A phase III trial was conducted to compare the efficacy and safety of polyethylene glycol 3350 plus electrolytes (PEG3350 + E) with placebo for the treatment of Japanese patients with chronic constipation as well as to examine its safety and efficacy over a long period of time. The study was designed as a 2-week, randomized, double-blind, placebo-controlled trial (confirmatory phase) with a 52-week open-label extension (extension phase). Patients with organic constipation or those in whom constipation was caused by drugs or diseases such as hypothyroidism or Parkinson’s disease were not included in the trial.

In the confirmatory phase, patients were treated daily with either 2 sachets of PEG3350 + E or placebo. Two sachets were added every day, up to a maximum of 6 sachets (41.1 g/day), till the stool consistency became normal corresponding to types 3, 4 and 5 on the Bristol Stool form scale (BSFS). The dose was then adjusted according to the stool form.

In the confirmatory phase, compared to placebo group, the frequency of spontaneous bowel movements (SBMs) increased right from the first week of treatment with PEG3350 as did the stool consistency, which was maintained at the same level as type 4 stool defined in the BSFS all through the study. The extension phase of the trial showed that PEG3350 + E was well tolerated. Gastrointestinal disorders such as abdominal pain (4.5%), diarrhea (3.8%), nausea (3.2%) and abdominal distension (2.6%) were observed. These adverse drug reactions were mild in severity. The improvement in the bowel function was sustained for the entire duration of the extension phase. Only 5% patients in the PEG3350 + E group needed rescue medication versus 15% in the placebo group.

The study concluded that PEG3350 + E is a safe and effective treatment for patients with chronic constipation, not only in the short term but also as long-term treatment. PEG3350 + E was also well-tolerated in the long-term treatment of chronic constipation. 

Nakajima A, et al. J Gastroenterol. 2019 Sep;54(9):792-803.