Opioid-Related Bowel Obstruction: Origins, Symptoms, and Solutions
In the management of chronic pain, opioids are often prescribed to alleviate discomfort caused by various conditions such as back pain, joint pain, degenerative joint disease, fibromyalgia, and headaches. However, one of the side effects that patients may experience is constipation, a common issue that can significantly impact quality of life.
Opioids cause constipation primarily by binding to μ-opioid receptors in the gastrointestinal (GI) tract. This binding leads to several effects that disrupt normal bowel function. Opioids inhibit the coordinated contractions of the intestines, slowing down the transit of stool through the bowel. They also decrease the secretion of fluids into the gut, resulting in drier and harder stools. Furthermore, opioids cause tighter contraction of the anal sphincter, making defecation more difficult. Together, these effects cause stool to remain longer in the colon, become harder, and are more difficult to pass, leading to constipation.
Unlike the analgesic effects of opioids, the GI side effects such as constipation do not develop tolerance over time, so constipation usually persists with continued opioid use. The risk and severity of constipation also depend on the dose and type of opioid; morphine, oxycodone, and fentanyl are particularly linked to higher rates of constipation compared to less potent opioids like tramadol or codeine.
To manage opioid-induced constipation, medications known as peripherally acting μ-opioid receptor antagonists (PAMORAs) can selectively block opioid effects in the gut without affecting pain relief in the brain. Examples of PAMORAs include methylnaltrexone, naloxegol, and naldemedine. Other treatments include chloride channel activators like lubiprostone, stimulant laxatives, and stool softeners.
It's important to note that the overprescription of opioids has been a cause for concern, with the Department of Health and Human Services and various organizations expressing their worries about the issue. In palliative cancer care, opioid medications are often prescribed, especially when the disease progresses to later stages.
Adverse side effects of opioids include drowsiness, nausea, slower breathing, general depression of the respiratory system, physical dependence, overdose, misuse, and potential opioid use disorder. To counteract these effects, prostaglandins or prokinetic medications can be used. These medications increase the bulk and movement of stools by changing how the intestines take in water and electrolytes.
Approximately 22% of United States adults experience chronic pain, with about 7% reporting moderate to severe pain. With the understanding of the mechanisms behind opioid-induced constipation and the availability of effective management strategies, healthcare providers can work with patients to find solutions that help alleviate this common side effect and improve overall quality of life.
In the context of managing chronic pain, opioids may alleviate discomfort, but they can also lead to digestive issues, specifically constipation, due to their interaction with the gastrointestinal (GI) tract. This side effect is persistent and may not develop tolerance over time, and it can significantly impact health-and-wellness. To manage opioid-induced constipation, various therapies-and-treatments, like peripherally acting μ-opioid receptor antagonists (PAMORAs) and chloride channel activators, are available. In the broader medical-conditions landscape, the overprescription of opioids is a cause for concern, particularly in the context of chronic diseases like cancer, where opioids are often prescribed in palliative care.
