This study is being done to evaluate the effects of lubiprostone, a drug approved and used for constipation, on pattern of contractions of the colon and the colon's sensitivity to distension.
This was a trial of healthy adults to compare the effects of oral lubiprostone, 24 microgram per day and placebo for three days, on sensation and contractions of the colon using validated methods. On days 1 and 2, participants took the study medication with their breakfast and recorded the time. On day 2 starting at 4:00 pm, participants started a polyethylene glycol-based bowel preparation to cleanse the colon. After overnight bowl preparation, participants reported fasting to the study center at 7:00 am on day 3. Colonic sensorimotor functions were assessed by an endoscopically placed barostat-manometric assembly. After 30 minutes of rest following tube placement, fasting colonic tone, colonic compliance and colonic sensation were tested. The last dose of medication was ingested and 1 hour later the same colonic functions, as well as colonic response to a standardized meal of a 1,000-kilocalorie chocolate milkshake were assessed. The participant was able to leave the study center in the afternoon, after a meal had been ingested (if desired). Details on colonic tube placement: A flexible sigmoidoscopy was performed to evaluate the left side of the colon and to place a Teflon-coated guide wire beyond the splenic flexure. The colon was deflated as the sigmoidoscope was removed and a barostat catheter (constructed at Mayo Clinic, Rochester, MN) with six manometric point sensors and a polyethylene balloon was introduced into the colon over the guide wire. The barostat catheter was positioned in the mid-descending or upper sigmoid colon with the aid of fluoroscopy. The final position of the barostatically controlled balloon was confirmed by fluoroscopy. After the colonic tube placement, participants rested for 30 min. The catheter was connected to a rigid piston barostat machine. After transient inflation of the barostat bag to a volume of 75 ml to ensure it was unfolded, it was deflated. Thereafter, it was inflated in 2 mm Hg increments to baseline operating pressure, which was defined as 2 mm Hg above the minimal distension pressure at which respiratory excursions were clearly recorded by the barostat tracing.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
60
Lubiprostone 24 micrograms, one dose daily for three days in 30 subjects
Placebo medication given for three days
Polyethylene glycol-based bowel preparation
Mayo Clinic
Rochester, Minnesota, United States
Colonic Compliance
Colonic compliance is a measure of the "stiffness" of the colon, that is, what pressure was needed to reach half the maximum volume of the colon. After the barostat catheter was inserted in the colon, the catheter was connected to a barostat machine. After an initial conditioning distension to 20 mm Hg, colonic compliance was measured by step-wise inflation with increments of 4 mm Hg up to 64 mm Hg. Colonic compliance was analyzed by a validated linear interpolation method. The pressure at half maximum volume serves as a summary of colonic compliance.
Time frame: 1 hour after third dose of lubiprostone or placebo, on Day 3
Fasting Colonic Tone
Colonic tone is a measurement of the volume of the colon. Colonic tone was assessed by noting the changes in the balloon volume in the presence of a constant operating pressure in the balloon (in the barostat-manometric assembly placed in the colon).
Time frame: 30 minutes after the colonic tube placement, on Day 3
Postprandial Colonic Tone
Colonic tone was assessed by noting the changes in the balloon volume in the presence of a constant operating pressure in the balloon (in the barostat-manometric assembly placed in the colon).
Time frame: 30 minutes after standard meal, on Day 3
Pain Sensation Ratings in Response to Colonic Distension at 32 mm HG Above Baseline Operating Pressure
Pain was measured by a 100 mm long Visual Analog Scale (VAS). The VAS does not have any pre-set marks between the extremes of 0 for no pain and 100 mm for extreme pain. The investigator measures the mark made by the participant in mm and records this for the value of pain.
Time frame: approximately 1 hour after colonic tube placement, on Day 3
Gas Sensation Ratings in Response to Colonic Distensions at 32 mm Hg Above Baseline Operating Pressure
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Gas sensation was measured by a 100 mm long Visual Analog Scale (VAS). The VAS does not have any pre-set marks between the extremes of 0 for no gas sensation and 100 mm for extreme gas sensation. The investigator measures the mark made by the participant in mm and records this for the value of gas sensation.
Time frame: approximately 1 hour after colonic tube placement, on Day 3
Median Pressure When First Sensation Was Reported by 50% of Participants
The sensory threshold for first sensation was measured by stepwise inflation in increments of 4 mm Hg at 60 second intervals up to a maximum pressure of 64 mmg Hg. During this assessment participants were asked to report when they had the first sensation. The investigator recorded the threshold pressure at which the participants reported this sensation.
Time frame: approximately 45 min after colonic tube placement, on Day 3
Median Pressure When Gas Sensation Was First Reported by 50% of Participants
The sensory threshold for first perception of gas was measured by stepwise inflation in increments of 4 mm Hg at 60 second intervals up to a maximum pressure of 64 mmg Hg. During this assessment participants were asked to report when they had the first perception of gas. The investigator recorded the threshold pressure at which the participants reported this sensation.
Time frame: approximately 45 min after colonic tube placement, on Day 3
Median Pressure When Pain Sensation Was First Reported by 50% of Participants
The sensory threshold for first perception of pain was measured by stepwise inflation in increments of 4 mm Hg at 60 second intervals up to a maximum pressure of 64 mmg Hg. During this assessment participants were asked to report when they had the first perception of pain. The investigator recorded the threshold pressure at which the participants reported this sensation.
Time frame: approximately 45 min after colonic tube placement, on Day 3