Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Chapter 79 Laxatives

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.2 Laxatives Used to ease or stimulate defecation Used to ease or stimulate defecation Soften the stool Soften the stool Increase stool volume Increase stool volume Hasten fecal passage through the intestine Hasten fecal passage through the intestine Facilitate evacuation from the rectum Facilitate evacuation from the rectum Misuse comes from misconceptions of what constitutes normal bowel function Misuse comes from misconceptions of what constitutes normal bowel function

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.3 Laxative Effect vs. Catharsis Laxative effect Laxative effect Production of soft, formed stool over a period of 1 or more days Production of soft, formed stool over a period of 1 or more days Relatively mild Relatively mild Catharsis Catharsis Prompt, fluid evacuation of the bowel Prompt, fluid evacuation of the bowel Fast and intense Fast and intense

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.4 Function of the Colon Absorbs water and electrolytes Absorbs water and electrolytes Absorption of nutrients is minimal Absorption of nutrients is minimal 1500 mL of fluid enters colon each day 1500 mL of fluid enters colon each day 90% of fluid is absorbed 90% of fluid is absorbed Delayed transport through colon causes excessive fluid absorption and hard stool Delayed transport through colon causes excessive fluid absorption and hard stool Frequency of bowel elimination varies widely (2–3 times/day to 2 times/wk) Frequency of bowel elimination varies widely (2–3 times/day to 2 times/wk)

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.5 Dietary Fiber Proper function of bowel is highly dependent on dietary fiber (bran is best source) Proper function of bowel is highly dependent on dietary fiber (bran is best source) Absorbs water: softens feces and increases size Absorbs water: softens feces and increases size Can be digested by colonic bacteria whose growth increases fecal mass Can be digested by colonic bacteria whose growth increases fecal mass Low-fiber diet: frequent cause of constipation Low-fiber diet: frequent cause of constipation

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.6 Constipation One of the most common GI disorders One of the most common GI disorders People seek medical help for constipation in the United States at least 2.5 million times a year People seek medical help for constipation in the United States at least 2.5 million times a year Hundreds of millions of dollars a year spent on laxatives Hundreds of millions of dollars a year spent on laxatives Constipation may be defined as Constipation may be defined as Hard stools, infrequent stools, excessive straining, prolonged effort, sense of incomplete evacuation, unsuccessful defecation Hard stools, infrequent stools, excessive straining, prolonged effort, sense of incomplete evacuation, unsuccessful defecation

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.7 Indications for Laxative Use Obtaining fresh stool sample Obtaining fresh stool sample Before treatment/procedure preparation Before treatment/procedure preparation Expelling dead parasites after treatment Expelling dead parasites after treatment Constipation (multiple causes, including pregnancy and opioid use) Constipation (multiple causes, including pregnancy and opioid use) Preventing fecal impaction in bedridden patients Preventing fecal impaction in bedridden patients Removing poisons Removing poisons

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.8 Contraindications of Laxative Use Individuals experiencing abdominal pain, nausea, cramps, or other symptoms of appendicitis, regional enteritis, diverticulitis, and ulcerative colitis Individuals experiencing abdominal pain, nausea, cramps, or other symptoms of appendicitis, regional enteritis, diverticulitis, and ulcerative colitis Acute surgical abdomen Acute surgical abdomen Fecal impaction or bowel obstruction Fecal impaction or bowel obstruction Habitual use Habitual use Use with caution in pregnancy and lactation Use with caution in pregnancy and lactation

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.9 Classification of Laxatives Bulk-forming laxatives Bulk-forming laxatives Psyllium (Metamucil) Psyllium (Metamucil) Surfactant laxatives Surfactant laxatives Docusate sodium (Colace) Docusate sodium (Colace) Stimulant laxatives Stimulant laxatives Bisacodyl (Dulcolax) Bisacodyl (Dulcolax) Osmotic laxatives Osmotic laxatives Milk of magnesia (MOM) Milk of magnesia (MOM)

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.10 Bulk-Forming Laxatives Function similarly to dietary fiber: swell with water to form a gel to soften fecal mass and increase mass Function similarly to dietary fiber: swell with water to form a gel to soften fecal mass and increase mass Preferred treatment for temporary treatment of constipation Preferred treatment for temporary treatment of constipation Used for diverticulosis and irritable bowel syndrome Used for diverticulosis and irritable bowel syndrome Adverse effects are minimal Adverse effects are minimal Esophageal obstruction Esophageal obstruction

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.11 Surfactant Laxatives Two effects on bowel Two effects on bowel Stimulate intestinal motility Stimulate intestinal motility Increase quantities of water and electrolytes in the intestinal lumen Increase quantities of water and electrolytes in the intestinal lumen Widely used and abused Widely used and abused Legitimately used for opioid-induced constipation and for constipation from slow intestinal transit Legitimately used for opioid-induced constipation and for constipation from slow intestinal transit

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.12 Osmotic Laxatives Laxative salts (magnesium and sodium) Laxative salts (magnesium and sodium) Poorly absorbed salts that draw water into intestinal lumen; fecal mass softens and swells, wall stretches, and peristalsis is stimulated Poorly absorbed salts that draw water into intestinal lumen; fecal mass softens and swells, wall stretches, and peristalsis is stimulated Low doses: results in 6–12 hours Low doses: results in 6–12 hours High doses: results in 2–6 hours High doses: results in 2–6 hours

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.13 Osmotic Laxatives Adverse effects Adverse effects Dehydration: substantial water loss Dehydration: substantial water loss Renal decline: toxicity Renal decline: toxicity Sodium retention: exacerbated heart failure, hypertension, edema Sodium retention: exacerbated heart failure, hypertension, edema

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.14 Other Laxatives Lubiprostone Lubiprostone Selective chloride channel activators Selective chloride channel activators Glycerin suppository Glycerin suppository Mineral oil Mineral oil

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.15 Bowel-Cleansing Products for Colonoscopy Allow for good visualization of the bowel Allow for good visualization of the bowel Two kinds of bowel cleansers Two kinds of bowel cleansers Both equally effective Both equally effective Sodium phosphate Sodium phosphate Hypertonic with body fluids Hypertonic with body fluids Can cause dehydration and electrolyte disturbance Can cause dehydration and electrolyte disturbance Possibility of renal damage Possibility of renal damage Polyethylene glycol (PEG) plus electrolytes (ELS) Polyethylene glycol (PEG) plus electrolytes (ELS) Isotonic with body fluids Isotonic with body fluids Requires ingestion of large volume of bad-tasting liquid Requires ingestion of large volume of bad-tasting liquid

Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.16 Laxative Abuse Causes Causes Misconception that bowel movements must occur daily Misconception that bowel movements must occur daily Can perpetuate their own use Can perpetuate their own use Bowel replenishment after evacuation can be 2–5 days; often mistaken for constipation Bowel replenishment after evacuation can be 2–5 days; often mistaken for constipation Consequences Consequences Diminished defecatory reflexes, leading to further reliance on laxatives Diminished defecatory reflexes, leading to further reliance on laxatives Electrolyte imbalance, dehydration, and colitis Electrolyte imbalance, dehydration, and colitis