Comparison of Efficacy & Tolerability Of PEG 4000 Versus PEG 3350+ Electrolytes for Pediatric Fecal Disimpaction

Childhood constipation is a common but serious gastrointestinal disorder prevalent worldwide. In approximately 90-95% of children, it is of functional origin i.e., without an identifiable organic pathology. It accounts for 3% of pediatric outpatient visits and 25% of referrals to a pediatric gastroenterologist. Prevalence rates ranging from 0.7% to 29.6% with a median of 8.9% have been described in the older literature, with a higher prevalence in Asian population. However, in a recent study, using the Rome IV criteria, the pooled global prevalence of pediatric functional constipation is found to be 14.4% (95%CI: 11.2-17.6). Severe longstanding constipation is distressing for the entire family and poses a substantial psychological, social, and educational strain on the child's development.

Thirty to seventy-five percent of children with functional constipation also have fecal impaction. It typically begins after several bouts of painful bowel movements, which triggers a vicious cycle of fear-induced stool-withholding behavior leading to more stool retention. Consequently, a significant amount of feces accumulates in the rectum forming a big fecal mass or fecaloma, causing a variety of complaints, including gastrointestinal discomfort, excessive flatulence, nausea or vomiting, poor appetite, mood swings \& irritability. European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) \& the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) position paper on pediatric constipation defines fecal impaction as any one of the following: i) palpation of a hard mass in the lower abdomen on physical examination, ii) a dilated rectum filled with a large amount of stool on rectal examination, iii) abdominal radiography showing excessive stool in the distal colon.

The treatment strategy for functional constipation includes fecal disimpaction and maintenance therapy to ensure regular bowel movements. ESPGHAN \& NASPGHAN guidelines emphasize that maintenance therapy remains ineffective until disimpaction has been achieved. If initial disimpaction is skipped, oral laxative therapy may paradoxically worsen fecal incontinence/encopresis attributable to overflow diarrhea.

Polyethylene glycol (PEG) based laxatives have been recommended as the first-line therapeutic agents for both disimpaction as well as maintenance therapy in childhood functional constipation. PEG, a biologically inert polymer of the formula H(OCH2CH2)nOH in which n is 68-84. These are non-absorbable polymers, that create an osmotic gradient in the intestinal lumen leading to fluid retention which in turn softens and loosens the stool. Hence, they act as osmotic laxatives. As it does not carry any electrical charge, it does not influence the movement of any other solutes. The commonly used formulations are PEG 3350 with a molecular weight between 3200 and 3700 g/mol and PEG 4000 with an approximate molecular weight of 4000 g/mol. Both are shown to be effective in pediatric constipation management in placebo-controlled trials. However, there is scanty literature available comparing other aspects of various PEG formulations, such as tolerability, palatability, \& convenience of administration, which may affect treatment adherence and thus the ultimate treatment outcome. PEG + Electrolyte (E) is more widely used than PEG for the management of constipation. This might be because of the perception that PEG + E is safer in terms of preventing electrolyte imbalance.

However, several head-to-head trials using different PEG formulations in adult constipation patients, showed comparable efficacy and safety. Because of the inclusion of electrolytes, PEG+E tastes saltier than PEG. Many patients struggle to tolerate the unpleasant taste resulting in the high incidence of non-compliance and treatment failure . Two studies from the adult population have demonstrated better acceptance of PEG in comparison to PEG+E . In fact, the latest meta-analysis concluded that the addition of electrolytes to PEG does not provide any clinical benefits over PEG alone.

In a recent double-blind RCT, PEG 4000 is found to be equally efficacious and safe as PEG 3350 + E as a long-term maintenance therapy in children with functional constipation . However, they have not described the tolerability or acceptability data of the cohort. There is only a single pediatric study that showed, PEG 4000 is equally effective and had a higher patient acceptance rate owing to significantly lesser nausea, vomiting episodes, and better palatability compared to PEG 3350. However, both these studies are majorly focused on the comparison between PEG 3350 + E versus PEG 4000 as a long-term maintenance therapy in pediatric functional constipation. There is only a single study that compared PEG 3350 versus PEG 3350 only laxative for fecal disimpaction. Both of them were found to almost equally effective in resolution of fecal impaction, however PEG 3350 + E group had significantly higher side effects as compared to PEG 3350 only laxative.

To date, no pediatric trials have compared PEG versus PEG+E on a head-to-head basis for the treatment of the initial but most important \& crucial step of pediatric function constipation management i.e. Fecal disimpaction. Since fecal disimpaction requires administration of a significantly larger volume of PEG administration, palatability becomes a major factor determining the success of disimpaction. On the other hand, there is also of higher possibility of side effects like electrolyte \& acid base imbalances because of higher purge rate during disimpaction. Comparison of both these parameters namely tolerability/palatability and safety/side effects profile of PEG versus PEG + E during fecal disimpaction in pediatric population has not been studied previously.

Therefore, the present study has been planned with an aim to evaluate the efficacy \& tolerability of PEG 4000 versus PEG 3350+ electrolytes for fecal disimpaction in paediatric functional constipation.