Overview

Constipation refers to a decrease in the frequency of fecal elimination characterized by straining and the difficult passage of hard, dry stools. It usually results from the abnormally slow movement of feces through the colon with subsequent accumulation in the descending colon. In adults, constipation generally is associated with having less than three bowel movements per week.

Pharmacists should be aware that patients may use the term “constipation” to refer to any of the following: (1) straining to have a stool; (2) the passage of hard, dry stool; (3) the passage of small stools; (4) feelings of incomplete bowel evacuation; or (5) decreased stool frequency. Patients may use laxatives inappropriately to alleviate what they incorrectly consider to be constipation.

Epidemiology

• Constipation occurs throughout the age continuum in both men and women. The prevalence in the general population ranges from 2% to 28%.
  
  
  
  • Older adults (>65 years of age) are five times more likely than younger adults to develop constipation.
    
  • Women are more than three times as likely as men to experience constipation.
  
  
• Constipation is a frequent complaint in late pregnancy and after childbirth.

Etiology

• Causes of constipation include various medical conditions, psychological disorders (e.g., depression and eating disorders), and physiologic conditions (e.g., menopause and dehydration), as well as lifestyle factors (e.g., sedentary lifestyle).
  
• Avoiding the urge to empty the bowel can eventually lead to constipation. When this stimulus is ignored or suppressed, rectal muscles can lose tonicity and become less effective in eliminating stool.
  
• A diet that is low in calories, carbohydrates (e.g., Atkins diet), or fiber may contribute to diet-related constipation.
  
• Inadequate fluid intake may contribute to the development of constipation in patients who are dehydrated.
  
• A number of medications have constipating adverse effects (see Table 1). Opioid-induced constipation is a common reason for self-care laxative use.

TABLE 1. Selected Drugs That May Induce Constipation

Analgesics

Antacids

Anticholinergic agents

Anticonvulsants

Antihistamines (primarily sedating antihistamines)

Antihypertensive agents (e.g., angiotensin-converting enzyme inhibitors, beta-blockers)

Antimotility agents (e.g., diphenoxylate, loperamide)

Antiparkinson agents (e.g., bromocriptine)

Antipsychotics (e.g., phenothiazines, butyrophenones)

Barium sulfate

Benzodiazepines (especially alprazolam and estazolam)

Calcium channel blockers

Calcium supplements

Cholesterol-lowering agents (e.g., cholestyramine, statins)

Diuretics

Hematinics (especially iron)

Memantine

Monoamine oxidase inhibitors (e.g., phenelzine)

Opiates

Parasympatholytics (e.g., atropine)

Polystyrene sodium sulfonate

Sucralfate

Tricyclic antidepressants

Vinca alkaloids (e.g., vincristine)

Signs and Symptoms

• Patients who complain of “constipation” typically report a decrease in frequency of passing stools or difficulty passing stools.
  
• Other symptoms may include anorexia, dull headache, lassitude, low back pain, abdominal discomfort, bloating, and psychosocial distress.

Complications

• Left untreated, constipation can lead to complications that include hemorrhoids, anal fissures, rectal prolapse, and fecal impaction.

Treatment

• Occasional bouts of temporary constipation are amenable to treatment with self-care measures.
  
• Constipation should be managed initially by adjusting the diet to include foods high in fiber and by increasing fluid intake, accompanied by some form of exercise.
  
• Pharmacologic intervention can be used in conjunction with lifestyle modifications if more immediate relief is desired.

General/Nonpharmacologic Treatment Measures

• Dietary fiber increases stool weight and also tends to normalize bowel movement frequency and gastrointestinal (GI) transit time.
  
  
  
  • The American Dietetic Association recommends an adult daily dietary fiber intake of 14 grams per 1,000 kcal, or 25 grams for adult women and 38 grams for adult men.
    
  • For children >2 years of age, dietary fiber intake should equal or exceed their age plus 5 g/day.
    
  • Dietary fiber encompasses insoluble fiber (e.g., whole grains and wheat bran) and soluble fiber (e.g., oat bran, barley, peas, carrots, citrus fruits, and apples). Patients complaining of constipation should aim to gradually increase their intake of insoluble fiber, which passes through the GI tract largely unchanged.
    
  • Patients should limit intake of foods with little or no fiber, such as cheese, meat, and processed foods.
  
  
• Patients who find it difficult to consume a sufficient amount of high-fiber food may choose to supplement their diet with one of the many commercially available fiber supplements or fiber-supplemented foods.
  
  
  
  • Newer flavor-free, texture-free fibers such as inulin are classified as dietary supplements (versus traditional fibers such as psyllium and methylcellulose, which are classified as bulk-forming laxatives and approved by the Food and Drug Administration (FDA) as nonprescription medications). Many newer fibers have not been studied as laxatives, so they may or may not provide the same laxation benefits as traditional fibers.
  
  
• An increase in the intake of fluids, especially water, is recommended in conjunction with increased fiber intake.
  
  
  
  • In general, 2 liters of fluid per day is recommended for adults.
    
  • Fluid requirements increase for pregnant and lactating women; an additional 300 mL and 750–1000 mL of fluid, respectively, should be added to daily requirements.
  
  
• Promptly heeding the urge to pass stool and allowing sufficient time for toileting are important. Gastrocolic reflexes are greatest first thing in the morning and 30 minutes after a meal; attempting a bowel movement at these times helps to promote defecation consistent with the body’s normal physiologic response.

TABLE 2. Classification of Laxatives

Stay updated, free articles. Join our Telegram channel

Join