Constipation is pretty common in older adults, ranging from 24 to 50 percent. Up to 20 percent of community-dwelling older adults and 74 percent of nursing home residents use laxatives on a daily basis. Age, immobility, comorbid conditions, polypharmacy, eating less and inadequate hydration are all risk factors for constipation.
Chronic constipation is defined as constipation that lasts ≥ 3 months. Management starts with modifying any secondary contributors, including systemic conditions and medications.
Disease states that can increase risk of constipation:
- Spinal cord injury
- MS
- Parkinson’s
- Endocrine: diabetes, hypothyroidism, hypercalcemia, hypokalemia
- Myopathies: systemic sclerosis, myotonic dystrophy
- Colorectal cancer, colonic stricture
- IBS *Treatment not discussed here.
- Anorexia
- Celiac Disease
Medications that can increase risk of constipation (*list not all-inclusive):
- Opioids *Opioid-induced constipation treatment not covered in this document.
- Blood pressure medications:
- Calcium-Channel Blockers (CCBs) : Amlodipine, Nifedipine, Diltiazem, Verapamil
- Clonidine
- Iron (Ferrous Sulfate, Ferrous Gluconate)
- Antacids (Calcium Carbonate (Tums), Maalox, Mylanta)
- Sucralfate (Carafate), Ondansetron (Zofran)
- Anticholinergics:
- Urinary incontinence medications: Oxybutynin (Ditropan), Tolterodine (Detrol), etc.
- 1st generation antihistamines: Diphenhydramine (Benadryl), Hydroxyzine (Atarax), Chlorpheniramine
- Tricyclic antidepressants: Amitriptyline (Elavil), Doxepin (Sinequan), Nortriptyline (Pamelor)
- Antipsychotics (1st generation more so): Haloperidol (Haldol), Prochlorperazine (Compazine), Olanzapine (Zyprexa), etc.
- In some cases, management of the underlying condition and/or removal of the medication can lead to resolution of the constipation. However, this is not always feasible.
Categories of medications used to treat chronic constipation:
Bulk-forming laxatives
These work by increasing the weight and water-absorbent properties of stool. By retaining
water in stool, the fiber increases stool bulk, which causes colonic distention and promotes stool
propulsion.
- Examples: Psyllium (Metamucil), Methylcellulose (Citrucel), Polycarbophil (Fibercon), Wheat dextrin (Benefiber).
- Adverse effects: fluid overload, gas, bloating, impaction above strictures.
- Caveats: these should be avoided if suspicion for slow transit constipation. Administer with 6-12 ounces of fluid. DO NOT give within 2 hours of other medications.
Osmotic laxatives
These work by increasing endogenous prostaglandin from intestinal mucosa, leading to increased colonic fluid and electrolyte secretion. They also increase intestinal motor activity.
- Examples: polyethylene glycol (Miralax), Lactulose, Sorbitol, Glycerin, Magnesium Sulfate, Magnesium citrate, Magnesium hydroxide (MOM).
- Adverse effects: nausea, bloating, cramping, flatulence.
- The Magnesium-based laxatives can all cause watery stools and urgency and should be used cautiously in renal impairment due to risk of Magnesium accumulation and toxicity.
- Caveats: polyethylene glycol (Miralax) is typically preferred here as it is pretty well tolerated, effective, and inexpensive.
Stimulant laxatives
These work by increasing endogenous prostaglandin from intestinal mucosa, leading to
increased colonic fluid and electrolyte secretion. They also increase intestinal motor activity.
- Examples: Bisacodyl (Dulcolax), Senna
- Adverse effects: abdominal pain, cramping, gastric irritation. The rectal formulation can cause rectal irritation (Bisacodyl)..
Secretagogues
These work by activating GC-C in the intestinal epithelium. This activation results in an increase in intracellular concentrations of cyclic guanosine monophosphate (cGMP) which stimulates secretion of chloride and bicarbonate into the intestinal lumen. This action results in increased intestinal fluid and accelerated gastrointestinal (GI) transit.
- Linaclotide (Linzess), Plecanatide (Trulance), Lubiprostone (Amitiza)
- Adverse effects: diarrhea, bloating, nausea.
- Caveats:
- Linzess and Trulance are preferred as they have similar efficacy and are associated with less adverse effects.
- Linzess: should be taken on an empty stomach. If taken with a high fat meal, the risk of diarrhea and other adverse effects are increased.
- Amitiza: should be given with food and water to minimize risk of adverse effects. Can take up to a month to work.
- These are all contraindicated in individuals with a history of mechanical intestinal obstruction.
Stool softeners
These lower the surface tension at the oil-water interface of the feces, allowing water and lipids to penetrate the stool. This helps to hydrate and soften the fecal material, facilitating natural defecation.
- Docusate (Colace)
- Adverse effects: well tolerated, however much less effective than other agents.
- Caveats: It has been shown that Docusate is ineffective at relieving the multiple symptoms of chronic constipation with long term use. In fact, experience shows us no discernable changes when long term therapy has been discontinued.3
Treatment Guidelines for Chronic Constipation
- Daily bowel movements are not necessary for health. The goal of treatment is to improve bowel-related symptoms that are bothersome to the patient.
Initial Management
- Ensure adequate fiber intake: 20-35 grams daily. Dietary fiber is preferred, but supplemental fiber can be used if needs cannot be met through the diet. Start with smaller amounts and slowly increase to minimize risk of adverse effects.
- Hydration: at least 1.5 L of water daily.
- Physical activity: 140 minutes/week of aerobic exercise.
- Attempt bowel movements after waking and/or within 2 hours after meals as this is when colonic motility is at its highest.
- Defecation posture modification (squat assist device).
Persistent Symptoms
- Add daily osmotic laxative while continuing non-pharmacological interventions.
- If symptoms still occur, add a stimulant laxative PRN.
If symptoms still persist, reassess for alarm symptoms and rule out defecatory dysfunction. If alarm symptoms are ruled out and there is a low suspicion for defecatory dysfunction, consider a secretagogue, while ensuring current therapy is optimized.
- Alarm symptoms: Heme-positive stool or hematochezia, iron deficiency anemia, new onset of unexplained constipation, unexplained weight loss of ≥ 10 pounds, rectal pain, new obstructive symptoms (distention, abdominal pain during stool passage, bloating, family history of colon cancer or inflammatory bowel disease.
References:
- Management of chronic constipation in adults. Uptodate.
- Clinical Pharmacology. Monographs. https://www.clinicalkey.com/pharmacology/monograph
- American Gastroenterological Association Institute Guideline on the Medical Management of Opioid-Induced Constipation. AU Crockett SD, Greer KB, Heidelbaugh JJ, Falck-Ytter Y, Hanson BJ, Sultan S, American Gastroenterological Association Institute Clinical Guidelines Committee SO Gastroenterology. 2019;156(1):218. Epub 2018 Oct 16.
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