Medication Summary
In several randomized trials, laxatives have been shown to be beneficial in the treatment of chronic childhood constipation. [32, 33] Studies have also shown that polyethylene glycol, [34] mineral oil, magnesium hydroxide, and lactulose are effective and can be used for prolonged time periods without risk.
The key to pharmacotherapy is to use a sufficient amount of laxative to produce the desired effect. The intermittent use of stimulant laxatives may be necessary in some children; however, routine usage of these agents in young children is not generally recommended. Continuous laxative therapy may be required for a number of months until the association between pain and the passage of bowel movements has been extinguished.
Osmotic Laxatives
Class Summary
Osmotic laxatives produce an osmotic effect in the colon that results in distention and promotes peristalsis.
Polyethylene glycol (MiraLAX, Dulcolax Balance)
Polyethylene glycol (PEG) is a long chain of ethylene glycol molecules that results in an extremely large molecule. This agent is very poorly absorbed and functions as an osmotic laxative. The powders are tasteless and odorless and dissolve completely in nearly all liquids including water.
These agents often can also be used as purgatives in preparation for colonoscopy. At very large dosages, PEG is occasionally difficult to take and its usage may be associated with nausea, bloating, abdominal cramps, and vomiting.
Magnesium hydroxide (Philips' Milk of Magnesia, Fleet Pedia-Lax)
Magnesium is a divalent cation that is maximally absorbed in the distal small intestine. At low concentrations, magnesium appears to be absorbed by a saturable carrier-mediated process influenced by vitamin D. At higher concentrations, magnesium absorption appears to occur largely by diffusion and is quite inefficient. Increased serum magnesium levels may release cholecystokinin, which stimulates gastrointestinal motility and secretion; this may explain why some children experience abdominal cramping.
Magnesium is mostly flavorless but has a thick, chalky texture. It is made more palatable when mixed with a fluid (eg, milk, chocolate milk).
Lactulose (Constulose, Enulose, Generlac, Kristalose)
Lactulose is a synthetic, nonabsorbable disaccharide that is available as a 70% solution. This agent is generally very well tolerated and tastes sweet. Lactulose formulation contains 10 g lactulose/15 mL of oral solution. Bloating, borborygmi, and flatulence are common side effects as a result of colonic flora fermenting the lactulose.
Sorbitol
Sorbitol is an alcohol of glucose that is largely nonabsorbable. This agent is available as a 70% solution. As with lactulose, sorbitol is generally well tolerated and tastes quite sweet. Bloating, borborygmi, and flatulence are common side effects as a result of colonic flora fermenting the sorbitol.
Magnesium citrate (Citroma)
Magnesium is a divalent cation that is maximally absorbed in the distal small intestine. At low concentrations, magnesium appears to be absorbed by a saturable carrier-mediated process influenced by vitamin D. At higher concentrations, magnesium absorption appears to occur largely by diffusion and is quite inefficient. Increased serum magnesium levels may release cholecystokinin, which stimulates gastrointestinal motility and secretion; this may explain why some children experience abdominal cramping.
Sodium acid phosphate (OsmoPrep, Visicol)
Phosphate is a divalent anion largely absorbed in the proximal small intestine. When this agent is administered as an enema, only small amounts are absorbed such that the phosphate functions as an osmotic agent. Each 15 mL contains 7.2 g monobasic sodium phosphate monohydrate and 2.7 g dibasic sodium phosphate heptahydrate.
Lubricants
Class Summary
Lubricating agents soften stools and decrease water absorption from the gastrointestinal tract. They may also promote salt and water secretion by the colon.
Mineral oil (Kondremul)
Mineral oil is a nonabsorbable fat that softens stool and decreases water absorption, partly by its metabolism in the colon to hydroxy fatty acids. This agent is largely tasteless and has an oily consistency that is made more palatable if it is cold or mixed into a fluid (eg, orange juice). When mineral oil is taken in high doses, many children experience seepage of orange oil into their underwear, which can produce perianal pruritus.
Stimulant Laxatives
Class Summary
Stimulant laxatives increase peristaltic activity in the gastrointestinal tract. Most of these agents also stimulate salt and water secretion in the colon.
Senna (Ex-Lax, Senokot, Fletcher's, Little Tummys)
Sennosides are plant alkaloids that stimulate colonic salt and water secretion and promote colonic motility. At higher doses, these agents often produce abdominal cramping. Long-term use in animals has not been associated with any evidence of cathartic colon, tachyphylaxis, or secondary hyperaldosteronism.
Bisacodyl (Dulcolax, Bisco-Lax)
Bisacodyl is a colorless and odorless compound that is very poorly absorbed. This agent can be administered orally or rectally. Bisacodyl increases colonic peristalsis and stimulates salt and water secretion.
Stool Softeners
Class Summary
Stool softening agents allow incorporation of water and fat into the stool, causing the stool to soften.
Docusate sodium (Colace, Docu-Soft, Diocto, DSS)
Docusate sodium is used to avoid straining during defecation. This agent allows incorporation of water and fat into the stool, causing it to soften.
Stool Softeners in Combination With Stimulants
Class Summary
Emollient stool softeners cause stool to soften. Stimulants increase peristaltic activity in the gastrointestinal tract. Most of both these types of agents also promote salt and water secretion by the colon.
Senna concentrate/docusate (Peri-Colace, Senokot, Dok Plus)
Docusate sodium allows incorporation of water and fat into the stool, causing it to soften. Casanthranol is an anthraquinone stimulant hydrolyzed by colonic bacteria into an active compound. Action is usually produced 8-12 hours after administration of this combination.
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Plain abdominal radiograph that demonstrates stool throughout the colon.
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This table differentiates functional constipation from Hirschsprung disease.
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This unprepared single-contrast barium enema demonstrates a transition zone consistent with Hirschsprung disease.
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The images illustrate normal anorectal manometry with relaxation of the internal anal sphincter in response to rectal distention.
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This image delineates common withholding behaviors in young children.
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Contrast enema of a patient with megasigmoid and impacted stool.
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Contrast enema in a patient in whom the rectosigmoid was resected.
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Position for enema administration in an infant.
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Another position for enema administration.
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Administration of an enema.
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Incorrect enema administration. The enema is administered against stool impaction and cannot be successful.
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Enema administration with a tube.
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Enema with inflated Foley balloon catheter.
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Administration of an enema against impacted stool.
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Administration of an enema against fecal impaction.
