Daily Bisacodyl Effective for Chronic Constipation

The over-the-counter laxative bisacodyl has been available for decades. Intestinal enzymes convert this agent into an active metabolite, bis-(p-hydroxyphenyl)-pyridyl-2-methane (BHPM). BHPM stimulates fluid secretion and also has a direct prokinetic effect. Gastroenterologists often recommend bisacodyl — but primarily for short-term use, out of concern that patients will develop tolerance and then require either higher doses or a different laxative. Whether it should be used in chronic constipation remains uncertain: Few data are available from controlled trials.

Investigators recently addressed this issue in a manufacturer-sponsored, multicenter, double-blind trial conducted in the U.K. among adults who fulfilled Rome III criteria for chronic constipation. During a 2-week baseline period, all had fewer than three complete spontaneous bowel movements (CSBMs) per week on average and at least one additional symptom — straining, incomplete evacuation, or lumpy or hard stools — more than 25% of the time. A total of 368 participants (75% women; mean age, 55) were randomized in a 2:1 ratio to receive oral bisacodyl (10 mg daily) or placebo for 4 weeks.

The mean number of CSBMs per week during treatment increased from a baseline of 1.1 in both groups to 5.2 in the bisacodyl group and 1.9 in the placebo group. In each group, the mean number of CSBMs per week exceeded baseline levels throughout treatment, peaking during week 1, and then declining slightly and remaining fairly stable for the next 3 weeks. Constipation-related quality-of-life scores improved significantly more in the bisacodyl group than in the placebo group. Adverse events (generally diarrhea and abdominal pain, and during the first treatment week) were nearly twice as common in the bisacodyl group. Discontinuation was also more common in the bisacodyl group (17.8% vs. 5.0%).