Old and New Treatments for Irritable Bowel Syndrome: Effective or Not?
Abstract & Commentary
By Bridget S. Bongaard, MD, FACP. Dr. Bongaard is Director of the NorthEast Internal & Integrative Medicine Program, CMC-NorthEast Medical Center in Concord, NC; she reports no financial relationships to this field of study.
Synopsis: This article was a systematic review and meta-analysis of high-quality randomized controlled trials determining the effect of fiber, antispasmodics, and peppermint oil in the treatment of irritable bowel syndrome, and demonstrating superiority of the three examined therapeutic modalities as compared to placebo.
Source: Ford AC, et al. Effect of fibre, antispasmodics, and peppermint oil in the treatment of irritable bowel syndrome: Systematic review and meta-analysis. BMJ 2008:337:a2313; doi: 10.1136/bmj.a2313.
Prominent international gastrointestinal authorities from six different institutions pooled their assessments of the available literature on treatment options for irritable bowel syndrome (IBS), spanning the years 1950 to April 2008, and combing both English and foreign papers. The selected randomized controlled trials were required to compare fiber, antispasmodics, and peppermint oil with placebo or no treatment in adults older than 16 years of age, excluding patients with organic or other functional gastrointestinal disorders. The goal was to determine whether the modalities rendered for at least one week (to allow achievement of steady state plasma concentrations of the agents) produced either a "global assessment of cure" or improvement of symptoms, or cure or improvement of abdominal pain after treatment.
Twelve studies, containing a total of 591 patients, analyzing fiber vs placebo or no treatment, were found to be acceptable. An array of fiber agents were studied: Dietary fiber and cereals, psyllium/ispaghula, karaya gum, and wheat bran were manifest in the individual studies. This notably includes both soluble and insoluble fiber compounds. Despite the diversity of the products tested, surprisingly, the therapeutic effectiveness was limited to the use of ispaghula/psyllium and not other more common dietary fiber agents utilized in clinical practice.
Twenty-two randomized controlled trials including 1,778 patients, met the criteria for evaluating the effectiveness of various prescribed antispasmodics vs placebo. Again a wide variety of antispasmodic agents were assessed, including: mebeverine, alverine, trimebutine, pinaverium, otilonium, cimetropium, hyoscine, dicycloverine, pirenzipine, prifinium, propinox, and rociverine. Only hyoscine (three trials, 426 patients) and otilonium (four trials totaling 435 patients) showed consistent evidence of efficacy.
Four trials compared peppermint oil or colpermin (the active compound in peppermint oil) with placebo in 392 patients. Both compounds achieved efficacy status in comparison to placebo.
Commentary
Irritable bowel syndrome is a common, chronic, relapsing health care issue, not only in the symptomatic experience of the patient, but also in terms of health care system resource strain (multiple expensive diagnostic tests required for exclusion of organic disease, frequent doctors visits, medication expense, and hospitalizations for unrelenting problems). Health care providers and patients alike need an effective and inexpensive strategy to successfully address the problem.
International guidelines and protocols for irritable bowel syndrome are conflicting or equivocal in their recommendations for these three commonly used agents. Traditionally, patients were first instructed to increase dietary fiber to increase intestinal transit time and stool bulk, and, if not efficacious, an antispasmodic prescription was utilized to decrease the symptoms of pain and bloating. Only recently has peppermint oil, an inexpensive over-the-counter treatment for IBS, been utilized as an antispasmodic therapeutic option. The particular best choice for fiber or medication had not been studied; however, this large meta-analysis steps up to offer best therapeutic suggestions.
The study concluded that fiber type mattered in effectiveness of treatment of IBS. Wheat bran was no more efficacious than placebo or a low-fiber diet, and using ispaghula/psyllium did provide improvement over placebo, though many patients had persistent symptoms. Both however confer health benefits as the insoluble fibers increase fecal bulk and decrease intestinal transit time with the resultant potential for increased colonic mucosal health,1 while the water-soluble fiber supplements promote laxative effects and consequently metabolic benefits. Choosing the correct agent for the patients' clinical symptom complex is critical. Unfortunately, in the meta-analysis only three of the trials reviewed specified the IBS variety treated (constipation, diarrhea, mixed variety). It is therefore difficult to extrapolate which patient population would most benefit from water-soluble fiber, though generally it did improve symptoms. One can therefore make the argument that it should be initiated in any of the IBS subtypes, but with a caution that patients should notify their health care provider if they experience more gas or discomfort.
The type of antispasmodics studied in the meta-analysis were myriad; however, not all are FDA-approved and available in the United States. Such is the case with the two agents recommended as most efficacious in the meta-analysis. Hyoscine and otilonium proved to be the best in class for symptom relief of bloating and pain; however, otilonium is available only in Indonesia, Mexico, Spain, Greece, Brazil, and Italy.
The adverse effects of these drugs need to be taken into consideration when being applied to patient care. They can cause dry mouth, dizziness, and blurred vision compared to placebo; however, in the trials studied, the relative risk of adverse events compared with placebo was 1.62, and none reported any serious adverse events with this class. Trimebutine seemed to have no benefit over placebo, while pinaverium, cimetropium, hyoscine, and otilonium significantly reduced the risk of persistent symptoms after treatment. It is therefore recommended that if one needs to add an antispasmodic to the patient's IBS regimen after water-soluble fiber, that the first choice be hyoscine, followed by one of the other available medications if hyoscine is not effective in symptom management.
There were no trials evaluated in this meta-analysis comparing peppermint alone either to the sole use of prescription antispasmodics or the singular use of water-soluble fiber. This analysis only addressed the use of the oil opposed to placebo, and this was made somewhat difficult by the inability to mask the smell and taste of the active treatment. Also, the four peppermint trials totaled a patient population less than either of the other two trial agents, so it is difficult to make firm recommendations with the limited data presented. Nonetheless, the studies were of good quality and all indicated that peppermint oil was more effective than placebo.
Peppermint oil decreases smooth muscle spasm, and diminishes colonic contractility and pain due to its calcium channel blocking activity. It is a safe and effective part of the IBS regimen, is an inexpensive alternative to antispasmodic medications, or may be used adjunctively if these medications do not completely dispel the IBS symptoms. Interestingly, peppermint oil can be administered to children with IBS. Buckle,2 a noted aromatherapy expert, refers to a study by Kline et al using enteric-coated gelatin capsules containing peppermint oil in the treatment of 50 children in a controlled multicenter study.3 Eight children withdrew for various reasons; however, 76% of the peppermint group showed significant reduction in symptoms compared to 43% in the placebo group. There were no side effects noted, nor change in stool consistency.
More research needs to be done to further clarify the effects of these three treatments in relation to the three subtypes of irritable bowel symptoms. Until that time, however, practitioners can feel confident that they can safely use these inexpensive modalities to help alleviate the suffering of irritable bowel syndrome, and break the cycle of pain and bloating.
References
1. Vuksan V, et al. Using cereal to increase dietary fiber intake to the recommended level and the effect of fiber on bowel function in healthy persons consuming North American diets. Am J Clin Nutr 2008:88:1256-1262.
2. Buckle J. Clinical Aromatherapy, Essential Oils in Practice. 2nd ed. St. Louis, MO: Elsevier Ltd.; 2003:140.
3. Kline RM, et al. Enteric-coated, pH-dependent peppermint oil capsules for the treatment of irritable bowel syndrome in children. J Pediatr 2001;138:125-128.
This article was a systematic review and meta-analysis of high-quality randomized controlled trials determining the effect of fiber, antispasmodics, and peppermint oil in the treatment of irritable bowel syndrome, and demonstrating superiority of the three examined therapeutic modalities as compared to placebo.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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