The constipating effect of diphenoxylate (Retardinr) in ulcerative colitis. A double-blind controlled trial

A double-blind study of 20 patients with ulcerative colitis during treatment with diphenoxylate 5 mg three times daily and placebo is reported. There were two treatment periods of 14 days each, with cross-over technique and randomized sequence. Test variable for constipating effect was the mean number of defaecations per day. The criterion for inclusion of patients was the presence of 4 or more daily bowel movements; 2 patients did not complete the investigation. Significant difference (p less than 0.01) in constipating effect between diphenoxylase and placebo was demonstrated both during a period of 12 days and a period of 6 days (Tables II and III). The average number of bowel movements were reduced by 0.7 and 1.3 per day respectively. Side-effects during treatment with diphenoxylate were seen in 53% (Table III) with significant difference against placebo (p less than 0.05). On the basis of the small absolute reduction of defaecation frequency side-effects, it is concluded that diphenoxylate has no place in the routine treatment of ulcerative colitis.