Antispasmodics in irritable bowel syndrome - a hoary old chestnut?

According to current studies, irritable bowel syndrome (IBS) affects about 11% of the entire population.[1] It means that we, as doctors interested in gastroenterology, need to manage around 858 million people at any age all over the world. Overwhelming? The second bad news is that the disease is chronic. Unlike even cancers that are curable when detected early, IBS is not. Treatment options are also limited, with the most important recommendation being life philosophy change, which, needless to say, is difficult to implement. Indeed, IBS is irritable for both patients and doctors. In these circumstances, any new report on IBS treatment seems interesting. Unfortunately, most of the recent studies concern old methods. But, it does not mean they are worth little. Comparing two aged drugs, drotaverine and mebeverine, in this issue of the Journal, Rai and Nijhawan, provided us with new data thanks to different methods applied.[2]

It is well known that antispasmodics are a large, heterogeneous group of drugs with different mechanisms of action. Each of them should be properly studied to make a trustworthy recommendation. For example, we have excellent studies with a new drug with antispasmodic properties among others –peppermint oil, confirmed in a recently published systematic review and network meta-analysis.[3] Meanwhile, drotaverine and mebeverine were assessed only in single studies. While the former has been confirmed as effective, the latter has not.[45] Meta-analyses performed in 2010 and 2012 also failed to prove mebeverine's efficacy.[6] Despite a lack of proven efficacy, it is still one of the most widely used drugs for patients with IBS. Therefore, new research is always welcome even when it seems a bit insipid. Nevertheless, one concern for the study by Rai and Nijhawan is the lack of a placebo arm, providing an objective comparison of all substances. However, taking into account earlier considerations, we can assume that mebeverine by itself served as a placebo.[2] If we accept such an assumption, we will receive another valuable research evaluating the effectiveness of drotaverine, this time using the latest US FDA guidelines for IBS focused on patient-reported outcome measures. Taking into consideration the results of this study, the drug can be used primarily in a subgroup of patients with predominant pain or bloating as the symptoms of IBS. It is worth noting that IBS patients often have a reduced quality of life (QoL), and improving it is one of the key priorities. Rai and Nijhawan showed that drotaverine improves QoL what may determine the second indication for a drug. But that's about all there is.

Summarizing, I think that no further studies are needed. It is high time to conclude that we should distinguish facts from opinions, as most recent guidelines of the American College of Gastroenterology did making the final recommendation and finding no indication for any antispasmodics to treat global IBS symptoms.[7]