The present study compared the safety and efficacy of PEG laxative contrasted with placebo over a 6-month treatment period in chronic constipation patients.

It randomized the patients with chronic constipation to receive PEG laxative as a single daily dose of 17 g or a placebo for six months. The study confirmed baseline constipation status during a 14-day observation period. It defined treatment success as relief of modified ROME criteria for constipation for 50% or more of their treatment weeks. 

An Interactive Voice Response System (IVRS) was employed to record daily bowel movement experiences and study efficacy and safety information. 

The study observed-

• Enrollment of 304 patients. 
• 52.0% of PEG and 11% of placebo participants demonstrated successful treatment according to the primary efficacy variable. 
• A subgroup of 75 elderly subjects showed similar efficacy. 
• 61% of PEG treatment weeks and 22% of the placebo weeks were successful, based on the primary efficacy definition.
• No significant differences in laboratory findings or adverse events except for the gastrointestinal category (diarrhea, flatulence, and nausea) were frequent with PEG, although not individually significant compared with placebo. 
• Similar results after adjusting for gender, race, or age.

This study demonstrates the safety and efficacy of PEG laxative for use in patients with chronic constipation for a prolonged duration, i.e., six months.

Dipalma JA, Cleveland MV, McGowan J, Herrera JL. A randomized, multicenter, placebo-controlled trial of polyethylene glycol laxative for chronic treatment of chronic constipation. Am J Gastroenterol. 2007 Jul;102(7):1436-41. doi: 10.1111/j.1572-0241.2007.01199.x. Epub 2007 Mar 31. PMID: 17403074.