Pharmacological Rectal Stimulants

Pharmacological rectal stimulants (suppositories and enemas) are a common component of a successful bowel management program, used by up to 60% of individuals with UMN bowel dysfunction (Coggrave et al. 2009). The two most commonly used are the glycerin suppository, which provides a mild local stimulus and lubrication, and the bisacodyl (dulcolax) suppository, which provides a dose of stimulant laxative directly to the colonic mucosa producing peristalsis throughout the colon. Other options include sodium hydrogen carbonate suppositories, sodium citrate and glycerol micro-enema and docusate sodium micro-enema.


Pharmacological rectal agents (suppositories or enemas) are commonly used by individuals with SCI to stimulate reflex evacuation at the time chosen for bowel care. They are an essential element of a bowel program for many individuals with upper motor neuron bowel though there is little evidence to support most of the suppositories and enemas used. However, the effectiveness of the hydrogenated vegetable oil-based bisacodyl suppositories compared to the polyethylene glycol-based suppositories has been examined. The total bowel care time with the polyethylene glycol-based suppository is significantly less (Stiens et al. 1998Frisbie 1997Dunn & Galka 1994) compared to hydrogenated vegetable oil based suppository. House and Stiens (1997) compared the effectiveness of hydrogenated vegetable-based, polyethylene glycol-based and docusate glycerin (mini-enema) in subjects with upper motor neuron lesions. Results showed a significant decrease in bowel care time using the polyethylene glycol-based suppository and the mini-enema as compared with the hydrogenated vegetable oil-based suppositories. Amir et al. (1998) found in a cohort of seven individuals with SCI that docusate sodium mini enema scored best in neurogenic bowel symptom reduction followed by, in descending order of efficacy, mineral oil enema, bisacodyl suppositories and glycerin suppositories.


There is level 1b evidence (from 1 RCT: House & Stiens 1997) to support polyethylene glycol-based suppositories for bowel management. There is a clinically significant decrease in the amount of nursing time for persons requiring assistance and less time performing bowel care for the independent individual.

Author Year; Country


Research Design

Total Sample Size

Methods Outcome
House & Stiens 1997; USA


PEDro = 7


Population: 9 participants with cervical injuries, 6 with thoracic injuries (11 complete, 4 incomplete); Age range: 26-61; Duration of injury: 3 months to 45 yrs

Treatment: At each regularly scheduled bowel care session, insertion of either a 10 mg hydrogenated vegetable-oil base (HVB) or 10 mg polyethylene glycol base (PGB) suppository. Additionally, 10 participants received 3 TVC (polyethylene glycol-based, glycerine, docusate sodium mini-enemas).

Outcome Measures: time to flatus, flatus to stool flow, defecation period, time to transfer cystometrogram, intracolonic pressure, colonic motor and myoelectrical activity 

  1. Mean time to flatus (min): PGB (15) significantly less time than HVB (32)
  2. Mean time from flatus to stool flow (min): No significant differences. HVB=6.7, PGB=5.5, TVC=3.9.
  3. Defecation Period (mean in min): PGB (20) significantly less time than HVB (36). TVC=17
  4. Total time for bowel program (mean in min): PGB suppositories (43) significantly decreased bowel care time compared to HVB (74.5). TVC=37.
Amir et al. 1998;


Prospective Cohort


Population: Level of injury: C4-T12, 6 participants with tetraplegia, 1 subject with paraplegia; Age range: 21-76yrs; Duration of injury range: 2-25yrs

Treatment: Each subject was studied after receiving one week of therapy with one of the following four modalities: 1) two bisacodyl suppositories, 2) two glycerin suppositories, 3) one mineral oil enema and 4) one docusate sodium mini enema (Theravac SB) daily.

Outcome Measures: total colonic and segmental colonic transit times

  1. Total colonic transit time (CTT) was significantly reduced with docusate sodium mini-enemas. Mean total CTT was 32.0, 34.5, 47.6 and 48.0 hrs with docusate sodium, mineral oil enema, bisacodyl suppositories and glycerin suppositories respectively.
  2. There was no significant difference in total colonic transit times between docusate sodium and mineral oil enema, and both produced significantly shorter transit times compared to bisacodyl or glycerin suppositories.
  3. Bowel evacuation time was least for docusate sodium mini-enemas (31.5 min). Mean evacuation time was 46.5, 57.6, and 63.5 min after mineral oil, glycerin and bisacodyl suppositories, respectively.
  4. In terms of difficulty with evacuation, docusate sodium enema scored best in symptom reduction followed by, in descending order of efficacy, mineral oil enema, bisacodyl suppositories and glycerin suppositories.
Stiens et al. 1998;


Prospective controlled trial


Population: Level of injury: C3-L1 (4 incomplete, 10 with complete); All males; Age: mean 53.4yrs: Duration of injury: mean 18.3yrs

Treatment: PGB vs. HVB bisacodyl suppositories at initiation of side-lying bowel care

Outcome Measures: Time to flatus, flatus to stool flow, defecation period, clean up, total bowel care time

  1. Time to flatus: HVB=31 min is significantly different from PGB=12 min
  2. Defecation period: HVB=58 min is significantly different from PGB=32 min; Total bowel care time is significantly different for: HVB=102 min, PBG=51.2 min (p<0.0005)2.    The numbers of digital stimulations required for the bowel care sessions was not significantly different from HVG and PGB: HVB=5.0, PGB=3.2
Frisbie 1997;


Prospective controlled trial


Population: Level of injury: T1-7 (15 cervical, 4 thoracic); Age: mean (range) 64 (41-81)yrs; Duration of injury: mean (range) 19 (3-51)yrs.

Treatment: A PGB vs HVB bisacodyl suppository

Outcome Measures: Average time for complete bowel evacuation

  1. All patients experienced a shortening of bowel care time with PGB. Average time for bowel evacuation was 2.4 hours (range 1.0-4.5 hours) with HVB and 1.1 hours (range 0.3 to 1.8 hours) with PGB
Dunn & Galka 1994; USA

Case Series


Population: Level of injury: C5-L1, (5 tetraplegics, 9 paraplegics); Age: range 27-67yrs; Duration of injury: range 2-38yrs

Treatment: Phase 1: bisacodyl suppositories for five bowel programs for baseline data. Phase 2: docusate sodium mini enema (Theravac SB) for the next five bowel programs. Phase 3: bisacodyl for five more bowel programs

Outcome Measures: Self-reported diary including time of insertion of the rectal medication; time of first evacuation; time required to complete the first evacuation; other interventions used; bowel problems between bowel programs

  1. 10 participants complete all treatment phases.
  2. Of these 10 participants, the mean evacuation time was significantly reduced with Theravac SB (phase 2) compared to the mean times with both the bisacodyl interventions (phase 1 and 3)
  3. No significant difference in evacuation time between the first (phase 1) and second (phase 3) bisacodyl interventions.