Laxatives: Difference between revisions
 
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==Types==
==Types==
[[File:Diameters of the large intestine.png|thumb|Average inner diameters and ranges of different sections of the large intestine.<ref> Nguyen H, Loustaunau C, Facista A, Ramsey L, Hassounah N, Taylor H, et al. (July 2010). "Deficient Pms2, ERCC1, Ku86, CcOI in field defects during progression to colon cancer". Journal of Visualized Experiments (41). doi:10.3791/1931. PMC 3149991. PMID 20689513.</ref>]]
===Bulk-forming agents===
===Bulk-forming agents===
Bulk-forming laxatives, also known as roughage, are substances, such as dietary fiber and hydrophilic agents that add bulk and water to more easily through the intestines.<ref>[http://www.cancer.gov/dictionary?CdrID=489403 Bulk-forming agent] entry in the public domain NCI Dictionary of Cancer Terms</ref>
''Substances, such as dietary fiber and hydrophilic agents that add bulk and water to more easily through the intestines.''


'''Properties'''
*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.''


'''Properties'''
*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===
{{main|Lubricant}}
''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.''
Lubricant laxatives are substances that 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.<ref name=Handbook/>


'''Properties'''
*Site of action: colon
*Site of action: colon
*Onset of action: 6–8 hours
*Onset of action: 6–8 hours
*Example: mineral oil<ref name=Handbook/>
*Example: mineral oil


Mineral oil is the only nonprescription lubricant. Mineral oil may decrease the absorption of fat-soluble vitamins and some minerals.<ref name=Handbook/>
===Hyperosmotic agents===
''Substances that cause the intestines to hold more water within and create an osmotic effect that stimulates a bowel movement.''


===Hyperosmotic agents===<!-- This section is linked from [[Glycerol]] -->
Hyperosmotic laxatives are substances that cause the intestines to hold more water within and create an osmotic effect that stimulates a bowel movement.<ref name=Handbook/>
'''Properties'''
*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)
*Examples: [[glycerin]] suppositories, [[sorbitol]], [[lactulose]], and [[polyethylene glycol|PEG]] (Colyte, MiraLax)<ref name=Handbook/>
*Examples: [[glycerin]] suppositories, [[sorbitol]], [[lactulose]], and [[Polyethylene glycol 3350|PEG]] (Colyte, MiraLax)
 
[[Lactulose]] works by the osmotic effect, which retains water in the colon, lowering the [[pH]] through bacterial fermentation to lactic, formic and acetic acid, and increasing colonic [[peristalsis]]. Lactulose is also indicated in [[Hepatic encephalopathy|portal-systemic encephalopathy]]. Glycerin suppositories work mostly by hyperosmotic action, but the [[sodium stearate]] in the preparation also causes local irritation to the colon.
 
Solutions of polyethylene glycol and electrolytes ([[sodium chloride]], [[sodium bicarbonate]], [[potassium chloride]], and sometimes [[sodium sulfate]]) are used for [[whole bowel irrigation]], a process designed to prepare the bowel for surgery or [[colonoscopy]] and to treat certain types of [[poison]]ing. Brand names for these solutions include GoLytely, GlycoLax, CoLyte, Miralax, Movicol, NuLytely, Suprep, and Fortrans. Solutions of [[sorbitol]] (SoftLax) have similar effects.


===Saline laxative agents===
===Saline laxative agents===
Saline laxatives are 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.<ref name=Handbook/> Saline laxatives may alter a patient's fluid and electrolyte balance.
''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.''


'''Properties'''
*Site of action: small and large intestines
*Site of action: small and large intestines
*Onset of action: 0.5–3 hours (oral), 2–15 minutes (rectal)
*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)<ref name=Handbook/>
*Examples: sodium phosphate (and variants), [[magnesium citrate]], [[magnesium hydroxide]] (milk of magnesia), and [[magnesium sulfate]] (Epsom salt)
 
Saline laxatives should be taken with plenty of water.


===Stimulant agents===
===Stimulant agents===
Stimulant laxatives are substances that act on the intestinal [[mucosa]] or [[nerve plexus]], altering water and [[electrolyte]] secretion.<ref>[http://www.mayoclinic.com/health/drug-information/DR602359 Laxative (Oral Route)] from [[Mayo clinic]]. Last updated: Nov. 1, 2012</ref> They also stimulate peristaltic action and can be dangerous under certain circumstances.<ref name=pmid9649012>{{cite journal |vauthors=Joo JS, Ehrenpreis ED, Gonzalez L, Kaye M, Breno S, Wexner SD, Zaitman D, Secrest K | title = Alterations in colonic anatomy induced by chronic stimulant laxatives: the cathartic colon revisited | journal = J Clin Gastroenterol | volume = 26 | issue = 4 | pages = 283–6 | year = 1998 | pmid = 9649012 | doi = 10.1097/00004836-199806000-00014 }}</ref>
''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.''


'''Properties'''
*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]]<ref name=Handbook/>
*Examples: [[senna]] glycoside, [[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
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</ref>


===Miscellaneous===
===Miscellaneous===
[[Castor oil]] is a glyceride that is hydrolyzed by pancreatic lipase to ricinoleic acid, which produces laxative action by an unknown mechanism.
''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
*Site of action: colon
*Onset of action: 2–6 hours
*Onset of action: 2–6 hours
*Examples: castor oil<ref name=Handbook/>
*Examples: castor oil
 
Long-term use of castor oil may result in loss of fluid, electrolytes, and nutrients.<ref name=Handbook/>
 
===Serotonin agonist===
These are motility stimulants that work through activation of [[serotonin|5-HT<sub>4</sub>]] 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.<ref>[http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm103223.htm Tegaserod, FDA Zelnorm (tegaserod maleate) Information]</ref>
 
[[Prucalopride]] (brand name Resolor) is a current
drug approved for use in the EU October 15, 2009<ref>[http://www.emea.europa.eu/docs/en_GB/document_library/EPAR_-_Summary_for_the_public/human/001012/WC500053995.pdf European Medicines Agency EPAR summary for the public]</ref> and in Canada (brand name Resotran) on December 7, 2011.<ref>[http://www.hc-sc.gc.ca/dhp-mps/prodpharma/sbd-smd/drug-med/sbd_smd_2012_resotran_141157-eng.php#a2 Health Canada, Notice of Decision for Resotran]</ref> 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|Shire PLC]].<ref>http://www.shire.com/shireplc/en/rd/pipeline Shire PLC, R and D projects, Resolor</ref>
 
===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==
==See Also==
*[[Constipation]]
*[[Constipation (Peds)]]


==References==
==References==
<references/>
<references/>
[[Category:Pharmacology]]
[[Category:GI]]

Latest revision as of 21:02, 24 September 2025

Types

Average inner diameters and ranges of different sections of the large intestine.[1]

Bulk-forming agents

Substances, such as dietary fiber and hydrophilic agents that add bulk and water to more easily through the intestines.

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.

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
  • Onset of action: 6–10 hours
  • Examples: senna glycoside, bisacodyl

Miscellaneous

Castor oil is a glyceride that is hydrolyzed by pancreatic lipase to ricinoleic acid, which produces laxative action by an unknown mechanism.

  • Site of action: colon
  • Onset of action: 2–6 hours
  • Examples: castor oil

See Also

References

  1. ↑ Nguyen H, Loustaunau C, Facista A, Ramsey L, Hassounah N, Taylor H, et al. (July 2010). "Deficient Pms2, ERCC1, Ku86, CcOI in field defects during progression to colon cancer". Journal of Visualized Experiments (41). doi:10.3791/1931. PMC 3149991. PMID 20689513.
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