CONDITIONS

Opioid-Induced Constipation

What Is Opioid-Induced Constipation

In the United States alone, more than 240 million opioid prescriptions are dispensed every year and roughly 3% of all Americans are prescribed an opioid regimen for chronic non-cancer pain relief.

A common adverse side effect of opioid medications is opioid-induced constipation, or OIC, which occurs in 40% to 90% of patients taking opioids.  If you are taking opioids, your doctor should evaluate you for any signs of OIC.

To more deeply understand OIC, we must first take a look at what opioids are, and how they can cause constipation.  Constipation occurs when bowel movements become less frequent and more difficult to pass.

Opioid (or narcotic) pain medications— best known colloquially as “painkillers”, are a class of drugs commonly prescribed for their pain-reducing—or analgesic—qualities, and include substances like oxycodone, hydrocodone, codeine, and morphine. You might recognize these drugs by their brand names: Oxycontin, Vicodin, Percocet, among others.  These medications have been used as a means of providing pain relief for many years. They are also are used for medical, as well as nonmedical, purposes, including:

Pain relief—With respect to pain relief, opioids are used to treat:

  • Acute pain post-surgery—one of the most common clinical uses for opioids is to treat post-surgical acute pain
  • Cancer pain—often used to relieve pain caused by cancer, especially in advanced or end stages. This is also referred to as palliative care, since these medications may be the only way to relieve terminal pain in patients at the end of their lives. About 70% of patients with advanced cancer commonly complain of pain.
  • Injury or trauma—pain associated with injury or trauma is another common clinical use for opioids
  •  Pain arising from chronic disease—pain associated with severe, chronic, debilitating diseases, like complex regional pain syndrome may be treated with opioids.

Anesthesia—Opioids are typically used as anesthetic regimens that aid in surgical procedures.

Cough suppression—Opioids (such as codeine), combined with other agents, may suppress cough, and some are used for this clinical purpose, especially if a dry and non-productive cough presents.

Diarrhea suppression—Opioids typically cause constipation, and as such, they are sometimes utilized in the treatment of diarrhea

Addiction treatment —Certain types of opioids, methadone in particular, are used to help opiate or narcotic addicts wean off stronger opioids like heroin to help prevent severe withdrawal symptoms.

Severe Anxiety—In very rare cases, opioids may be used to treat severe anxiety.

The vast majority of patients receiving long-term opioid pain medication are in advanced stages of their disease. Despite their analgesic benefits, opioids can cause a number of side effects, the most commonly occurring of which is opioid-induced constipation, or OIC. Patients develop a tolerance for many of the other side effects of opioids, such as respiratory depression. However, patients generally do not develop a tolerance to OIC.  Altogether, studies indicate that as many as 81% of patients who are prescribed opioids experience OIC.

What Causes Opioid-Induced Constipation

Opioids affect a specific set of receptors in the central nervous system, or CNS, and they may also function in the gastrointestinal, or GI, tract.  More specifically, opioids bind to mu receptors in both the CNS and GI tract. In the CNS, this results in pain relief. In the GI tract, however, this tends to inhibit the normal functioning of the GI system, particularly the intestines and colon, resulting in severe constipation.

Opioids are effective pain relievers, but often have the side effect of constipation, which can be severe, especially with long-term use. Opioid pain medications affect the GI system in a number of ways, including:

  • Increasing the amount of time it takes a bowel movement to move through the system
  • Paralyzing the stomach, which makes food remain in digestive tract for longer period of time
  • Reducing digestive secretions
  • Slowing the ability of food to moving through the intestines by causing sluggish peristaltic movement in the intestines (peristalsis is movement that is key to moving food through the system)
  • Decreasing the urge to defecate

Risk Factors For Opioid-Induced Constipation

Taking opioid-based substances—legal or illicit—puts you at risk for OIC. Along with opioid use, you may be at higher risk for OIC based on the following factors:

  • Sex—Female patients are more likely to develop OIC than males
  • Age—The older a patient is, the more likely they are to develop OIC. Patients older than 70, in particular, are more likely to develop OIC
  • Other medications—A number of different medications can cause constipation and may exacerbate problems with OIC when used concurrently. Some examples include:
    • Anticholinergic medications
    • Medications that contain magnesium or calcium
    • Certain antihistamines
    • Certain antidepressants
    • Diuretics

Other factors that may impact OIC include:

  • Dose—the higher the dose, the more likely OIC is to occur
  • Type of opioid medication
  • Route of administration—sometimes changing the route of administration can decrease OIC symptoms
  • Different types of opioids affect people differently—sometimes alternating between different opioid medications can lessen effect of OIC

Diagnosing Opioid-Induced Constipation

Your doctor will gather your medical history to check for standard problems associated with constipation, like:

  • Too little fiber and fluid intake
  • Too little exercise
  • Underlying medical problems
  • Current medications

Be prepared for a physical assessment that may necessitate oral, abdominal, and anorectal examination. Opioid-induced constipation is a clinical condition characterized by slowed gastrointestinal movement, and occurs in 90% of all patients that take opioids for advanced cancer pain. This condition is characterized by a number of symptoms, which include:

  • Constipation—defined as fewer than three bowel movements a week (or a marked shift from a person’s normal pattern
  • Dry, hard stools
  • Straining when making bowel movements
  • Incomplete passage of stool

The symptoms of OIC can be very similar to those of opioid bowel disorder (OBD), which can pose a challenge when making a diagnostic assessment.

Symptoms of Opioid-Induced Constipation

Common physical symptoms of OIC include:

  • Hard, dry bowel movements
  • Difficulty making a bowel movement, which can include straining, forcing, and/or pain when defecating
  • A constant feeling of needing to use toilet
  • Bloating
  • Abdominal tenderness

Other symptoms of OIC include:

  • Feeling and/or being sick
  • Being tired and/or lethargic
  • Suppression of appetite
  • Feeling depressed

Prognosis

Cessation of opioid use may quickly alleviate OIC symptoms; however; this is not a recommended approach for treatment. Recent advances in the understanding of the etiology of OIC have brought forth the development of targeted pharmacologic regimens that prove effective at both alleviating OIC symptoms while also maintaining the analgesic or pain relieving, effects of the opioid medications. Recently conducted studies indicate that as many as 81% of patients who are prescribed opioids experience OIC.

Living With Opioid-Induced Constipation

Opioid medications are extremely effective for the treatment and management of pain, however their frequent use results in opioid-induced constipation, or OIC.  Treatment options for OIC range from simple diet changes to stool softeners and laxatives to the use of specialized medication that specifically treats constipation that occurs due to long-term use of opiate medication.

Talk to your doctor about whether the following lifestyle changes might help with your OIC. Lifestyle changes that may prove beneficial include increasing:

  • Dietary fiber—by consuming more whole grains, fruits and vegetables
  • Fluid intake—particularly water
  • Exercise of physical activity
  • Time and privacy for going to the toilet

Changes in lifestyle, however, may not be possible for many patients, and may ultimately prove 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.

Screening

Constipation is the most frequently cited side effect for long-term opioid therapy. Screening for OIC should begin with a thorough personal history of bowel habits prior to using opioids.  A rectal examination may prove useful in screening for OIC, but is not always necessary. Opioid-induced constipation should be monitored often, daily in some cases. A patient should work with their doctor to develop protocols to address specific lengths of time in which he or she has been without a bowel movement. Impaction must be ruled out before starting treatment for constipation.

Prevention

It’s important to remember that only those who take opioid medications are at risk for OIC. In other words, this condition is not necessarily preventable in the way that other conditions may be.

Common Treatment

OIC symptoms usually require medical treatment with a therapeutic regimen that accompanies the opioid painkillers that are causing the constipation. Withholding opioid treatment is ill advised because it results in a decrease in the patient’s quality of life.

For the treatment of OIC, doctors may recommend:

  • Osmotic laxatives – which increase the amount of water in the gut, increasing bulk and softening stools.
  • Emollient or lubricant cathartics – that soften and lubricate stools.
  • Bulk cathartics – which increase bulk and soften stools.
  • Stimulant cathartics – which directly counteract the effect of the opioid medications by increasing intestinal motility, helping the gut to push the stools along.
  • Prostaglandins or prokinetic drugs – which change the way the intestines absorb water and electrolytes, and they increase the weight and frequency of stools while reducing transit time.
  • Other medicines that block the effects of opioids on the bowel to alleviate OIC symptoms
  • Rectal intervention, as deemed appropriate by the physicians

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 all general practitioners (GP) (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 ineffective. Therefore, pharmacotherapeutic intervention may be necessary.

Methylnaltrexone (available as Relistor) helps restore bowel function in patients who have advanced illness and receive opioids for pain relief. Methylnaltrexone is delivered via subcutaneous injection and 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 (PAMORA) that decreases the constipating effects of opioids in the GI tract without affecting pain relief.

Additionally, lubiprostone (available as Amitiza) is a chloride channel activator that is utilized in the treatment of OIC in adults with chronic, non-cancer pain.

Complementary and Alternative Treatment

There are a number of  complementary and alternative therapies that can help with opioid-induced constipation, among them:

  • Acupuncture is a traditional form of Chinese medicine that uses hair-thin needles to target specific points along bodily energy channels. Acupuncture can help reduce stress levels, thereby improving gastrointestinal motility.
  • Dietary and herbal supplements, such as senna, which is a very effective herbal laxative
  • Lifestyle modifications, such as:
    • Increasing fluid and fiber intake
    • Augmenting physical activity, as needed
    • Instituting a “toileting routine”
    • Lubricating the rectal area with mineral oil

Care Guide

It’s important to remember that your OIC is caused by a medication that, if prescribed and taken properly, will exponentially increase your overall quality-of-life by decreasing your pain and getting you back to a more functional place. And OIC should not cause you embarrassment. Speak with your doctor right away if you should experience OIC symptoms.

When To Contact A Doctor

Speak with your physician if you are experiencing these symptoms while taking opioid medication:

Fewer than 3 bowel movements per week, with at least 25% of those bowel movements associated with one (or more) of the following conditions:

  • Moderate to very severe straining
  • Hard to very hard stools
  • Feeling like your bowel is never completely empty

Questions For Your Doctor

If you are experiencing discomfort and you think you may have opioid-induced constipation, call the doctor that prescribed your medication. You might also want to call a gastroenterologist.

Questions For A Doctor

Due to the nature of this condition, you may likely be reluctant to speak with your doctor about your OIC; however, it is imperative that you do. Some questions that may help initiate the conversation include:

  • How long will the constipation last?
  • What lifestyle modifications may help alleviate my OIC?
  • Should I increase my daily fluid intake?
  • Will coffee help?
  • Should I eat extra fiber?
  • Are there exercises I can do that will help my OIC?
  • What about laxatives and stool softeners—do you recommend these for my OIC?
  • Should I take less of my opioid medication to alleviate my OIC symptoms?

Resources

For more information on opioid-induced constipation, see:

Medical News Today

Practical Pain Management

ACP Online