ABSTRACT: BACKGROUND: Stronger prokinetic agents which specifically enhance transit in different parts of the gut are required. R093877 is a novel 5-HT4 agonist prokinetic compound which is chemically related to cisapride but believed to have greater effect on colonic activity. AIMS: To evaluate the effects of R093877 on bowel function, upper and lower gut transit, visceral sensitivity, and sphincter function in healthy volunteers in a double blind, placebo controlled, crossover study. METHODS: The study consisted of five consecutive one week periods: no drug treatment; active drug treatment with either 1 or 2 mg daily or placebo; washout; active drug or placebo; no treatment. Seventeen male subjects maintained a detailed dairy of bowel function for the entire study. Orocaecal transit (breath hydrogen), whole gut transit (radio-opaque markers), and anorectal function were assessed at the end of each of the two treatment periods. Blood testing was performed to confirm compliance and for safety analysis. RESULTS: One subject withdrew from the study due to side effects while on placebo. Eight subjects completed the study on 1 mg and a further eight on 2 mg. Blood testing showed non-compliance in one subject on the 2 mg dose, and he was excluded from analysis of all diary and physiological data. Treatment increased the number of stools per week (placebo versus 1 mg, 7.8 versus 13.6, p = 0.003; placebo versus 2 mg, 8.9 versus 11.3, p = 0.15) and the percentage of loose or watery stools (24.2% versus 61.5%, p < 0.04; 9.9% versus 40.0%, p < 0.02). Stool frequency and consistency reverted to normal immediately after treatment. Treatment shortened orocaecal and whole gut transit in all subjects on both doses. Treatment accelerated orocaecal (76 versus 51 minutes, p = 0.007; 63 versus 47 minutes, p = 0.07) and whole gut (38.2 versus 27.0 hours, p = 0.05; 44.8 versus 24.0 hours, p < 0.04) transit, and decreased the number of retained markers ingested 36 hours previously (4.8 versus 1.8, p = 0.016; 7.0 versus 4.3, p = 0.033). Gut sensitivity to distension and electrical stimulation, and anal manometry, were unchanged. Transient headache occurred in seven subjects on R093877 and one subject had mild elevation of liver aminotransferases which resolved on drug cessation. CONCLUSIONS: R093877 is well tolerated by healthy subjects and has a marked and consistent effect on stool frequency and consistency, and upper gut and colonic transit. It does not affect visceral sensitivity or sphincter function. It holds promise for patients with large bowel symptoms or slow gut transit.
