A Double-Blind Placebo-Controlled Trial with Loperamide in Irritable Bowel Syndrome

Background: Loperamide has a relaxing effect on localized and segmental large-bowel spasms. On the basis of previously observed effects on pain and stool habits in patients with diarrhoea, the present trial intended to examine the regulating effect in an unselected cohort of patients with the irritable bowel syndrome (IBS). The symptoms in IBS are dependent on variations in motility initiated by different mechanisms. Therefore, when examining the effect of treatment, characterization of the patient material is important. Methods: Ninety patients were included in this prospective double-blind trial comparing loperamide with placebo over 5 weeks. The two groups were characterized and compared with healthy controls (n = 33), matched by age and sex. Demographic, clinical, and biochemical data were recorded. Results: Clinical variables and social and personal relationships were similar for the loperamide group (n = 35), the placebo group (n = 34), the dropouts (n = 21), and the controls. Somatic diseases and mental disturbances were increased in the patients compared with the controls. Throughout the 5 weeks of treatment an improved stool consistency (32%), reduced defecation frequency (36%), and reduced intensity of pain (30%) were found in the loperamide group. An increase in nightly pain was observed in the loperamide group. Conclusions: This trial lends support to a multifactorial aetiology in IBS. Treatment must be individualized with regard to both the effect and the risk of constipation and abdominal pain. The trial shows a benefit of loperamide in an unselected cohort of IBS patients with regard to stool frequency, stool consistency, and the overall pain intensity, but with increased abdominal pain during the night. It should be recommended that the patients take the medication in divided daily doses.