Encopresis Medication

Because most children with encopresis have retentive encopresis as a consequence of chronic constipation with resulting overflow incontinence, therapy is initially focused on evacuating the distal colon.^[20] Disimpaction can be accomplished with aggressive use of oral cathartics (eg, polyethylene glycol [PEG], sodium phosphate, magnesium citrate) or a series of enemas. In clinical trials, disimpaction by the oral route or the rectal route is reported to be equally effective.^{[21, 22]}

After the colon is evacuated, long-term laxative therapy is generally started. Virtually any laxative can be used as long as it is used in sufficient quantity to produce 1-2 soft stools per day.

Class Summary

These agents cause fluid retention in the colon, lowering the pH, resulting in distention, and increasing colonic peristalsis.

Polyethylene glycol powder (MiraLax, GlycoLax)

PEG is a long chain of ethylene glycol molecules. The resulting molecule is extremely large, is very poorly absorbed, and functions as an osmotic laxative. These powders are tasteless and odorless and completely dissolve in nearly all liquids including water. These agents 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 (Philip's Milk of Magnesia, Haley's MO)

Magnesium is divalent cation maximally absorbed in distal small intestine. At low concentrations, magnesium appears to be absorbed in saturable carrier-mediated process influenced by vitamin D. At high concentrations, absorption appears to occur largely and inefficiently by diffusion. Increased serum magnesium levels may cause cholecystokinin release, which stimulates GI motility and secretion; may explain why some children have abdominal cramping. Mostly flavorless; thick, chalky texture. Most palatable when mixed with fluid (eg, milk, chocolate milk).

Lactulose (Constilac, Duphalac, Kristalose)

Synthetic nonabsorbable disaccharide. Available as 70% solution. Generally well tolerated and tastes sweet.

Sorbitol

Hyperosmotic laxative. Cathartic actions in GI tract. This alcohol of glucose is largely nonabsorbable. Available as 70% solution. Generally well tolerated and tastes sweet.

Magnesium citrate (Evac-Q-mag)

Magnesium is divalent cation maximally absorbed in the distal small intestine. At low concentrations, magnesium appears to be absorbed in saturable carrier-mediated process influenced by vitamin D. At high concentrations, magnesium absorption appears to occur largely and inefficiently by diffusion. Increased serum magnesium levels may cause cholecystokinin release, which stimulates GI motility and secretion; may explain why some children have abdominal cramping. May be chilled to improve palatability.

Sodium acid phosphate (Fleet Phospho-Soda)

Phosphate is a divalent anion largely absorbed in the proximal small intestine. When administered as an enema, only small amounts are absorbed so 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.

Class Summary

These agents retard colonic absorption of fecal water and thus soften stool.

Mineral oil

Nonabsorbable fat that softens stool and decreases water absorption, partly by its metabolism in colon to hydroxy fatty acids. Largely tasteless and has oily consistency. Most palatable if cold or mixed into a fluid (eg, orange juice). In many children given high doses, causes seepage of orange oil into underwear, which can produce perianal pruritus.

Class Summary

These agents directly act on the intestinal mucosa or nerve plexus. They alter water and electrolyte secretion.

Sennosides (Senokot, Ex-Lax, Fletcher's Castoria, Aloe Vera)

Plant alkaloids that stimulate colonic salt and water secretion and promote colonic motility. Often produce abdominal cramping at high doses. Long-term use in animals not been associated with any evidence of cathartic colon, tachyphylaxis, or secondary hyperaldosteronism.

Bisacodyl (Dulcolax)

Colorless and odorless compound absorbed poorly. Administered PO or PR. Increases colonic peristalsis and stimulates salt and water secretion.

Class Summary

Several days of enemas are often used to evacuate or disimpact the colon before the start of a regular laxative regimen. Various enema preparations can be used to evacuate the distal colon. Most enema preparations contain osmotically active agents that are not substantially absorbed in the colon. Common examples include phosphate (eg, Fleet pediatric, adult enemas), saline, or milk and molasses. To the author's knowledge, no studies have been performed to compare the effectiveness of various enema preparations. In all likelihood, the effectiveness of any particular preparation depends more on the volume of the enema than on the composition of the enema solution.

Sodium acid phosphate (Fleet Enema)

Phosphate is divalent anion absorbed largely in proximal small intestine. Functions as osmotic agent and only small amounts are absorbed when administered as enema.