Ask the Pharmacist

Q) I hear there is a new drug that could help me better control my irritable bowel syndrome. What can you tell me about it?

A) Irritable bowel syndrome (IBS) is a very common diagnosis (it is estimated that as many as 1 in 5 Canadians suffer from this, with females twice as likely to be affected as males) that can significantly alter the quality of one’s life, although not the longevity.

We have all had the occasional bout of upset stomach along with gas and diarrhea that drags us down for the few days we must deal with it. For those with IBS, these sorts of symptoms persist, either intermittently or even daily for an unlucky few, throughout their adult lives.

IBS is called a functional disorder, in that all tests come back normal and there does not appear to be anything structurally wrong with any part of the intestines and yet the intestinal system still does not operate as it should. The most common symptoms include abdominal cramping, pain or bloating (that is typically relieved by having a bowel movement), excessive gas, diarrhea or constipation (or some patients cycle between the two states ) as well as the presence of mucus in the stools.

Treatment has consisted of a combination of lifestyle modifications (focused in particular on dietary modifications, better sleep habits, increasing exercise and learning how to better manage stress) along with the use of a growing number of drugs that address such issues as dysfunctional bowel motility (i.e. the rate at which your bowels transport food through the intestines), intestinal spasms as well as various laxatives and anti-diarrheals.

The newest drug that has been approved in Canada to help control the symptoms of IBS is called Zaxine. It has already been available for a number of years as a treatment option for hepatic encephalopathy, a possible serious complication for people with chronic liver disease.

Zaxine (its generic name is rifaximin) is classified as an antibiotic and it is thought to work by eliminating bacteria within the gut thereby reducing the intestine’s bacterial load and helping to restore its proper balance between the differing bacterial species. It is very poorly absorbed from the gut, which is a good thing in this case as it means the drug tends to exert most of its action where it is needed most thereby decreasing the risk of unintended consequences elsewhere in the body. It seems to provide lasting relief (more on that in a second) for symptoms including bloating, gas, abdominal pain, urgency, frequency and diarrhea (note, Zaxine should not be used in those with constipation predominant IBS). Approval for the drug was based on 2 studies comprising 600 patients in total that were placed on either Zaxine (in a tablet form) at a dose of 550mg three times a day for 2 weeks or on a placebo.

Following the course of therapy, participants were followed for 10 weeks afterwards. 40.7% of those taking Zaxine indicated that they felt their symptoms were adequately controlled by the treatment even weeks after stopping the pills (this is versus 30.3% who improved on the placebos, yet another reminder to never underestimate the power of positive thinking when it comes to improving one’s health) and with 40.2% saying their bloating was much improved, a significant event as bloating traditionally has been one of the symptoms that seems to be more difficult to alleviate.

Concerns include costs (a 2 week course costs about $350 and is not paid for by the government run drug plan for seniors), the fact that over half that respond to the treatment require another course within 6 months and theoretical concerns that there could be problems with developing antibiotic resistance if patient’s require multiple courses of therapy.

Possible side effects include, ironically enough, bloating and mild diarrhea, as well as dizziness, headache, itchiness, nausea and a reddish tinge to tears, sweat or urine. Rare but possible (they’re not really sure but patients are advised to look out for signs and symptoms of the following) complications from Zaxine include anemia and depression.

The drug is best taken on an empty stomach. Zaxine is going to be a good option for some people with IBS as some enrolled in the study indicated that they felt 80 to 90% better shortly after taking it. However, its role in the treatment of IBS with diarrhea is likely to be only as a secondary or fall back option for those who have not responded to other interventions due to some of the concerns we outlined earlier.

One other note, don’t underestimate the ability of psychotherapy to be of some benefit in treating IBS. Cognitive behaviour therapy has some decent evidence supporting it and if you’d really like to blow your mind look up the relatively new form of talk therapy called intensive dynamic short-term psychotherapy which looks really promising when it comes to helping people with real symptoms (IBS, pain, stomach issues, tremors…) for which there is no great medical explanation (here’s a link from a Globe and Mail article that touches upon it