Review: Smooth-muscle relaxants improve symptoms and reduce pain in the irritable bowel syndromePDF
ACP J Club. 2001 Sep-Oct;135:53. doi:10.7326/ACPJC-2001-135-2-053
Poynard T, Regimbeau C, Benhamou Y. Meta-analysis of smooth muscle relaxants in the treatment of irritable bowel syndrome. Aliment Pharmacol Ther. 2001 Feb;15:355-61. [PubMed ID: 11207510] (All 2001 articles were reviewed for relevancy, and abstracts were last revised in 2007.)
In patients with the irritable bowel syndrome (IBS), are smooth-muscle relaxants safe and efficacious for global improvement of symptoms?
Randomized controlled trials were identified by searching MEDLINE with the terms colonic disease, functional, irritable bowel syndrome, and randomized trial; Current Contents; and bibliographies of relevant trials, meta-analyses, and reviews. Drug companies were also contacted.
Trials were selected if they were double-blind studies that compared muscle relaxants with placebo, ≥ 51% of patients had IBS, the drugs studied had myorelaxant properties, and ≥ 1 end point of global assessment of symptoms, abdominal pain, constipation, or abdominal distention was included.
Data were extracted on study quality, patient characteristics and numbers, drug and dosage, treatment duration, and outcomes.
23 trials (1888 patients) met the inclusion criteria. 6 drugs were studied: cimetropium bromide (5 trials), hyoscine butyl bromide (3 trials), mebeverine (5 trials), otilium bromide (4 trials), pinaverium bromide (2 trials), and trimebutine (4 trials). All drugs analyzed together and each drug analyzed separately, except pinaverium alone, showed improvement in global symptom ratings (Table). All drugs combined (and otilium and cimetropium alone) reduced pain (Table). Abdominal distention was improved with all drugs (Table), but constipation or transit was not. The percentage of patients with adverse effects did not differ for all drugs compared with placebo or for individual drugs.
Smooth-muscle relaxants improve the global rating of symptoms and reduce pain in patients with the irritable bowel syndrome.
Source of funding: In part, Solvay Pharmaceutical Company.
For correspondence: Dr. T. Poynard, Service d’Hépato-Gastroentérologie, Groupe Hospitalier Pitié-Salpêtrière 47-83, Boulevard de l’Hôpital 75651, Cedex 13, Paris, France. E-mail: firstname.lastname@example.org.
Table. Smooth-muscle relaxants vs placebo for the irritable bowel syndrome (trial duration 3 d to 24 wk)*
|Improvements||Drug||Number of studies||Unweighted event rates||RBI (95% CI)||NNT (CI)|
|Global||All||22||56%||38%||49% (37 to 61)||6 (5 to 8)|
|Mebeverine||4||52%||37%||47% (9 to 84)||4 (6 to 31)|
|Cimetropium||5||60%||40%||63% (29 to 92)||4 (3 to 9)|
|Trimebutine||4||53%||24%||98% (63 to 117)||5 (4 to 7)|
|Otilonium||3||97%||34%||60% (33 to 87)||5 (4 to 9)|
|Hyoscine||3||53%||42%||26% (7 to 124)||10 (2 to 32)|
|Pain||All||11||53%||41%||30% (16 to 45)||9 (6 to 16)|
|Otilium||3||47%||29%||62% (30 to 96)||7 (4 to 12)|
|Cimetropium||1||87%||27%||198% (81 to 253)||2 (2 to 5)|
|Distention||All||6||44%||35%||26% (6 to 46)||12 (7 to 46)|
*Abbreviations defined in Glossary; RBI, NNT, and CI calculated from data in article.
IBS represents a heterogeneous group of disorders presenting with similar clinical symptoms. Altered motility is thought to be important in a subset of patients with IBS, and this concept forms the foundation for the use of smooth-muscle relaxants.
3 recent meta-analyses, including the review by Poynard and colleagues, have evaluated smooth-muscle relaxants for IBS (1, 2). Each found such agents better than placebo for global improvement and abdominal pain. The latest, the review by Poynard and colleagues, differs from its predecessors by excluding peppermint oil and dyciclomide bromide and including 6 additional randomized, non-English-language trials. Although smooth-muscle relaxants appear superior to placebo, Poynard and colleagues suggest that only approximately 50% of treated patients will experience global improvement and only 40% will have an improvement in abdominal pain. In addition, the results do not indicate which individuals are most likely to improve with these agents. Perhaps most important, only 1 of the drugs included in this meta-analysis, hyoscine, is available in the United States, and it showed the least benefit for global improvement or abdominal pain over placebo.
If one accepts the issues noted above, it seems reasonable to conclude that as a class, smooth-muscle relaxants can benefit a subset of patients with IBS. Unfortunately, whether the results are generalizable to agents available to physicians in the United States remains an open question.
William D. Chey, MD
University of Michigan Health Systems
Ann Arbor, Michigan, USA
1. Poynard T, Naveau S, Mory B, Chaput JC. Meta-analysis of smooth muscle relaxants in the treatment of irritable bowel syndrome. Aliment Pharmacol Ther. 1994;8:499-510. [PubMed ID: 7865642]
2. Jailwala J, Imperiale TF, Kroenke K. Pharmacologic treatment of the irritable bowel syndrome: a systematic review of randomized, controlled trials. Ann Intern Med. 2000;133:136-47. [PubMed ID: 10896640]