Irritable Bowel Syndrome Message Boards | An over-the-counter drug for constipation offers superior symptom relief compared with a commonly used prescription agent

By Charles Bankhead, Staff Writer, MedPage Today

Published: July 08, 2010

Reviewed by Zalman S. Agus, MD; Emeritus Professor
University of Pennsylvania School of Medicine and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner

Nonprescription treatment for chronic constipation, polyethylene glycol, appears superior to commonly used prescription drug lactulose.

An over-the-counter drug for constipation offers superior symptom relief compared with a commonly used prescription agent, results of a systematic review suggest.

Polyethylene glycol (brand name Miralax) led to greater improvement in stool frequency and form, relief of abdominal pain, and need for additional treatments as compared with lactulose (brand names Enulose, Generlac, Kristalose, Chronulac, Cephulac, Constilac, Cholac, Duphalac, Constulose, Evalose, Heptalac), according to combined data from 10 randomized clinical trials involving more than 850 adults and children.

With the exception of relief of abdominal pain, PEG demonstrated superiority in children and adults alike, authors of the review reported in the Cochrane Database of Systematic Reviews.

"We conclude that polyethylene glycol should be used in preference to lactulose in the treatment of chronic constipation," Heather Lee-Robichaud, MD, of Northern General Hospital in Sheffield, England, and co-authors wrote.

Chronic constipation affects a substantial proportion of adults and children. Owing to the subjective nature of symptoms and lack of consensus about a clinical definition, prevalence estimates range from 2% to 35%, the authors noted.

Numerous factors have been cited as possible causes of chronic constipation, but the etiology remains largely unknown, they continued. Treatment recommendations usually begin with hygienic measures, such as increased physical activity and hydration and dietary modification. If these steps fail to relieve symptoms, patients usually turn to suppositories, laxatives, enemas, and manual evacuation.

Pharmacologic therapy for chronic constipation spans a wide range of prescription and nonprescription agents, which generally have a modest impact on symptoms, owing to the poor understanding of the pathophysiology of chronic constipation, the authors wrote. A group of drugs known collectively as "laxatives" constitute the most common type of drug therapy.

The laxative class includes PEG and lactulose, both of which are osmotic laxatives that work by increasing the amount of water in the large bowel. More than a dozen randomized clinical trials have compared the two agents, but their relative efficacy and cost-effectiveness remain unclear. To address that uncertainty, Lee-Robichaud and co-authors performed a systematic review and meta-analysis of the clinical trials.

A literature search identified 16 randomized comparisons of PEG and lactulose, 10 of which the authors included in their analysis. The trials included children and adults who had chronic constipation by Rome III diagnostic criteria (Gastroenterology 2006; 130: 1480-1491) or fecal impaction. The primary outcome of the analysis was change in stool frequency. Secondary outcomes included need for additional therapies (such as enemas or other types of laxatives), global symptom improvement, and relief of abdominal pain.

The 10 trials included a total of 868 patients, 322 adults and 546 children.

Five trials involving 407 patients compared PEG and lactulose effects on stool frequency. All five studies favored PEG, resulting in a mean treatment effect of 0.65 (0.15 to 1.15) versus lactulose. Separate analyses of children and adults also showed a consistent advantage for PEG, with mean treatment effects of 1.57 for children and 0.28 for adults.

Two trials examined stool form, and both demonstrated superiority for PEG, resulting in a mean treatment effect of 0.89 (0.43 to 1.35). Results were similar for children and adults. The three trials that assessed relief of abdominal pain showed a mean treatment effect of 2.09 in favor of PEG (1.26 to 3.44). The three trials that assessed need for additional products yielded a mean treatment effect difference of 4.00 in favor of PEG (2.01 to 7.95).

Co-author Richard L. Nelson, MD, also of Northern General Hospital, cautioned that drug treatment should be reserved for patients with chronic constipation, not for those who have only occasional episodes. Moreover, the decision to use drug therapy is complicated by the subjective nature of patient symptoms and complaints.

"The border between normal variation and a symptom of disease can be very hazy," Nelson said in a statement.

The authors reported no disclosures.

Primary source: Chochrane Database of Systematic Reviews
Source reference:
Lee-Robichaud H, et al "Lactulose versus polyethylene glycol for chronic constipation" Cochrane Database Syst Rev 2010; DOI: 10.1002/14651858.CD007570.pub2.

http://www.medpagetoday.com/Gastroenterology/GeneralGastroenterology/21063

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Heather is the Administrator of the IBS Message Boards. She is the author of Eating for IBS and The First Year: IBS, and the CEO of Heather's Tummy Care. Join her IBS Newsletter. Meet Heather on Facebook!

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