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Once secondary causes of constipation have been evaluated and addressed as possible, the management of constipation varies according to type. The treatment and prevention of slow-transit constipation includes patient education about bowel habits, dietary changes, and drug therapies. Management of dyssynergic defecation involves biofeedback, relaxation exercises, and suppository programs. Patients with slow-transit and dyssynergic defecation should receive treatment for the dyssynergia first before other measures are started.
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Nonpharmacologic Therapy
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Nonpharmacologic treatment options or lifestyle modifications involve diet, exercise, and biofeedback (if dyssynergic defecation is diagnosed). Very little clinical trial evidence exists to support dietary and exercise recommendations that are recommended to prevent or treat constipation, especially in older adults.
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Dietary options include increasing fluid and fiber. In one study of 883 people >70 years of age, there was no association between estimated fluid intake and constipation; however, in 21,000 nursing home residents a weak association was found between decreased fluid intake and constipation. Adequate fluid intake may be an important general health recommendation and may also impact treatment of constipation, especially with fiber supplementation. The daily recommended amount of fiber is 20–35 g/day, but most Americans only consume 5–10 g/day. Increasing daily fiber intake through dietary measures is recommended. Information should be given on the fiber contained in common foods. Patients should increase fiber intake slowly—5 g/day at 1-week intervals—until the recommended intake is attained. Patients should be informed that an immediate response is not expected, and that flatus and bloating may occur, but are usually temporary. Increasing fiber intake gradually may help with some of these unwanted side effects.
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Probiotics have also been tested for the treatment of constipation. Lactobacillus and Bifidobacterium are symbiotics flora in the large intestine that may promote colonic mucosal health. Low levels of both have been reported in individuals with chronic constipation. Although properly controlled trials are lacking, some prospective evidence does report efficacy of probiotics (Lactobacillus) improving constipation in nursing home residents. Survival and viability of these probiotic bacteria in a commercial form has not been standardized for these treatments to have high levels of evidence for clinical use.
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Increased physical activity is associated with lower rates of constipation in older adults. Physical inactivity may also be associated with reduced colonic transit time. Exercise should be encouraged in older adults, when appropriate.
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Biofeedback is an effective treatment for dyssynergic defecation, which is characterized by paradoxical contraction or failure to relax the pelvic floor muscles during defecation. Biofeedback can involve both sensory training and muscle contraction/relaxation techniques. In patients with dyssynergic defecation, biofeedback was consistently found to be more effective than continuous use of polyethylene glycol (PEG, MiraLAX), standard therapy (other types of stool softners and laxatives), sham therapy (therapy aimed at overall body relaxation), or the use of diazepam in 4 randomized controlled trials. However, trials are needed to determine the efficacy of biofeedback in older adults.
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Many people will have already tried fluids, fiber, and fitness, but often not in a sustained manner. Most Americans do not consume enough dietary fiber and increasing the intake of fiber and fluids may be enough to help prevent constipation in healthy older adults. Consideration may also involve nutritional expertise, physical therapy (when appropriate), and family/caregivers in making dietary and exercise changes for the treatment of constipation. Preventing and treating constipation with nonpharmacologic and pharmacologic treatments may be needed for older adults in specific situations—that is, in the postoperative period, during hospitalization, or other health care environments when decreased mobility is anticipated—and when using acute or chronic opioid medications.
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Pharmacologic Therapy (Including Nonprescription Preparations)
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The main categories of medications for prevention of constipation (nonprescription preparations) are bulking agents, stool softeners/emollients, and osmotic agents. The main categories for the treatment of chronic constipation are bulking agents, stool softners/emollients, osmotic agents, stimulants, chloride change activators, 5-HT4 receptor agonists, and guanylate cyclase-c receptor agonists. Table 36–3 lists the pharmacologic treatments for constipation based on existing evidence from the American College of Gastroenterology Chronic Constipation Task Force.
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Bulking agents expand with water to increase the bulk of the stool with the result of having softer stool. Patients may need to try different types of fiber to achieve the desired outcome, including minimization of side effects. Some patients may better tolerate soluble and synthetic bulking agents than insoluble agents. Adequate hydration with bulking agents may be necessary for the desired outcome. Patients taking fiber need to increase their fluid intake to 30 mL/kg of body weight daily to avoid worsening of constipation or impaction. Fiber may also inhibit the absorption of other drugs and should be taken 1 hour before or 2 hours after other medications. Bulking agents should also be increased slowly over weekly periods to avoid side effects, similar to increasing dietary fiber consumption. Bulking agents are considered to be first-line agents for constipation. However, many older adults may not be good candidates for using a bulking agent. Some examples of when bulking agents may not be the first-line agent for older adults with constipation include when taking high doses of narcotic medications, difficulty with swallowing or dysphagia (because of the consistency of certain types of fiber when mixed with water), anyone with surgical resection of the majority of the colon, patients who have a suspected rectal mass or possible bowel obstruction, and older adults who do not consume adequate amounts of fluid.
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Stool softeners and emollients—
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Stool softeners and emollients are effective by having a detergent effect on the stool consistency. This class of medications for constipation is well tolerated and does not interfere with other medications. Although no placebo-controlled trials exist for the use of these medications, in a study in 170 patients, psyllium husk was as effective for softening stools and had similar overall efficacy as docusate. Mineral oil is also an emollient and may help lubricate the stool through the colon. Aspiration and lipoid pneumonia are known risks of using mineral oil in older adults. Stool softeners are often used when bulking agents do not work or are not preferred. Because of their mechanism of action as a detergent, stool softeners can also be used in combination with bulking agents. Like bulking agents, stool softeners alone are not good treatments for older adults on narcotic medications who have constipation.
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Osmotic laxatives promote the secretion of water into the intestinal lumen by osmotic activity and the hyperosmolar nature of these medications. PEG has the best evidence of use and is now available over-the-counter as a treatment for occasional constipation. It improves stool frequency and consistency in patients with chronic constipation. Studies suggest that PEG can be dose adjusted or used every other day with efficacy. An open-label study with 117 participants, ≥65 years of age, using PEG over 12 months reported relatively few side effects and no serious adverse events related to the medication. A recent evidence-based review article concluded that PEG may be better for constipation symptoms than lactulose. Common use of PEG or magnesium hydroxide-containing preparations (milk of magnesia) in patients with congestive heart failure or chronic renal disease should be done with extreme caution as they can cause electrolyte imbalances, such as hypokalemia and diarrhea, further worsening fluid–electrolyte balances. Osmotic agents are useful when first-line bulking agents and/or stool softners are not effective.
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Stimulants, such as senna and bisacodyl-containing compounds, increase intestinal motility by increasing peristaltic contractions. Stimulants also decrease water absorption from the lumen. Patients usually report more unfavorable side effects from these medications: abdominal discomfort and cramping. Evidence exists for using bisacodyl given placebo-controlled studies. Evidence also exists for senna, although fewer clinical trials exist comparing senna to placebo than that for bisacodyl. There is no evidence to support that long-term use of stimulant laxatives damages the enteric nervous system. Stimulant laxatives have been associated with melanosis coli. The presence of melanosis coli (which may be seen on colonscopy) is a marker of chronic laxative use and may not indicate any other clinical consequences.
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5-HT4 (serotonin) agonists—
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5-Hydroxytryptamine receptor subtype 4 (5-HT4) receptors are found in the colon and mediate the release of other neurotransmitters that may initiate peristaltic action. These prokinetic agents enhance gastrointestinal motility by increasing intestinal contractions. These drugs are no longer marketed in the United States, and little data exist for use in older adults. Other prokinetic agents, such as metoclopramide and erythromycin, have not been formally evaluated for the treatment of constipation. Because of the side-effect profile in older adults, metoclopramide should not be used for chronic constipation.
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Colonic secretagogues (increases intestinal fluid secretion)
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Chloride channel activators—
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Lubiprostone is a chloride channel activator that improves motility in the intestine by increasing intestinal fluid secretion without altering serum electrolyte concentrations. Retrospective data from 3 pooled clinical trials of lubiprostone in older patients (n = 57) without significant comorbidities showed improvement in stool frequency, stool consistency, and decreased straining compared to patients taking placebo. The side effects of this medication include nausea, diarrhea, headache, abdominal distention, and abdominal pain, and are generally well-tolerated.
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Guanylate cyclase C receptor antagonists—
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Linaclotide is another colonic secretagogue that stimulates intestinal fluid secretion and transit. Two large phase 3 trials have been performed in patients with chronic constipation, and the linaclotide-treated groups had significantly higher rates of 3 or more complete spontaneous bowel movements per week and in increase in 1 or more complete spontaneous bowel movements from baseline during at least 9 of 12 weeks compared with placebo. The most common adverse event was diarrhea, which led to discontinuation of treatment in approximately 4% of patients. The long-term risks and benefits of linaclotide in treating chronic constipation remain unknown.
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Two peripherally acting mu opioid receptor antagonists exist that may have some role in the treatment of opiate-induced constipation and paralytic ileus (alvimopan and methylnaltrexone). Data are lacking currently in older adults. These medications act peripherally and do not cross the blood brain barrier, thus not affecting the analgesic properties of opioids.