Fybogel Clinical Trials

1. Mebeverine was included in a relatively recent review of smooth muscle relaxants assessing their efficacy in relieving IBS symptoms:

Meta-analysis of smooth muscle relaxants in the treatment of irritable bowel syndrome.

Alimentary Pharmacology & Therapeutics. 15(3):355-361, March 2001. Poynard, T.; Regimbeau, C.; Benhamou, Y.

Abstract:
Aim: To update previous overviews of placebo-controlled double-blind trials assessing the efficacy and tolerance of smooth muscle relaxants in irritable bowel syndrome.

Methods and trials: A total of 23 randomized clinical trials were selected for meta-analyses of their efficacy and tolerance. Six drugs were analysed: cimetropium bromide (five trials), hyoscine butyl bromide (three trials), mebeverine (five trials), otilium bromide (four trials), pinaverium bromide (two trials) and trimebutine (four trials). The total number of patients included was 1888, of which 945 received an active drug and 943 a placebo.

Results: The mean percentage of patients with global improvement was 38% in the placebo group (n =925) and 56% in the myorelaxant group (n =927), in favour of myorelaxants with a mean odds ratio of 2.13, P < 0.001 (95% CI: 1.77-2.58) and a mean risk difference of 22%P < 0.001 (95% CI: 13-32%). The percentage of patients with pain improvement was 41% in the placebo group (n =568) and 53% in the myorelaxant group (n =567): odds ratio 1.65, P < 0.001 (95% CI: 1.30-2.10) and risk difference 18%, P < 0.001 (95% CI: 7-28%). There was no significant difference for adverse events.

Conclusion: Myorelaxants are superior to placebo in the management of irritable bowel syndrome.

2. Review: Soluble Fibre improves overall symptoms and constipation but not abdominal pain in irritable bowel syndrome

Evid. Based Med. 2004;9;172- doi:10.1136/ebm.9.6.172
G Richard Locke, III

Conventional wisdom is difficult to change, especially when it involves advice that is simple and safe. Many practitioners recommend fibre for the treatment of IBS. The thinking is that fibre can have a laxative effect when people have constipation as well as a stool forming effect when people have diarrhoea. Thus, fibre has been thought to be a reasonable treatment option in IBS. What is the evidence that fibre is helpful? In the systematic review by Bijkerk et al, a total of 17 studies involving 1363 patients were analysed. When all 17 studies were pooled, a beneficial effect of fibre was identified for global symptom improvement. However, when the data were evaluated for soluble and insoluble fibre separately, the effect on overall symptoms was positive for soluble but not insoluble fibre. These studies were conducted between 1979 and 1999 and likely used varying definitions of IBS. Only recently have standardised definitions of IBS been used in clinical trials. Recent studies have often separated patients with diarrhoea predominant IBS from patients with constipation predominant IBS. Specific treatments have differential effects on IBS subtypes. None ofthe studies in this systematic review evaluated the IBS subtypes. Conceivably, dietary fibre might be more helpful in constipation predominant IBS as the studies suggest improvement in the symptom of constipation. None of the studies were conducted in primary care practices. Often the advice related to fibre is offered at the initial encounter. The lack of effect may reflect a referral bias; that is, people who respond well to fibre in a primary care setting are not likely to be referred and, thus, not likely to be recruited into specialty clinic based clinical trials. The authors appropriately highlight the need for trials in primary care. Among the studies of soluble fibre, 7 of 9 were of ispaghula. Thus, only single small studies have been done using the other commonly prescribed forms of soluble fibre. Again, this argues for the need of further research. Finally, the overall effect was relatively small. In part, this is due to the high levels of improvement in the control groups. Thus, the number needed to treat for an effect on global IBS symptom improvement with soluble fibre was 5. What’s the bottom line? Conventional wisdom is partially correct. Soluble fibre in the form of ispaghula appears effective for IBS overall. Any other conclusions related to fibre are based on very little evidence.

G Richard Locke III, MD
Mayo Clinic College of Medicine, Rochester, Minnesota, USA