Polyethylene glycol versus vegetable oil based bisacodyl suppositories to initiate side-lying bowel care: A clinical trial in persons with spinal cord injury;

Steven J. Stiens , William Luttrel2 and Joseph L Binard3. VA Puget Sound Health Care System, Department of Rehabilitation Medicine, University of Washington. Seattle. Washington; ‘Veterans Administration Medical Center. Spinal Cord Injury Unit, Palo Alto. California; 3Veterans Administration Medical Center, Departments of Urology & Family Medicine, University of South Florida. Tampa, Florida. USA

Injuries to the spinal cord (SCI) that result in upper motor neuron damage frequently produce neurogenic bowel dysfunction. The upper motor neuron bowel is characterized by fecal retention and uniformly requires a scheduled evacuation plan to avoid impaction and incontinence. These bowel programs (BPs) remain time-consuming processes that may be detrimental to quality of life.1 Bowel regimens may last longer than 3 hours and still produce insufficient results.2 Consequently, despite tedious and exacting BP regimens, serious problems with bowel evacuation are still reported from as many as 20% of people with SCI.3

Suppositories consisting of active laxative ingredients dispersed in a base substance are commonly used in a BP. Bisacodyl is the most commonly used active ingredient in rectal chemical stimulant preparations for defecation. This compound, a diphenylmethane derivative (bis (p-acetoxy phenyl)-2-pyridymethane) was first introduced for use as a laxative in 1953 because of its structural similarity to phenolphthalein. Acting as a contact laxative, bisacodyl is practically insoluble in water and sparingly soluble in alcohol.

From the Veterans Affairs Medical Center SC! Service and Department of Rehabilitation. University of Washington, Seattle. Supported In pare by Research Enrichment Program for Physiatrists. NIDRR no. H133P10011 Submitted for publication September 2. 1994, Accepted in revised form February 6,1995. No commercial company having a direct financial interest in the results of the research supporting this article has or will confer a beneth upon the authors or upon any organizations with which the authors are associated. Reprint requests to Steven A. Stiens. MD, University of Washington, Department of Rehabilitation. Mail Location RJ-30, Health Sciences Building 8B938. 1959 NE Pacific, Seattle, WA 98195. © 1995 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation 003-9993/95/76O7-322 $3.00/0

Administered rectally in a water suspension, bisacodyl acts within 3 minutes to produce suppression of rhythmic stationary spike wave activity and increases spasmodic propulsive peristaltic spike activity,4 Bisacodyl is available in many rectal preparations including suppositories, enemas, mini-enemas, and solutions.5 Typically. 10-mg suppositories are used because of the ease of insertion and retention. The most common suppository preparation includes bisacodyl powder distributed within a hydrogenated vegetable oil base (HVB).5 Bisacodyl suppositories with a vegetable oil base often require a prolonged period to produce defecation and can cause continued mucosal irritation with resultant mucus accidents hours after the BP. Water-miscible suppositories have recently been used. Bisacodyl suppositories made with the polyethylene glycol polymer bases have been anecdotally reported to produce quicker elimination.6

This study was performed to compare BP times using HVB and polyethylene glycol-based bisacodyl (PGB) suppositories. The primary question in clinical practice relates to the effectiveness of a new treatment regimen in a particular patient. The idiographic, single case study method is used here to show a method of monitoring patient progress with changes in response to a pharmacological bowel elimination regimen.7


The subject is a 35-year-old white man with a 10-year history of T2 complete stable paraplegia that resulted from a spinal cord arteriovenous malformation. Physical examina- tion showed moderate scoliosis and decreased abdominal which was first introduced for use as a laxative in 1953 due to its structural similarity to phenolphthalein. Bisacodyl which acts as a contact laxative is practically insoluble in water and sparingly soluble in alcohol. Given rectally in a water suspension it is dispersed along the colonic mucosa. The colonic response can be detected with mucosal electromyography. Bisacodyl then acts within as little as 3 min to suppress rhythmic stationary spike wave activity and increase spasmodic propulsive peristaltic spike activity.9 Thereafter, reflex defecation ensues. Bisacodyl can be administered in many preparations including suppositories, enemas, mini enemas, and solutions.1,10 For independent bowel care after SCI typically, 10 mg suppositories are used due to ease of insertion with dexterity deficits and improved anal retention without voluntary external anal sphincter constriction. The most common suppository preparation includes bisacodyl powder dispersed within a hydrogenated vegetable oil base (HVB).10 Anecdotal reports suggest bisacodyl suppositories with a vegetable oil base often require a prolonged period to produce defecation and can cause continued mucosal irritation with resultant mucus accidents hours after bowel care is completed. As a result, water-miscible suppositories have been introduced. We have evaluated the effect of polyethylene glycol polymer based (PGB) bisacodyl suppositories using a single subject design.11 We found that defecation was initiated more rapidly with a resultant significant shortening of the total bowel care time. This study was carried out to compare the effectiveness of hydrogenated vegetable oil based and polyethylene glycol based bisacodyl suppositories in triggering and producing reflex defecation in a cohort of SCI subjects during bowel care administered within a hospital setting.


Recruitment focused on inpatient SCI persons at the Tampa Veterans Affairs Medical Center SCI unit. Subjects were invited to enter the evaluation if they had been SCI for greater than 1 year, had an upper motor neuron lesion, and used HVB bisacodyl suppositories in a regular, stable bowel care regimen. Subjects were excluded if there was a recent history of constipation, diarrhoea, or medication that could adversely affect bowel function. Baseline demographic information on each subject included: age, years since SCI, SCI level, bulbocavernous reflex, anocutaneous reflex, anal tone, and phasic reflexes of the lower extremities.1

The two types of bisacodyl suppositories used in the study differed only in the base used for dispersion of the active ingredient. The HVB suppositories utilized contained 10 mg bisacodyl USP in a hydrogenated vegetable oil base (UDL Lab, Rockford, USA). The PGB suppositories (Concepts in Confidence, Islandia. NY. USA) contained 10 mg bisacodyl dissolved in a mixed polyethylene glycol polymer base of two molecular weights: E1450 and E400.

Subjects received one l-IVB suppository for six sequential regularly scheduled bowel care procedures followed by one PGB per rectum for the following six BC sessions. Each bowel care procedure was performed by a staff nurse with the consistent technique and data collection.1 All subjects were positioned side-lying with the left side down and knees flexed. At the beginning of each bowel care session, either a PGB or a HVB bisacodyl suppository was inserted and positioned against the mucosal surface of the rectum at a finger length from the anus. The presence or absence of stool in the rectal vault was recorded. The time of insertion was considered time zero and the progress of bowel care was documented with time parameters (Figure l).11

Bowel care events were used to separate the total bowel care time period into discrete intervals recorded in minutes: First flatus (ends the interval from suppository insertion until the first gas is passed), Begin stool flow (marks the beginning of the defecation interval), End stool flow (marks the end of defecation interval), and Wait until transfer (marks the end of the period of waiting after stool flow has ended, the subjective end of the bowel care).1,11 For the purpose of this study bowel care was deemed complete at the end of the perianal clean up (End clean up) after waiting to see that no further stool was expelled. Our subjects had bowel care in bed and did not Events and Intervals of Bowel Care

Figure 1 Bowel care session events separate the total bowel care period into four discrete intervals. Bowel care begins with suppository insertion. First flatus ends the first interval. Time to flatus (suppository insertion until first gas is passed). Begin stool flow ends the second interval termed Flatus to stool flow and begins the Defecation period. End stool flow represents the time when Defecation period has immediately ceased. The time of Transfer off the toilet ends the Wait until transfer period which represent the time spent to insure that the bowel care is over. The time of Transfer off the toilet ends bowel care. If there is no transfer then the end of bowel care is defined as the end of clean up of the perianal area End clean up. The total bowel care time is the period from the suppository insertion until the Transfer off the toilet or end clean up