Duration of Bisacodyl Suppository in the Colon
Bisacodyl suppositories are rapidly absorbed and metabolized in the colon, producing a bowel movement within 15 minutes to 1 hour, after which the medication has completed its local action and is no longer present in meaningful concentrations. 1
Mechanism and Timing of Action
- Bisacodyl suppositories typically work within 30-60 minutes after insertion, which is when the active metabolite exerts its peak effect on colonic tissue 2, 3
- The FDA labeling specifies that rectal bisacodyl generally produces a bowel movement in 15 minutes to 1 hour 1
- Once bisacodyl is inserted rectally, it must be converted to its active metabolite (BHPM) in the gut, which then stimulates colonic peristalsis and secretion locally 2
What Happens After the Bowel Movement
- The medication does not "stay" in the colon after producing its effect - bisacodyl acts locally on the colonic mucosa to trigger high-amplitude propagated contractions (the manometric equivalent of mass movements) 4
- Research demonstrates that bisacodyl infusion into the colon produces motor responses within approximately 13 minutes, followed by defecation within about 18.5 minutes in 75% of patients 4
- After the bowel movement occurs, the medication and its metabolites are expelled along with stool, and any residual drug is rapidly absorbed or metabolized 5
Clinical Context
- Bisacodyl's effect is time-limited and does not persist beyond the immediate bowel evacuation - this is why it's used for acute relief rather than sustained action 3
- The drug acts by directly enhancing motility, reducing transit time, and increasing water content of stool in the large bowel 5
- For colonoscopy preparation, when bisacodyl is used as an adjunct (10 mg on each of the 2 nights before colonoscopy), each dose produces its effect and is cleared before the next dose 6