Kienzle-Horn, S., Vix, J.M., Schuitjt, C., Peil, H., Jordan, C.C., & Kamm, M.A. (2006). Efficacy and safety of bisacodyl in acute treatment of constipation: A double-blind, randomized, placebo-controlled study. Aliment Pharmacology and Therapeutics, 23, 1479–1488.

To determine the effect and safety of oral bisacodyl on stool frequency and consistency.

Patients received bisacodyl 10 mg (two 5-mg tablets) or placebo (two tablets) orally once daily on three successive days following a three-day run-in period. The study had a three-day baseline period and three treatment days. Patients were asked not to drink milk or take antacids at the same time as study medications because they could dissolve the enteric coating. Randomization was 1:1. Unused medication was collected at the end of the treatment period. Primary endpoints during the three-day treatment period were mean number of stools per day and mean stool consistency.

• The study reported on a sample of 54 Caucasian patients with idiopathic constipation, aged 19 to 89 years.
• The bisacodyl group (n = 27) comprised 19 women and 8 men, whereas the placebo group (n = 27) comprised 20 women and 7 men.
• Patients were included in the study if they were aged 18 years or older, had a documented history of constipation well known to the investigator, and were otherwise in good health.
• Patients were excluded if they had constipation associated with drug treatment, organic disease (e.g., tumors), strictures, inflammatory disease, obstructive conditions, other gastrointestinal (GI) disorders, history of GI surgery, or pregnancy.

Eight primary care practices in Germany

This was a phase IV, multicenter, double-blind, randomized, placebo-controlled, parallel group design study.

• Constipation was defined as fewer than three bowel movements per week on average during the past three months, or excessive need for straining, hard stool, low-stool weight, or sensation of incomplete evacuation in more than 25% of evacuations.
• Patients recorded stool frequency and consistency and adverse events in a bowel diary.
• Blood specimens (complete blood counts and chemistries) were obtained.
• Global assessment of efficacy was made by the investigator based on severity of constipation compared with baseline on a four-point Likert-type scale.

• Twenty-seven patients were evaluable in each group for efficacy.
• Two patients were excluded secondary to taking restricted concomitant medications.
• One subject was lost to follow-up before taking study medication.
• Patient demographics were comparable.
• Mean number of stools per day was significantly greater in the bisacodyl group (1.8, SD = 1.5) compared to placebo (0.95, SD = 0.6) over the treatment phase (p = 0.0061).
• Mean stool consistency score improved from hard at baseline for both groups to soft and well formed (2.8, SD = 1.1) during bisacodyl treatment, remaining from moderately hard to hard for placebo (4.2; p < 0.0001).
• In terms of global efficacy assessment, 19 of 27 patients in the bisacodyl group compared to 14 of 27 patients in the placebo group were assessed as significantly or somewhat improved; the finding was not statistically significant (p = 0.423).

Bisacodyl is effective and safe in improving stool frequency and consistency.

• The power analysis needed 28 patients per group, but only 27 patients per group completed the study.
• All patients were Caucasian.
• The sample was predominantly female, which is reflective of a higher proportion of women experiencing constipation in the general population.
• Although adverse events were reported, no evidence suggested patients were specifically asked about abdominal cramping and flatulence, which were listed as objective rather than subjective symptom data by the authors.
• Patients in the study were in good health; therefore, patients with cancer were excluded.