Opioid induced constipation (OIC) occurs in about 40% of patients receiving opioids for non-cancer pain. Opioids such as hydrocodone, oxycodone, and morphine are narcotic medications used to treat moderate to severe pain. They provide analgesic effect when they bind to mu, delta, and kappa receptors that are found throughout the body, including in the brain and spinal cord. However, many mu receptors are found in the gastrointestinal tract. When these receptors are activated bowel movement is decreased. This increased transit time through the bowel can result in excessive water and electrolyte reabsorption and patients can experience constipation. Prolonged constipation can lead to blockage and more seriously, intestinal rupture.
There are many medications used for prevention and treatment of opioid-induced constipation. There are over the counter medications (OTC) for less serious cases to prescription medications for more severe cases of constipation due to opioids.
Other potential causes for constipation should be identified and corrected before starting a laxative when opioid treatment is initiated. Factors that contribute to constipation include age, sedentary lifestyle of immobility, low dietary fiber, loss of ability to stimulate bowels, high calcium levels, and other drugs that cause constipation. If the patient is able to correct other risk factors for constipation medication will be unnecessary. However, if the cause is not modifiable, prophylaxis (prevention) is recommended.
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