Single-dose Linaclotide for Capsule Endoscopy Preparation

Video capsule endoscopy is an important modality for detection of lesions in the small intestine. It is particularly helpful in patients with occult sources of gastrointestinal bleeding, suspected Crohn's disease, ulcerative jejunitis, and in cases where a small intestinal neoplasm is suspected. Despite advances in technique and equipment, significant limitations remain in obtaining adequate visualization due to dark bilious fluid that obscures the mucosa. Furthermore, limitations of battery technology mean that in approximately 16.5% of studies the capsule will fail to visualize the entire small bowel. Numerous methods of bowel preparation have been used for capsule endoscopy. To date, all of them are unpleasant/have significant side effects. This is particularly onerous given that the majority has already had a similar but more extensive preparation for colonoscopy. Furthermore, overall efficacy is varied, and the preparation frequently remains suboptimal. The University of Virginia Health System Motility Lab uses a current regimen of 2000 mL of golytely and simethicone, but incomplete and partially occluded portions of the small bowel remain persistent clinical issues. Nearly one in five studies may ultimately have to be repeated as a result.

A recent presentation by Ira J. Schmelkin, M.D. proposed the use of single-dose linaclotide for capsule endoscopy preparation to supplement fasting and clear liquid diet. In an uncontrolled series, he noted a clinically significant improvement in preparation quality and a 20% shorter transit time (compared with published norms) with one higher range dose of linaclotide an hour prior to endoscopy. Linaclotide is guanylate cyclase-C that acts on the luminal surface of the intestinal epithelium thereby stimulating secretion of chloride and bicarbonate into the intestinal lumen, resulting in increased intestinal fluid and increased motility. The increased motility and secretion throughout the gastrointestinal tract make it a potentially useful agent to decrease capsule transit time and decrease the amount of dark small intestine fluid, thereby improving capsule endoscopy yield. Initial reports suggest that linoclotide is generally well tolerated, with the primary side effect of diarrhea. The investigators propose to study the use of a single dose for capsule endoscopy preparation.

The hypothesis is that single-dose linaclotide will lead to significantly decreased transit time and improved small bowel visualization quality when compared to controls using polyethylene glycol and simethicone (standard of care).

The investigators propose to prospectively enroll approximately 30 patients as subjects, who will receive a single dose of 290mcg one hour prior to capsule endoscopy. This was calculated using power calculations from values of the Viazis study, who noted an average transit time of approximately 290 minutes, compared with approximately 190 minutes in the data from Schmelkin. Given the standard deviation of approximately 90 minutes in Viazis, power calculation with an alpha of 0.05 and a beta of 0.80 would require 18 subjects per group. The investigators will target 30 to allow for dropouts and to allow the use of statistics pertaining to large (approximately 30 and up) numbers of subjects.

All adult patients undergoing capsule endoscopy (with the exception of certain criteria, such as severe gastroparesis, pregnancy, non-English speaking, prisoners, those unable to give consent, prior small intestinal resection) will be approached sequentially until completion of the study. These will be matched 1:1 with historic controls selected at random from cases in the prior three years. The same exclusion criteria will be applied to both groups. There will be two primary outcomes: total transit time and rated overall mucosal visualization (categorized as ideal, good, inadequate or poor/needs repetition). Primary analysis will presume no confounding and use a t-test and chi-square, respectively. Should the groups prove significantly different, the investigators also plan to use adjusted analysis. The investigators will plan to collect BMI, history of reflux, age, sex, gastroparesis, diabetes, narcotic use, other conditions e.g. Parkinson's, lupus, scleroderma as these may affect transit time for the historic controls.

Two gastrointestinal fellows or attending level gastroenterologists will perform the scoring of the images recorded during the capsule endoscopy in a blinded manner. Secondarily, the investigators will also look at the percentage of capsule endoscopies detecting a culprit lesion, and the percentage of failed (incomplete) studies.