A study was conducted in 2016 to examine all the published literature on the use of polyethylene glycol (PEG), with or without electrolytes, in the management of functional constipation in children and adults and fecal impaction.Data was sourced from MEDLINE, EMBASE and Cochrane databases. All the articles were segregated according to age – adult and children and also as per the type of articles, whether studies, review articles or meta-analysis. Articles were also categorized according to the comparison trials of PEG with other laxatives. However, the study design, methodology, variables examined and sample size differed between the studies included.

Twenty-six trials on the use of PEG in adults were reviewed. Of these, 17 were clinical trials, 4 were observational studies, while the rest were two review articles and three meta-analyses. In these trials, PEG was compared with placebo, lactulose, tegaserod, prucalopride and psyllium. Tegaserod has been withdrawn because of cardiovascular side effects.Attar et al demonstrated the superiority of PEG 3350+E over lactulose for treatment of chronic constipation. The number of stools per week was higher with PEG vs lactulose (1.3 vs 0.9) and in the last two weeks of the study when the patients could adjust the dose, patients treated with PEG used fewer sachets daily compared to those in the lactulose group; 1.6 vs 2.1, respectively. Only one study has compared PEG 3350 + E with prucalopride in functional constipation, the results of which favored PEG. Nearly 67% of patients treated with PEG improved by the fourth week of the study; they also strained less while passing stools and had less sensation of incomplete evacuation. Similarly, in patients treated with psyllium, the increase in mean weakly defecation rate was considerably lower compared to PEG in the first week of treatment; 1.33 to 5.33 vs 1.18 to 7.95). And after treatment for 2 weeks, 87.3% of patients on PEG + E normalized their defecations vs 66.7% of patients on psyllium. 

There were 28 articles on use of PEG to manage functional constipation in children; these included 17 clinical trials, six observational studies, four prospective studies, two retrospective studies, two reviews and three meta-analyses. The clinical trials compared PEG with placebo, lactulose and showed increase in the number of bowel movements, better stool consistency and less need of rescue treatment with PEG. In another trial vs paraffin oil, improvement in stool frequency was seen with PEG; however, adverse effects were more common in paraffin oil-treated patients. PEG and milk of magnesia had comparable safety and efficacy, but PEG acceptance was much better.

Six trials on the use of PEG in fecal impaction were assessed: three clinical trials, three observational studies, one prospective and two retrospective studies, which have demonstrated the beneficial effect of PEG in fecal impaction.

It was concluded that PEG is a first-line drug for the treatment of functional constipation, in adults as well as in children. It is also effective in relieving fecal impaction. PEG was superior to lactulose, another commonly used laxative. It is safe and has better patient acceptance and tolerability. Comparison of PEG with PEG+E found both formulations to be equally effective, safe and well tolerated and that patients could change from one preparation to the other without loss of efficacy. The recommended doses are 6-12 g/day of PEG + E and 10-20 g/day of PEG in adults, while in children, the recommended doses are around 0.5-0.7 g/kg/day.

Mínguez M, et al. Rev ESPEnferm Dig. 2016 Dec; 108(12):790-806.