It is unclear how
polyethylene glycol (PEG) laxatives compare with other classes of
laxative in terms of efficacy. To assess efficacy of PEG vs. placebo and active comparators in adults with non-organic
constipation. Text Word searches were carried out on MEDLINE, EMBASE, CINAHL, Cochrane Central Register of Clinical Trials and Google Scholar databases covering the period January 1970 to October 2009. Search terms were (
constipation) AND (randomised OR randomized) AND (PEG OR
polyethylene OR
macrogol OR movicol OR idrolax OR
miralax OR transipeg OR forlax OR
colyte OR
golytely OR
isocolan OR
nulytely) NOT colonoscopy. Only published randomised controlled trials, with a parallel-group or cross-over design, comparing oral PEG with placebo or a comparator
laxative in adults with a history of non-organic
constipation, were included. The frequency of defaecation in each arm, on completion of the protocol-defined
treatment duration was extracted. All pooled analyses were based on random effect models. Of the 20 qualifying studies, 10 were vs. placebo, seven were vs.
lactulose, and four were vs. other agents. One study compared PEG, placebo and
lactulose. PEG treatment resulted in a highly significant increase in defaecations/week over placebo (all studies: additional 1.98 stools/week; p = 0.0003, high-quality studies: additional 2.34 stools/week; p = 0.0001) and over
lactulose (all studies: additional 1 stool/week; p = 0.0017, high-quality studies: additional 1.65 stools/week; p = 0.021). This meta analysis is the only quantitative statistical analysis to have been published in the field. PEG was found to be a more effective
laxative than
lactulose in adult patients with
constipation.