DOCTOR'S VIEWS ARCHIVE
Topic: Irritable Bowel Syndrome (IBS), June 2000
Is alosetron effective in treating IBS?
Lotronex is the brand name for alosetron, the drug which is specifically for women
with irritable bowel syndrome who have diarrhea. It probably will be a model for future drugs in irritable bowel
syndrome, and I think it is worthwhile to discuss the way in which it works. The nerves of the bowel,
like other nerves, communicate with each other using chemical messengers or neurotransmitters. Nerves manufacture neurotransmitters and release
them. They travel and attach to other nearby nerves and change the way the nearby nerves function.
One of the theories for explaining
irritable bowel syndrome is that the nerves of the bowel are not
functioning correctly. Since the neurotransmitters control nerve function,
it is hoped that by augmenting or blocking the appropriate neurotransmitter,
normal function will be restored to the nerves. For example, alosetron
blocks the attachment of one neurotransmitter, 5 hydroxytryptamine, to
I have several women patients who experienced dramatic relief of their cramps and
diarrhea with low doses of alosetron. These women have had IBS for years and
have failed all other treatments. For them this drug is an absolute god-send.
On the other hand, I also have patients
whose bloating, diarrhea and cramps did not respond to
alosetron. Some of them developed severe and bothersome constipation even
with low doses of the drug. Has this been your experience too with this drug?
I think that is true, and that
is what the studies have shown so far, but that is not at all surprising
because we are dealing with a very complex disorder in which there are
many different types of functional problems that might be present. But the
origins, that is, what is causing those problems, may result in the same kinds of
symptoms, for example, abdominal pain or bloating.
I have also tried using alosetron in men with chronic symptoms of diarrhea and cramps. So
far I haven't had much success. Do you use this drug in men?
Well, in the 2 large trials that were done with alosetron, men did not participate because they do not
benefit from the treatment. It's use is approved only for women, and only in women with diarrhea.
You don't want to use alosetron on women
patients with constipation because the drug's main side effect is
constipation. So if a patient has constipation as part of their irritable
bowel it could get worse with alosetron. There even are reports of more serious complications from alosetron such as ischemic colitis and rupture of the colon that require surgery.
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Last Editorial Review: 6/19/2000 8:48:00 AM