use the toilet
- Bloating, distention, or bulges in the abdomen
- Abdominal tenderness
Other symptoms of OIC include:
- Feeling and being sick
- Tiredness and lethargy
- Appetite loss
- Feeling depressed
Treatment for OIC
Treatment options for OIC
Although opioids are very effective for treating and managing pain, their use frequently results in opioid-induced constipation (OIC). Treatment options for OIC may be as simple as changing diet or as complicated as requiring several medicines and laxatives.
How can changing lifestyle factors treat OIC?
Changing lifestyle factors is usually the first recommendation that physicians make for the prevention or treatment of constipation. This includes:
- Increasing dietary fiber
- Increasing fluid intake
- Increasing exercise or physical activity
- Increasing time and privacy for toileting
Changes in lifestyle, however, may not be possible for many patients. In addition, these changes may be ineffective in treating OIC. If there is a concurrent underlying disease or medicine that is causing constipation, the disease may need to be treated separately or another treatment regimen may have to be considered.
What drugs or medicines treat OIC?
OIC treatment usually requires additional medicines to be prescribed along with the opioid painkillers that are causing the constipation. Withholding the opioid treatment is ill-advised because it results in a decrease in the patient's quality of life. Often, laxatives and/or cathartics are prescribed at the same time as the opioid painkillers so that treatment for the constipation beings immediately. A cathartic accelerates defecation, while a laxative eases defecation, usually by softening the stool; some medicines are considered to be both laxatives and cathartics.
For the treatment of OIC, doctors may prescribe:
- Osmotic laxatives - increase the amount of water in the gut, increasing bulk and softening stools.
- Emollient or lubricant cathartics - soften and lubricate stools.
- Bulk cathartics - increase bulk and soften stools.
- Stimulant cathartics - directly counteract the effect of the opioid medications by increasing intestinal motility, helping the gut to push the stools along.
- Prostaglandins or prokinetic drugs - change the way the intestines absorb water and electrolytes, and they increase the weight and frequency of stools while reducing transit time.
- Other medicines block the effects of opioids on the bowel to reverse opioid-induced constipation.
Although the treatments listed above are usually successful in treating OIC, sometimes a physician will recommend rectal intervention. As discussed, prophylaxis with laxatives are/or cathartics is considered usual - as some clinicians assume [constipation] to be virtually universal in patients who are prescribed opioid analgesics1.
Rectal interventions are indicated if the appropriate oral measures have been ineffective2. Rectal intervention means the following treatments:
- Suppositories
- Enemas (micro and larger volume)
- Rectal irrigation (sometimes known as colonic irrigation)
- Manual evacuation
The first choice rectal intervention for uncomplicated constipation is glycerine suppositories2. If these are ineffective, then a stimulant enema might be administered. Oral and rectal stimulant laxatives should be avoided if there is possible or proven bowel obstruction. Gentle rectal measures can sometimes be effective in emptying the rectum and lower colon. Oral softening agents are useful if the obstruction is incomplete. It should be remembered that constipation can cause bowel obstruction.
If none of the rectal laxatives above prove adequate to remove impacted faeces, rectal irrigation with normal saline can be performed3. Manual evacuation should be used as a last resort when all other methods of bowel management have been shown to be ineffective.
Combination therapy
Constipation is a known side effect of opioid analgesics and should be addressed before opioid therapy begins. As opioid-induced constipation can be severe and adversely impact quality of life and compliance with therapy, prophylaxis with laxatives is considered to be the best approach. A British Pain Society survey conducted in March 2009 showed that nearly half of GPs (44%) surveyed believe that the negative impact of such side effects is the key factor in patient non-compliance with prescribed opioid treatments.
Concurrent management on initiation of opioids frequently includes recommending certain lifestyle or dietary adjustments (as listed above) and initiating a scheduled regimen of laxatives. Laxative and cathartic therapy may be needed throughout opioid therapy and beyond. Effective management requires a composite of strategies, including behavioral and lifestyle changes (diet, activity, and fluid intake, as appropriate).
However medications used to manage opioid-induced constipation, such as laxatives, do not address the underlying opioid receptor-mediated cause of constipation and are often ineffective4.
Newer targeted treatments for opioid induced constipation
Methylnaltrexone (available as Relistor(R)) helps restore bowel function in patients who have advanced illness and receive opioids for pain relief. Methylnaltrexone is delivered via subcutaneous injection and specifically targets opioid-induced constipation. When given alongside opioid therapy, it is designed to displace the opioid from binding to peripheral receptors in the gut, decreasing the opioid's constipating effects and inducing laxation.
Methylnaltrexone is a peripherally acting mu-opioid receptor antagonist that decreases the constipating effects of opioid pain medications in the gastrointestinal tract without diminishing their ability to relieve pain.
Methylnaltrexone blocks peripheral opioid receptors in the gut and unlike other opioid antagonists has restricted ability to cross the blood-brain barrier. As a result, it antagonizes only the peripherally located opioid receptors in the GI tract, so it's action reverses opioid-induced constipation without precipitating withdrawal symptoms or affecting or reversing the central analgesic effects of opioids5.
Another new medication for severe pain (long-term pain that can be experienced as a result of conditions such as back pain, arthritis and osteoarthritis)6, are tablets combining prolonged release oxycodone, an opioid which treats pain, and prolonged release naloxone, a compound which counteracts the potential negative effects of the opioid on the GI function (available as TarginactTM). This novel combination has been proven to provide equivalent pain relief to oxycodone alone, whilst significantly improving bowel function7. Naloxone is an opioid receptor antagonist that, when taken orally, has negligible systemic bioavailability8 providing a full inhibitory effect on local opioid receptors in the gut - counteracting opioid-induced constipation - without impacting on the centrally acting analgesic efficacy of oxycodone.
* Image borrowed from Wyeth library
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2 comments:
Because of multiple car accidents I have to take 120 – 180mg of morphine (M-Eslon ) daily. OIC (opiate induced constipation) has been a real problem but I recently found a solution that works for me. Costco sells edamame in boxes of 12 ½ pound packages if I eat half a package a day in gets rid of my OIC.
Is this the Japanese food that look like string beans...I love them and ate some last night and actually had a movement! That would be unbelieveable.
Can you confirm its the food you get in Japanese restrs?
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