onsdag 13 april 2011

Rifaximin - minimal förbättring jämfört med placebo

Det är mycket skriverier kring Rifaximin (Xifaxan) just nu. Inte minst på ibs siterna. Vissa läkare verkar se detta "mirakelmedel" som det nya "mirakelmedlet Zelmac aldrig var". Man ska fråga sig både en och två gånger - även om antibiotika tar död på en massa bakterier och minskar symtomen tillfälligt - vad händer i det långa loppet? Att käka antibiotika dagligen år ut och år in är knappast att rekommendera.. även om Rifaximin sägs verka lokalt i tarmen påverkar ju tarmhälsan hela kroppen. Vårt immunförsvar sitter bla i tarmen och vad händer då när vi gång på gång slår ut det? Det är inte bara de onda bakterierna som stryker med..

Frågan är om Rifaximin verkligen är ett bra alternativ vid IBS. Vad IBS nu innebär? Det kan ju uppenbarligen vara allt från lite ont i magen till en fullgången crohns. Det är läkarna som bestämmer och vi patienter som bestraffas. Min läkare har, till exempel ingen diagnoskod för de besvär jag lider av - alltså hamnar jag under slasktratten IBS - och många med mig. Irriterade tarmar, jo tjena.. vad säger det egentligen? Inte mycket. Bara att nåt är galet med tarmen och att läkarna inte vet hur de skall lösa problemet. Tyvärr.

Detta var vad som sades i senaste nyhetsmailet från http://www.helpforibs.com/  om Rifaximin och IBS. Döm själva!

Recently, there has been a lot of confusion surrounding antibiotics and IBS. Many people with IBS have had bad experiences with antibiotics of all kinds. The drugs often cause GI side effects and can make IBS symptoms much worse. But lately, there has been a flurry of news and research suggesting that a specific antibiotic might actually help IBS. What's all this about? ~ Heather
In
part one of our special series on antibiotics and IBS, we covered the bad guys.

Traditionally, broad-spectrum antibiotics (prescribed for all kinds of infections, to children and adults alike) often cause mild to severe gastrointestinal side effects, even for people who don't have IBS. This is because those drugs not only kill the bacteria causing the infection you're treating, but they also kill the friendly bacteria, called "flora", that live in your intestines.

These friendly bacteria normally regulate the consistency of stools and help with digestion. There is a growing mountain of research that this gut flora is actually of critical importance not just for bowel health, but overall disease resistance as well.

However, an antibiotic called Rifaximin (brand name Xifaxan) was recently reviewed by the FDA as a treatment for IBS - specifically, for bloating, abdominal pain, and diarrhea. What's going on?

Rifaximin is a broad-spectrum non-systemic antibiotic, which means that little of the drug will pass through the gastrointestinal wall into circulation. It has been approved by the FDA and prescribed for years for preventing and treating traveler's diarrhea caused by E. coli, and has few side effects with this use.

Over the past several years, Rifaximin has also been studied in several clinical trials as a treatment for non-constipation IBS, with some interesting results. One of the lead researchers, Dr. Mark Pimentel of Cedars-Sinai Medical Center in California, has been a strong proponent of Rifaximin and has gone so far as to say he believes that the "missing link," or root cause of most IBS symptoms, can actually be attributed to an overgrowth of bacteria in the small intestine.

In fact, initial studies of Rifaximin and IBS were based on the researchers' hypothesis that a large proportion of IBS patients had small intestinal bacterial overgrowth (SIBO). Initial studies actually reported SIBO in up to 80% of IBS patients.

However - as a rule, IBS should only be diagnosed when other disorders that can cause similar symptoms - including SIBO - have been ruled out. Unfortunately, diagnosing SIBO can be difficult. The most common diagnostic procedure, a hydrogen breath test, can have a high rate of false positives.

When subsequent IBS studies used the standard method of jejunal aspiration and bacterial culturing to diagnose SIBO, the small intestinal bacterial overgrowth was found in only 4% of IBS patients.

Clearly, this is a murky area of IBS. Small intestinal bacterial overgrowth (or SIBO) is normally considered to be a different disorder than IBS, even though the symptoms (abdominal pain, bloating, bowel dysfunction) are strikingly similar. Gastroenterologists vary wildly in their estimates of the number of people diagnosed with IBS who actually have undiagnosed SIBO. Making matters even murkier is the fact that it's possible for someone to have both SIBO and IBS. Some physicians have already begun to treat patients diagnosed with IBS for SIBO.

The most recent trials of Rifaximin, published in January 2011 in the New England Journal of Medicine, showed that the antibiotic achieved statistically better results than a placebo for treating non-constipation IBS - but not that much better.

In the Rifaximin group, 41% of patients reported adequate relief of IBS symptoms, versus 32% in the placebo group. In the Rifaximin group, 41% of patients reported adequate relief of bloating, versus 30% in the placebo group. Results were similar for at least 2 of the first 4 weeks of the trials, and in an analysis of relief of symptoms during the 10-week period after the end of the treatment.

An editorial by Jan Tack, M.D., Ph.D. that accompanied the study in the NEJM summarized the good news / bad news aspects of the trials:

Good - The sustained symptom improvements lasting at least 10 weeks, after a short treatment course, are encouraging.

Good -
Bloating was one of the symptoms successfully addressed, and bloating tends to be one of the most challenging aspects of IBS.

Bad - The rates of response to treatment are only 9% to 12% better with Rifaximin than placebo, which is in the lower spectrum of what's considered to be clinically relevant.

Bad - Though not all patients have a response with Rifaximin, data suggest that a subgroup of patients may have a substantial response. However, it's unclear how to identify this group.

Bad - IBS is a chronic disorder, and although Rifaximin's effects persisted after the 2-week treatment period, the response over time suggests that there is some loss of effectiveness with symptoms toward the end of the 10-week follow-up. It's not known whether patients would have a favorable response again with retreatment.

The FDA apparently shares some of these reservations about Rifaximin for IBS. In March 2011 they ruled that before the antibiotic can be approved for treating IBS, its manufacturer (Salix Pharmaceuticals) must provide data on how the drug should be used in retreating patients with recurrent symptoms.

So - should you try taking an antibiotic for IBS? This is a question worth asking your gastroenterologist, if you do not have constipation and you haven't responded to other treatments. Ask if there are generic antibiotics that might be comparable to Rifaximin (this may be a much more affordable option, and more likely to be covered by insurance). Ask if you've had the tests to rule out SIBO, and if so, what the results were.

Interestingly, probiotics are also being studied and, in some cases, recommended for both SIBO and IBS. This is also an area worth asking your doctor about, particularly since probiotics don't carry the risks and side effects of antibiotic drugs.

Finally, consider using a prebiotic soluble fiber to help encourage the growth of healthy gut bacteria naturally. This can help keep both IBS and SIBO symptoms under control.

~ Heather

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