Laxative
Laxatives, purgatives, or aperients are substances that loosen stools[1] and increase bowel movements. They are used to treat and prevent constipation.
Laxatives vary as to how they work and the side effects they may have. Certain
Types
Bulk-forming agents
Bulk-forming laxatives, also known as
Properties
- Site of action: small and large intestines
- Onset of action: 12–72 hours
- Examples: dietary fiber, FiberCon[3]
Bulk-forming agents generally have the gentlest of effects among laxatives,[1] making them ideal for long-term maintenance of regular bowel movements.
Dietary fiber
Foods that help with laxation include fiber-rich foods.
Emollient agents (stool softeners)
Emollient laxatives, also known as stool softeners, are
Properties
- Site of action: small and large intestines
- Onset of action: 12–72 hours
- Examples: Docusate (Colace, Diocto), Gibs-Eze[3]
Emollient agents prevent constipation rather than treating long-term constipation.[3]
Lubricant agents
Lubricant laxatives are substances that coat the stool with slippery lipids and decrease colonic absorption of water so the stool slides through the colon more easily. Lubricant laxatives also increase the weight of stool and decrease intestinal transit time.[9]
Properties
- Site of action: colon
- Onset of action: 6–8 hours
- Example: mineral oil[9]
Mineral oils, such as liquid paraffin, are generally the only nonprescription lubricant laxative available, but due to the risk of lipid pneumonia resulting from accidental aspiration, mineral oil is not recommended, especially in children and infants.[10][11] Mineral oil may decrease the absorption of fat-soluble vitamins and some minerals.[9]
Hyperosmotic agents
Properties
- Site of action: colon
- Onset of action: 12–72 hours (oral), 0.25–1 hour (rectal)
- Examples: glycerin suppositories (Hallens), sorbitol, lactulose, and PEG (Colyte, MiraLax)[12]
Lactulose works by the osmotic effect, which retains water in the colon; lowering the pH through bacterial fermentation to lactic, formic, and acetic acids; and increasing colonic peristalsis. Lactulose is also indicated in portal-systemic encephalopathy. Glycerin suppositories work mostly by hyperosmotic action, but the sodium stearate in the preparation also causes local irritation to the colon.[citation needed]
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 poisoning. Brand names for these solutions include GoLytely, GlycoLax, Cosmocol, CoLyte, Miralax, Movicol, NuLytely, Suprep, and Fortrans. Solutions of sorbitol (SoftLax) have similar effects.[citation needed]
Saline laxative agents
Saline laxatives are nonabsorbable, osmotically active 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.[3] Saline laxatives may alter a patient's fluid and electrolyte balance.
Properties
- 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)[3]
Stimulant agents
Stimulant laxatives are substances that act on the intestinal
Properties
Prolonged use of stimulant laxatives can create drug dependence by damaging the colon's haustral folds, making users less able to move feces through their 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.[15]
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, small intestine (see below) [citation needed]
- Onset of action: 2–6 hours
- Examples: castor oil[3]
Long-term use of castor oil may result in loss of fluid, electrolytes, and nutrients.[3]
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.
Prucalopride (brand name Resolor) is a current drug approved for use in the EU since October 15, 2009,[17] in Canada (brand name Resotran) since December 7, 2011,[18] and in the United States since December 2018.
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.
Comparison of available agents
Preparation(s) | Type | Site of action | Onset of action |
---|---|---|---|
Cascara (casanthranol ) |
Anthraquinone | colon |
6–8 hours |
Buckthorn |
Anthraquinone | colon | 6–8 hours |
Senna extract (senna glycoside ) |
Anthraquinone | colon | 6–8 hours |
Aloe vera (aloin) | Anthraquinone | colon | 8–10 hours |
Phenolphthalein | Triphenylmethane | colon | 8 hours |
Bisacodyl (oral) | Triphenylmethane | colon | 6–12 hours |
Bisacodyl (suppository) | Triphenylmethane | colon | 60 minutes |
Castor oil | Ricinoleic acid | small intestine | 2–6 hours |
Effectiveness
For adults, a randomized controlled trial found PEG (MiraLax or GlycoLax) 17 grams once per day to be superior to tegaserod at 6 mg twice per day.[21] A randomized controlled trial found greater improvement from two sachets (26 g) of PEG versus two sachets (20 g) of lactulose.[22] 17 g per day of PEG has been effective and safe in a randomized, controlled trial for six months.[23] Another randomized, controlled trial found no difference between sorbitol and lactulose.[24]
For children, PEG was found to be more effective than lactulose.[25]
Problems with use
Laxative abuse
Some of the less significant adverse effects of laxative abuse include
Although some patients with eating disorders such as anorexia nervosa and bulimia nervosa abuse laxatives in an attempt to lose weight, laxatives act to speed up the transit of feces through the large intestine, which occurs after the absorption of nutrients in the small intestine is already complete. Thus, studies of laxative abuse have found that effects on body weight reflect primarily temporary losses of body water rather than energy (calorie) loss.[26][31][32]
Laxative gut
Physicians warn against the chronic use of stimulant laxatives due to concern that chronic use could cause the colonic tissues to get worn out over time and not be able to expel feces due to long-term overstimulation.[33] A common finding in patients having used stimulant laxatives is a brown pigment deposited in the intestinal tissue, known as melanosis coli.[citation needed]
Historical and health fraud uses
Laxatives, once called "physicks" or "purgatives", were used extensively in
See also
References
- ^ a b c d e f "Constipation" (PDF). www.digestive.niddk.nih.gov. National Digestive Diseases Information Clearinghouse. Retrieved 3 November 2014.
- ^ Bulk-forming agent entry in the public domain NCI Dictionary of Cancer Terms
- ^ ISBN 978-1582120744.
- ^ a b c "The Facts About Fiber" (PDF). www.aicr.org. American Institute for Cancer Research. Archived from the original (PDF) on 3 November 2014. Retrieved 3 November 2014.
- ^ Das, JL (2010). "Medicinal and nutritional values of banana cv. NENDRAN". Asian Journal of Horticulture. 8: 11–14. Archived from the original on 2014-11-03. Retrieved 2012-11-29.
- ^ "15 Foods That Cause Constipation (Caffeine, Chocolate, Alcohol)". MedicineNet. Retrieved 2017-12-12.
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- ^ ISBN 978-1582120744.
- ^ ISBN 978-1-58212-317-2.)
{{cite book}}
: CS1 maint: location (link - ^ Bowles-Jordan, Jane. "Constipation". CPS. Retrieved March 20, 2020.
- ^ ISBN 978-1582120744.
- Mayo clinic. Last updated: Nov. 1, 2012
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- ^ Research, Center for Drug Evaluation and. "Postmarket Drug Safety Information for Patients and Providers - Zelnorm (tegaserod maleate) Information". www.fda.gov. Retrieved 14 April 2018.
- ^ "European Medicines Agency EPAR summary for the public" (PDF). europa.eu. Archived from the original (PDF) on 14 April 2018. Retrieved 14 April 2018.
- ^ "Health Canada, Notice of Decision for Resotran". hc-sc.gc.ca. Archived from the original on 18 March 2017. Retrieved 14 April 2018.
- ^ Dharmananda, Subhuti. "SAFETY ISSUES AFFECTING HERBS: How Long can Stimulant Laxatives be Used?". Institute for Traditional Medicine. Retrieved 2010-03-19.
- ^ "Stimulant Laxatives". Family Practice Notebook, LLC. 2010-02-26. Retrieved 2010-03-19.
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- ^ "BestBETs: Is polyethylene glycol safe and effective for chro..." Retrieved 2007-09-06.
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- ^ "Acid-base and electrolyte abnormalities with diarrhea". www.uptodate.com. Retrieved 2017-12-12.
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