The efficacy and safety of polyethylene glycol 3350 in the treatment of constipation in children

Pediatric Nursing, May-June, 2004 by Margo A. Kinservik, Margaret M. Friedhoff

Study #2. Pashankar and Bishop (2001) conducted a study to determine the efficacy and optimal dose of MiraLax for the treatment of constipation in children. This was a prospective study with no control or comparison group. Twenty-four children between the ages of 18 months and 12 years with the diagnosis of chronic constipation were enrolled in this study at a large referral center. Four subjects were dropped from the study because they failed to return the symptom diaries. The 20 remaining children ranged in age from 18 months to 11 years (mean age 6.09 [ or -] 4.2 years.). Of these children, 11 had constipation without encopresis, and 9 had constipation with encopresis. The mean duration of their constipation was 3.14 years. Most patients had been treated with laxatives, stool softeners, fiber supplements, or rectal medications in the past. Children were excluded if they had a history of (a) anorectal malformations, (b) abdominal surgery, (c) Hirschsprung's disease, or (d) any illness that could cause constipation.

The pathophysiology of constipation as well as the rationale of treatment was explained to the parents, and they were asked to keep a symptom diary. Children were advised to sit on the toilet for 5 minutes after each meal. The bowel habits before treatment with MiraLax were compared to the bowel habits recorded in the last 2 weeks of treatment with MiraLax. The children in the study were placed on MiraLax for 8 weeks.

All study subjects reported rapid improvement in their stooling during treatment with MiraLax. The stool frequency per week of the children treated increased from 2.3 [ or -] 0.4 to 16.9 [ or -] 1.6 (p < .0001). Four of the nine children with encopresis stopped soiling. Other improvements in symptoms on MiraLax included less pain and fear associated with stooling and the disappearance of blood on the stools. All children were willing to take the MiraLax, and the families did not report a problem with palatability.

Minimal side effects were reported. Two children reported an increase in flatus, which could have been caused by the sucrose-containing liquid that they both mixed with the MiraLax. One patient complained of mild abdominal pain for 1 week. That child's abdominal pain disappeared during treatment. No patients stopped the MiraLax because of adverse symptoms or taste. Of the 16 study participants who had been on other laxatives in the past, all decided to stay on the MiraLax after the study ended.

To arrive at an effective dose of MiraLax, patients were started on a dose of ~ 1 g/kg/day divided into 2 doses. Starting the children on this dose resulted in disimpaction without the use of rectal or stimulant medications. Parents were then instructed to adjust the dose by small increments to achieve 2 soft stools per day. The investigators found that the mean effective dose of MiraLax was 0.84 g/kg/day, although the range among subjects was 0.27 to 1.42 g/kg/day. The authors suggest that adjustments to the dose should be made as necessary during therapy.