Commentary

Myth of the Month: Does Colace work?


 

Myth: Docusate is a stool softener and helps with constipation.

A 60-year-old man is injured in a fall and breaks four ribs. He is in severe pain and is prescribed oxycodone and naproxen for pain. What treatment would you prescribe to help decrease problems with constipation?

A. Docusate.

B. Docusate and polyethylene glycol.

C. Psyllium.

D. Polyethylene glycol.

Constipation is extremely common, occurring in up to 20%-25% of the elderly population and 90% of patients treated with opioids. The formal definition of constipation is fewer than three bowel movements per week. Patients are concerned with other symptoms as well, including hard stool consistency and the feeling of incomplete evacuation.

An extremely commonly prescribed medication for patients with symptoms of constipation/hard stool passage is docusate (Colace). This medication is often a part of bowel programs for institutionalized/hospitalized patients, as well as being frequently prescribed when patients are treated with opiates.

Does it work?

Dr. Douglas S. Paauw

Dr. Douglas S. Paauw

Docusate is frequently prescribed as a “stool softener,” but does it increase water content in stool? In a randomized, controlled trial of docusate vs. psyllium, 170 adult patients with chronic constipation received either 5.1 g twice a day of psyllium or 100 mg twice a day of docusate (Aliment Pharmacol Ther. 1998 May;12[5]:491-7).

Psyllium was superior in its effect on stool frequency, stool water content, total stool output, and the combination of several objective measures of constipation. Compared with baseline, psyllium increased stool water content by 2.33%, vs .01% for docusate (P =. 007), and stool weight was increased in the group treated with psyllium, compared with docusate-treated patients (359.9 g/week vs. 271.9 g/week, respectively; P = .005). Docusate does not appear to have any effect on stool water content or amount of stool.

In a study of constipation treatment in patients receiving opioids, Dr. Yoko Tarumi and her colleagues studied 74 patients admitted to hospice units (J Pain Symptom Manage. 2013 Jan;45[1]:2-13). A total of 74 patients were randomized to receive docusate 100 mg twice a day plus senna, or placebo plus senna. Once the study was started, inclusion criteria were broadened to include hospice patients with nonmalignant disease and patients who were not on opioids.

Almost all patients in the study did receive opioids (94% of the docusate patients and 100% of placebo-treated patients). There were no significant between the groups in stool volume, frequency, consistency, or in perceived completeness of evacuation.

In a randomized, controlled study of elderly patients on a medicine ward, 34 patients were randomized to docusate or control (no laxatives)(J Chronic Dis. 1976 Jan;29[1]:59-63). There was no difference in frequency or quality of stools between groups.

A systematic review of the usefulness of docusate in chronically ill patients concluded that the widespread use of docusate for the treatment of constipation in palliative-care patients is based on inadequate experimental evidence (J Pain Symptom Manage. 2000 Feb;19[2]:130-6).

The Canadian Agency for Drugs and Technologies in Health concluded “the available evidence suggests that docusate is no more effective than placebo in the prevention or management of constipation” (Dioctyl sulfosuccinate or docusate [calcium or sodium] for the prevention or management of constipation: a review of the clinical effectiveness. Canadian Agency for Drugs and Technologies in Health; 2014 Jun 26).

Dr. Davendra Ramkumar and his colleagues published a systematic review of drug trials for the treatment of constipation in 2005 (Am J Gastroenterol. 2005 Apr;100[4]:936-71). Only polyethylene glycol and tegaserod received grade A evidence for published trials. Psyllium and lactulose received grade B evidence. Docusate received a level 3, grade C for evidence (poor quality evidence, poor evidence to support a recommendation for or against the use of the modality).

I have been surprised at how docusate has been the most commonly prescribed laxative agent. Polyethylene glycol or psyllium are better evidence-based options. Docusate is often prescribed as a stool softener, and it has even less evidence that it softens stool than its poor evidence as a laxative.

Acknowledgments

My thanks to the late Dr. David Saunders for teaching me 30 years ago that docusate was not a helpful option for the management of constipation, and to Sarah Steinkruger for doing much of the research that was used in this column.

Dr. Paauw is professor of medicine in the division of general internal medicine at the University of Washington, Seattle, and he serves as third-year medical student clerkship director at the University of Washington. Contact Dr. Paauw at dpaauw@uw.edu.

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