Opioid-related constipation, also called OIC for opioid-induced constipation, is a very common side effect of opioid drug therapy. Upwards of 90 percent of all patients will experience OIC. Remedies include dietary changes, stool softeners, increased exercise, and special medications specifically designed to treat and prevent OIC. If your spouse has this condition, this article will help to educate you about OIC, and it will also help to answer this question: How can I help my spouse deal with opioid-related constipation?
To understand why OIC occurs, you must first understand some basic information about how opioids work in the body. Opioids relieve pain by binding to special opioid receptors in the brain. This binding changes the way your spouse perceives pain, relieving the pain and often allowing normal activities and an increased quality of life. With all of the recent media hype about the opioid crisis, sometimes even medical professionals forget that some people need these medications for legitimate medical reasons. No one, not even a doctor and especially not a pharmacist, should ever judge your spouse for needing to take opioids for pain relief.
Why do Opioids Cause Constipation?
When opioids bind to receptors in the brain, they also do the same thing to opioid receptors elsewhere in the body, such as those located in the stomach and intestines. The stomach processes food and empties into the intestine on a regular basis, but the action of opioids on its receptors can slow this process. The same thing can happen with the opioid receptors located in the gut. The binding of opioids to these gut receptors can slow peristalsis, which is the normal movement of food through the intestinal tract. The urge to defecate is also blunted. When food stops moving normally through the intestines, stasis occurs. This means that the intestinal contents either don’t move at all or move way to slowly, setting the stage for constipation.
Some people think laxatives are a good remedy for OIC, but this isn’t true. Stimulant laxatives are okay for occasional constipation not caused by opioids, but for OIC, they’re of limited value because they’re not treating the cause of the problem. Stimulant laxatives can be harsh, create painful intestinal cramps and cause a type of rebound dependence of their own. People who take these preparations on a regular basis can become dependent on them because the gut no longer works as it should. When it comes to OIC, there’s a much better treatment.
Although some people do have some success with stool softeners like docusate sodium and osmotics like Miralax, OIC is typically stubborn and resistant to standard constipation treatments like these. This is because these preparations are also not fixing the problem caused by activated gut opioid receptors. However, prescription medications like methylnaltrexone can relieve OIC in as little as six to 12 hours.
How Does Methylnaltrexone Work?
To understand how this drug may help your spouse’s OIC, you must again go back to how opioids work in the brain. We have seen that opioids attach to special receptors in the brain and that they do the same thing to opioid receptors in the stomach and gut as well. These kinds of opioids are called agonists. Methylnaltrexone works to relieve OIC because it’s an antagonist, which is the opposite of an agonist. It relieves constipation by interfering with the action of the opioid agonist on the gut receptor sites. When the opioid agonist is removed from the opioid gut receptor sites, normal bowel function is restored, often within just a few hours.
Methylnaltrexone works only in the gut. If it didn’t, it would also interfere with opioid binding in the brain as well, reversing the pain relief effect. It works only in the gut because it can’t get across the brain’s protective BBB or blood-brain barrier. For complicated molecular reasons, opioid agonists can easily cross the BBB, but methylnaltrexone cannot. Its actions are limited to the stomach and intestines.
It’s still important for your spouse to drink plenty of water, increase fiber intake and exercise regularly. About 30 minutes of brisk walking at least three times a week is good. You can also consider a prebiotic supplement and adding plain yogurt to the diet. All these things will work with the methylnaltrexone or other medication for OIC that may be prescribed for them. Not all OIC medications work the same way. Some, such as lubiprostone, activate intestinal mechanisms that increase fluid content in the bowel. Others, such as naloxegol and naldemedine, work like methylnaltrexone does.
If you’d like more information about the treatment of OIC, we can help. Just call us anytime at 833-846-5669 and our group of drug counselors will be happy to help clear up any questions you have about OIC or where you can get medication to treat it. We’re here to help.