A review of the pathways associated with opioids may help to explain the causes of OIC.
Opioid medications bind to opioid-specific receptors in the central nervous system that in turn trigger cascades of events that eventually lead to the desired analgesic effect
(Gutstein & Akil, 2006). The muopioid receptors are also located in the entericnervous
system. The effects of opioids on the gastrointestinal tract are mediated thought
the muopiod receptors in the bowel (Gutstein & Akil,2006). When a patient takes opioids, the drug molecules will not only bind to the opioid receptors in the central nervous system.
but also to the opioid receptors in the enteric nervous system (Gutstein & Akil,2006).
This event may cause disturbance to the normal physiology of the gastrointestinal tract(Gutstein & Akil,2006).
Physiologically, opioids prompt multiple actions in the gastrointestinal tract that hinder normal gastroinal transit. In both small and large intestines, non-propulsive luminal contractions are enhanced while propulsive luminal contractions are reduced, resulting in
reduced forward peristalsis in those organs. Secretion in the small intestine is decreased, and more water is absorbed, so stool becomes dry and hard to pass. The tone of ileocecal and anal sphincters is enhanced, and defecation response is affected. Collectively, these
effects bring about constipation that is a direct result of opioid therapy. Overall, the effects
of opioids on intestinal motility are not as simple as an increase or decrease in luminal
contraction. The combination of increased non-propulsive contraction and decreased propulsive contraction disrupts orderly intestinal motility OIC can cause or result in abdominal pain, nausea and vomiting, or fecal impaction
One correcting strategy would be removing the cause of constipation. However, because withdrawal of opioids is not an option for many advanced illness patients receiving palliative care, one would then seek remedies that address the physiologic effects of opioids on the intestinal tract.
lubricating the intestinal lumen, or softening the stool.
The task of home health nurses in monitoring symptom management is very important. The remainder of this article discusses for OIC in advanced illness patients receiving palliative care, when response to laxative therapy has been insufficient.
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