The Effect of Lubiprostone, a Chloride Channel Activator, on Colonic Sensorimotor Functions in Healthy Subjects. A Phase IV, Placebo-Controlled, Parallel Group Study

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.