Constipation Caused by Opioids, New and Old Treatments
Constipation is one of the most common and life-altering side effects of opioids used to manage chronic pain. Although there are a variety of treatment choices, anyone who suffers from opioid-induced constipation may soon have a new option in the form of naloxegol.
Constipation and opioid use
Morphine-based medications (e.g., Vicodin, Percocet, OxyContin) designed to treat chronic severe pain ranging from back pain to cancer and joint pain can be effective for the designed purpose. However, the constipation (as well as the nausea and vomiting) associated with their use can cause some patients to stop treatment or need additional drugs to combat the adverse reactions.
Naloxegol is a new drug that is awaiting approval in both the United States and Europe. Clinical trials have shown that the drug, taken orally once daily, can relieve constipation associated with opioid use without having a negative impact on the ability of the morphine-based drugs to do their job.
Naloxegol is an investigational drug that is known as a peripherally-acting mu-opioid receptor antagonist. The drug works by blocking the attachment of opioids to opioid receptors in the gastrointestinal tract but without affecting the opioid receptors in the brain, thus relieving pain while managing intestinal issues.
A new report in the New England Journal of Medicine spelled out the positive news. Among 1,400 patients who participated in two phase 3 studies conducted by KU Leuven and international experts, bowel function returned to normal and symptoms such as stomach discomfort and pain improved after use of naloxegol. In addition, none of the patients experienced any decline in the pain-relieving abilities of the opioids.
In November 2013, the pharmaceutical company AstraZeneca announced that the Food and Drug Administration (FDA) had accepted the company’s New Drug Application for naloxegol. The application was filed because the company had secured good results from four clinical trials to identify the safety and efficacy of the drug for treatment of opioid-induced constipation. Of these, two involved 1,352 patients who received either 12.5 mg or 25 mg of naloxegol or placebo for 12 weeks, while a third trial (534 patients) lasted one year and was concerned with long-term safety.
Other treatments for opioid-induced constipation
Both lifestyle changes and medical interventions can help in the treatment of constipation associated with opioid use. For example:
- Include more fiber in your diet (e.g., whole grains, beans and legumes, fruits and vegetables)
- Increase the amount of fluids (especially water) you drink
- Increase your physical activity, which in turn improves peristalsis (muscle contractions in the gastrointestinal tract)
- Osmotic laxatives, which increase the amount of water in your gut and soften stools
- Carthartic laxatives, which speed up defecation. You can choose from stimulant cathartics (which help the gut move the contents along), bulk cathartics, which soften stools and increase bulk, or lubricant cathartics, which lubricate and soften stools
- Prokinetic drugs or prostaglandins, which have an impact on how the intestinal tract absorbs water and electrolytes. These drugs can increase the weight of stools and the speed with which they move through the intestinal tract
- Enemas, manual evacuation, glycerine suppositories, and rectal irrigation with saline solution also can be used
- Methylnatrexone (Relistor) is administered subcutaneously and is designed to reduce the constipating effects of opioids while stimulating laxation but not reducing the pain-relieving effects of the opioids. It also is a peripherally-acting mu-opioid receptor antagonist.
Approximately 50 percent or more of individuals who take opioids for treatment of severe chronic pain experience constipation. Introduction of a new oral medication for treatment of constipation associated with opioid use could provide much-welcome relief for many opioid users.
Also read about how to treat constipation naturally
Chey WD et al. Naloxegol for opioid-induced constipation in patients with noncancer pain. New England Journal of Medicine 2014; 370:2387-96