Laxatives: Difference between revisions
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==Types== | ==Types== | ||
===Bulk-forming agents=== | ===Bulk-forming agents=== | ||
''Substances, such as dietary fiber and hydrophilic agents that add bulk and water to more easily through the intestines.'' | |||
*Site of action: Small and large intestines | *Site of action: Small and large intestines | ||
*Onset of action: 12–72 hours | *Onset of action: 12–72 hours | ||
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===Emollient agents (stool softeners)=== | ===Emollient agents (stool softeners)=== | ||
Anionic surfactants that enable additional water and fats to be incorporated in the stool, making it easier for them to move through the gastrointestinal tract. | ''Anionic surfactants that enable additional water and fats to be incorporated in the stool, making it easier for them to move through the gastrointestinal tract.'' | ||
*Site of action: small and large intestines | *Site of action: small and large intestines | ||
*Onset of action: 12–72 hours | *Onset of action: 12–72 hours | ||
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===Lubricant agents=== | ===Lubricant agents=== | ||
Coat the stool with slippery lipids and retard colonic absorption of water so that the stool slides through the colon more easily. Lubricant laxatives also increase the weight of stool and decrease intestinal transit time. | ''Coat the stool with slippery lipids and retard colonic absorption of water so that the stool slides through the colon more easily. Lubricant laxatives also increase the weight of stool and decrease intestinal transit time.'' | ||
*Site of action: colon | *Site of action: colon | ||
*Onset of action: 6–8 hours | *Onset of action: 6–8 hours | ||
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===Hyperosmotic agents===<!-- This section is linked from [[Glycerol]] --> | ===Hyperosmotic agents===<!-- This section is linked from [[Glycerol]] --> | ||
Substances that cause the intestines to hold more water within and create an osmotic effect that stimulates a bowel movement. | ''Substances that cause the intestines to hold more water within and create an osmotic effect that stimulates a bowel movement.'' | ||
*Site of action: colon | *Site of action: colon | ||
*Onset of Action: 12–72 hours (oral) 0.25 - 1 hour (rectal) | *Onset of Action: 12–72 hours (oral) 0.25 - 1 hour (rectal) | ||
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===Saline laxative agents=== | ===Saline laxative agents=== | ||
Non-absorbable osmotic substances that attract and retain water in the intestinal lumen, increasing intraluminal pressure that mechanically stimulates evacuation of the bowel. Magnesium-containing agents also cause the release of cholecystokinin, which increases intestinal motility and fluid secretion. | ''Non-absorbable osmotic substances that attract and retain water in the intestinal lumen, increasing intraluminal pressure that mechanically stimulates evacuation of the bowel. Magnesium-containing agents also cause the release of cholecystokinin, which increases intestinal motility and fluid secretion.'' | ||
*Site of action: small and large intestines | *Site of action: small and large intestines | ||
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===Stimulant agents=== | ===Stimulant agents=== | ||
Act on the intestinal mucosa or nerve plexus, altering water and [[electrolyte]] secretion. They also stimulate peristaltic action and can be dangerous under certain circumstances. | |||
*Site of action: colon | *Site of action: colon | ||
*Onset of action: 6–10 hours | *Onset of action: 6–10 hours | ||
*Examples: [[senna glycoside|senna]], [[bisacodyl]] | *Examples: [[senna glycoside|senna]], [[bisacodyl]] | ||
They are the most powerful among laxatives and should be used with care. Prolonged use of stimulant laxatives can create drug dependence by damaging the colon's [[Haustrum (anatomy)|haustral folds]], making a user less able to move feces through the colon on their own. A study of patients with chronic constipation found that 28% of chronic stimulant laxative users lost haustral folds over the course of one year, while none of the control group did.<ref>Alterations in Colonic Anatomy Induced by Chronic Stimulant Laxatives: The Cathartic Colon Revisited | They are the most powerful among laxatives and should be used with care. Prolonged use of stimulant laxatives can create drug dependence by damaging the colon's [[Haustrum (anatomy)|haustral folds]], making a user less able to move feces through the colon on their own. A study of patients with chronic constipation found that 28% of chronic stimulant laxative users lost haustral folds over the course of one year, while none of the control group did.<ref>Alterations in Colonic Anatomy Induced by Chronic Stimulant Laxatives: The Cathartic Colon Revisited | ||
Revision as of 03:52, 1 August 2016
Types
Bulk-forming agents
Substances, such as dietary fiber and hydrophilic agents that add bulk and water to more easily through the intestines.
- Site of action: Small and large intestines
- Onset of action: 12–72 hours
- Examples: dietary fiber, psyllium (Metamucil), methylcellulose (Citrucel), polycarbophil (FiberCon)
Dietary fiber
Includes insoluble fiber and soluble fiber, such as:
- Fruits, such as bananas, kiwifruits, prunes, apples (with skin), pears (with skin), and raspberries
- Vegetables, such as broccoli, string beans, kale, spinach, cooked winter squash, cooked green peas, and baked potatoes (with skin)
- Whole grains
- Bran products
- Nuts
- Legumes, such as beans, peas, and lentils
Emollient agents (stool softeners)
Anionic surfactants that enable additional water and fats to be incorporated in the stool, making it easier for them to move through the gastrointestinal tract.
- Site of action: small and large intestines
- Onset of action: 12–72 hours
- Examples: docusate (Colace, Diocto), Gibs-Eze
Lubricant agents
Coat the stool with slippery lipids and retard colonic absorption of water so that the stool slides through the colon more easily. Lubricant laxatives also increase the weight of stool and decrease intestinal transit time.
- Site of action: colon
- Onset of action: 6–8 hours
- Example: mineral oil
Hyperosmotic agents
Substances that cause the intestines to hold more water within and create an osmotic effect that stimulates a bowel movement.
- Site of action: colon
- Onset of Action: 12–72 hours (oral) 0.25 - 1 hour (rectal)
- Examples: glycerin suppositories, sorbitol, lactulose, and PEG (Colyte, MiraLax)
Saline laxative agents
Non-absorbable osmotic substances that attract and retain water in the intestinal lumen, increasing intraluminal pressure that mechanically stimulates evacuation of the bowel. Magnesium-containing agents also cause the release of cholecystokinin, which increases intestinal motility and fluid secretion.
- Site of action: small and large intestines
- Onset of action: 0.5–3 hours (oral), 2–15 minutes (rectal)
- Examples: sodium phosphate (and variants), magnesium citrate, magnesium hydroxide (milk of magnesia), and magnesium sulfate (Epsom salt)
Stimulant agents
Act on the intestinal mucosa or nerve plexus, altering water and electrolyte secretion. They also stimulate peristaltic action and can be dangerous under certain circumstances.
They are the most powerful among laxatives and should be used with care. Prolonged use of stimulant laxatives can create drug dependence by damaging the colon's haustral folds, making a user less able to move feces through the colon on their own. A study of patients with chronic constipation found that 28% of chronic stimulant laxative users lost haustral folds over the course of one year, while none of the control group did.[1]
Miscellaneous
Castor oil is a glyceride that is hydrolyzed by pancreatic lipase to ricinoleic acid, which produces laxative action by an unknown mechanism.
Properties
- Site of action: colon
- Onset of action: 2–6 hours
- Examples: castor oil[2]
Long-term use of castor oil may result in loss of fluid, electrolytes, and nutrients.[2]
Serotonin agonist
These are motility stimulants that work through activation of 5-HT4 receptors of the enteric nervous system in the gastrointestinal tract. However, some have been discontinued or restricted due to potentially harmful cardiovascular side-effects.
Tegaserod (brand name Zelnorm) was removed from the general U.S. and Canadian markets in 2007, due to reports of increased risks of heart attack or stroke. It is still available to physicians for patients in emergency situations that are life-threatening or require hospitalization.[3]
Prucalopride (brand name Resolor) is a current drug approved for use in the EU October 15, 2009[4] and in Canada (brand name Resotran) on December 7, 2011.[5] It has not been approved by the Food and Drug Administration for use in the United States, but it is in development by Shire PLC.[6]
Chloride channel activators
Lubiprostone is used in the management of chronic idiopathic constipation and irritable bowel syndrome. It causes the intestines to produce a chloride-rich fluid secretion that softens the stool, increases motility, and promotes spontaneous bowel movements (SBM).
See Also
References
- ↑ Alterations in Colonic Anatomy Induced by Chronic Stimulant Laxatives: The Cathartic Colon Revisited Joo et al. Journal of Clinical Gastroenterology. June 1998 Volume 26 Issue 4 pp 283 - 286. http://journals.lww.com/jcge/Abstract/1998/06000/Alterations_in_Colonic_Anatomy_Induced_by_Chronic.14.aspx
- ↑ 2.0 2.1 Cite error: Invalid
<ref>tag; no text was provided for refs namedHandbook - ↑ Tegaserod, FDA Zelnorm (tegaserod maleate) Information
- ↑ European Medicines Agency EPAR summary for the public
- ↑ Health Canada, Notice of Decision for Resotran
- ↑ http://www.shire.com/shireplc/en/rd/pipeline Shire PLC, R and D projects, Resolor