Drugs for Constipation (Purgatives or Laxatives ) Prof. Alhaider Dept. of Pharmacology 1434 H.
Chapter 26 Laxatives and Antidiarrheals. Copyright 2007 Thomson Delmar Learning, a division of...
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Transcript of Chapter 26 Laxatives and Antidiarrheals. Copyright 2007 Thomson Delmar Learning, a division of...
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
26 - 2
Laxative Classifications
Stimulant Saline Bulk-forming Lubricant
Stool softeners Suppositories
Lactulose Enemas
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
26 - 3
Stimulant Laxatives
Action Chemical irritation
Increase motility of the GI tract Increase secretion of water into large and
small intestine Example: bisacodyl
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
26 - 4
Saline Laxatives
Increase osmotic pressure within the intestinal tract
Cause more water to enter the intestines Result in:
Bowel distention, increased peristalsis, and evacuation
(continues)
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
26 - 5
Saline Laxatives
Contain salt Unpleasant taste Systemically absorbed Result in:
Poor client compliance Risk for dehydration Risk for congestive heart failure
(continued)
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
26 - 6
Bulk-Forming Laxatives
Safest form Absorbs water to increase bulk Distends bowel to initiate reflex bowel activity
Not systemically absorbed High fiber Natural or semisynthetic
Examples: psyllium hydrophilic muciloid (Metamucil), methylcellulose (Citrucel), and polycarbophil (Fibercon)
(continues)
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26 - 7
Bulk-Forming Laxatives
Must be followed with a large amount of fluid
If chewed or taken in dry powder form, these agents can cause esophageal obstruction and/or fecal impaction.
(continued)
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
26 - 8
Lubricant Laxatives
Oils lubricate the fecal material and intestinal walls, thereby promoting fecal passage:
Prevent fat-soluble vitamins from being absorbed
Popular lubricant Mineral oil (liquid petroleum)
Not digested or absorbed
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26 - 9
Stool Softeners
Detergent-like drugs: Permit mixing of fats and fluids with the
fecal mass Stool becomes softer and is passed much
easier Takes several days to work
Example: docusate salts (Colace and Surfak)
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26 - 10
Suppositories
Usually in a wax base Administered rectally Absorbed systemically Available containing stimulant drugs
Glycerin Absorbs water from tissues, creating more mass
Bisacodyl Induces peristaltic contraction by direct stimulation
of sensory nerves
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26 - 11
Lactulose Laxatives
Two monosaccharides that are not digested or absorbed
Digested in the colon by bacteria to form acids substances
Acid substances cause water to be drawn into the colon
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26 - 12
GoLYTELY
Polyethylene glycol (electrolyte solution and salt)
Must consume 4 liters within 3 hours Causes a large volume of water to be
retained in the colon Acts within one hour
Produces a diarrheal state
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26 - 13
Enemas
Hyperosmotics Solution contain salts (e.g., Fleet enema)
Administered rectally and cause a laxative effect by osmotically drawing fluid into the colon to initiate defecation
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26 - 14
Long-Term Use
Long-term use of laxatives often results in decreased bowel tone and may lead to dependency.
Encourage A healthy, high-fiber diet Increased fluid intake
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26 - 15
Adsorbents
Most commonly used Claylike materials administered in a
tablet or liquid suspension form after each loose bowel movement
Bind to the causative bacteria or toxin, and are eliminated through the stool
Little scientific proof that they work Examples: kaolin-pectin, attapulgite
(Kaopectate)
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26 - 16
Antidiarrheals
Reduce GI motility Opium is a narcotic.
Decreases bowel motility and rectal spasms Depresses the CNS; monitor closely Decreases transit time through the bowel;
more time for water and electrolytes to be absorbed
Paregoric is an opium tincture. May cause physical dependence
(continues)
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26 - 17
Antidiarrheals
Loperarmide HCl (Imodium) Made from chemicals related to meperidine,
a narcotic Diphenoxylate HCl and atropine sulfate
(Lomotil) Narcotic and anticholinergic drug
Reduces GI motility
(continued)
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26 - 18
Anticholinergics
Decrease intestinal muscle tone and peristalsis of GI tract
Result: slows the movement of fecal matter through the GI tract
Example: belladonna alkaloids (Donnatal)