Which medications in the drug class Osmotic Laxatives are used in the treatment of Pediatric Constipation?

Updated: Dec 14, 2018
  • Author: Stephen M Borowitz, MD; Chief Editor: Carmen Cuffari, MD  more...
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Answer

Osmotic Laxatives

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.


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