There are times when an opioid medication is appropriate and useful. After a serious injury for example, the body convulses with pain, and without treatment the patient would have to white knuckle it for weeks with strained facial expression, anxiety, and difficulty relating to loved ones. Opioids are also widely used for the treatment of chronic pain in patients with cancer as well as other serious chronic illnesses such as neurologic, spinal and orthopedic pathology. Numerous side effects accompany opioid therapy, the most common of which are neurological and gastrointestinal. Opioid-induced constipation (OIC) is one of the most significant side effects of opiate medications. These medicines slow gastrointestinal function. In the case of long term opioid treatment, patients can lose muscle tone in the colon, with a significant loss of bowel motility. This means that along with slowed absorption of nutrients, the colon loses its ability to push waste from the body. With a prevalence of approximately 60-90%, OIC impacts a patient’s quality of life and adds additional healthcare costs.
The pathogenesis of OIC is multifactorial:
- Genetic differences, age, comorbidity, or interactions with other drugs contribute to a patient’s variability in sensitivity to OIC.
- Opioids bind to receptors in the gastrointestinal tract and central nervous system to reduce gastrointestinal motility or peristalsis.
- Longer colonic transit time, which causes excessive water and electrolyte reabsorption from feces, coupled with decreased biliary and pancreatic secretion further hardens the stool, making its elimination difficult and prolonged.
- Concurrent use of other constipating drugs such as antidepressants, dehydration, immobility or sedentary lifestyle, and metabolic abnormalities may also contribute.
Patients using opioids over a period of weeks or months can experience a serious buildup of waste in the colon and failure to excrete it, potentially resulting in nausea, vomiting, bloating, and in some cases, gastrointestinal pain so severe it requires a trip to the emergency room. ER doctors will prescribe a laxative or an enema at this point, as impacted waste can be life threatening. Chronic constipation has its own risks. Straining in the rest room can result in swollen rectal veins (hemorrhoids), torn skin in the anus (a fissure), rectal prolapse, and even dangerous cardiac symptoms, as serious straining can lead to heart arrhythmia and elevated blood pressure.
Prevention is the preferred strategy. Patients should expect constipation, and be proactive. Those with predisposing factors (advanced age, immobility, poor diet, intra-abdominal pathology, neuropathy, metabolic abnormalities, and concurrent use of other constipating drugs) may need prophylactic laxative therapy during opioid therapy. Ideally however, patients should not find themselves dependent on medicines just to manage basic bodily functions. The healthiest way to fight OIC is with a commitment to nutritious, high fiber plant foods. Cooked squash, spinach, carrots and peas are highly effective, and have numerous health benefits in addition to inducing peristalsis. In the fruit aisle, also excellent are ripe, brightly colored organic pears, plums, and any seed containing berries, especially raspberries. These high fiber plant foods are rich in vitamin C, rich in minerals and other nutrients, and will stimulate restored bodily function.
There are additional approaches to consider when patients with OIC does not respond to conventional preventive and first-line laxative therapies. Some of these treatments, including opioid antagonists and lubiprostone (a type-2 chloride channel activator that induces secretion of fluid in the intestine) are FDA-approved therapies for refractory OIC.