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Bringing it all back home to
the IBS clinic
So how does this knowledge about
tega-serod translate to the clinical setting?
When seeing a newly diagnosed patient for the
first time, Dr John Marshall, a gastroenterologist
at Hamilton Health Sciences, says his first goal
is to educate them about what IBS — which
affects roughly 10% of Canadians, two-thirds of
them women — is and what it isn't. "First
of all, IBS is usually chronic," he explains,
"with symptoms waxing and waning over the years."
These symptoms include bouts of abdominal pain,
bloating and irregular bowel movements. He quickly
puts paid to the myth that IBS is a sign of something
more sinister, like cancer, which helps set patients'
minds at ease.
"People underestimate the impact
IBS has on people's quality of life," adds Dr
Marshall, which is why he emphasizes the importance
of managing IBS using the full range of therapeutic
— medical, dietary & lifestyle and psychological
— options.
Medical therapy: "Medical
treatment is symptom-oriented," explains Dr Mar-shall.
"The goal is to characterize and target the predominant
symptom." By definition, IBS is associated with
abdominal pain or discomfort which usually comes
in one of two forms: constipation or diarrhea.
The most com-mon approaches for tackling the symptoms
are listed below.
Constipation
- Fibre (wheat bran, up to
20g per day) and increased fluid intake
- Psyllium (soluble fibre)
- Serotonergic agent like
tegaserod
Diarrhea
- Loperamide (sold OTC as
Imodium)
Abdominal
pain
- Short-term
therapy with antispasmodic agents or peripheral
opiate antagonists
- Low-dose
tricyclic antidepressants in select patients
with frequent pain
- Serotenergic
agent like tegaserod (when present with constipation)
- Avoid narcotics
Diet & lifestyle:
While IBS isn't directly caused by diet or lifestyle,
IBS can be exacerbated by both. Many patients
associate IBS attacks with eating certain foods,
and will come in expecting dietary advice. Dr
Marshall recommends getting patients to keep a
symptom diary which can help highlight triggers;
common culprits are fatty foods, caffeine, lactose
and fructose. He adds that simple lifestyle changes
like a regular eating schedule and planning for
bathroom time can often help.
Psychological: "Psychotherapy
is undervalued and underutilized, even though
it may be a better longterm approach than pharmacotherapy,"
says Dr Marshall. He says doctors often have trouble
accessing proper services like cognitive behavioural
therapy, but "it's not feasible for the average
physician to embark on psychotherapy because it's
too time-consuming."
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Not long ago doctors believed irritable
bowel syndrome (IBS) was all in the patient's head;
these days it's widely accepted the debilitating disease
is actually all in the gut. Or, to be more precise,
it's all in the serotonin receptors on nerve cells in
the gut. And now the only IBS drug approved for use
in Canada, tegaserod, which was developed based on this
discovery, just got better. As good as it is on first
use, tegaserod's efficacy skyrockets with repeated use,
according to a study in the December issue of Gut.
BRAIN-GUT
LINK
About 95% of the body's serotonin lives in the gut where
it's vital not only to normal gut function, but to make
sure the gut and brain communicate properly. When researchers
went looking for the dysfunction behind IBS, they found
implicated changes in serotonin signalling. In the gut,
serotonin is involved in neuronal control of motility
and sensitivity. Tegaserod targets serotonin signalling
and is indicated for use in IBS patients whose main
symptoms are constipation and abdominal pain or discomfort.
In their study, Dr Jan Tack of
the University of Leuven in Belgium and colleagues tracked
first time treatment of 2,660 female patients with either
tegaserod or placebo. Relief of IBS symptoms was reported
by 34% of the treatment group and 24% of patients in
the control group. When treatment was repeated in 1,191
patients, relief from tegaserod rose to 45%; in the
placebo group relief remained fairly steady at 29%.
Confidence in tegaserod is growing
steadily. At the 13th United European Gastroenterology
Week held in Copenhagen in October where Dr Tack's findings
were presented, Professor Michael Kamm, a gastroenterologist
and IBS expert at St Mark's Hospital, London, spoke
glowingly about it and three other recent phase III
trials of the drug: "Clinical trial data demonstrate
that tegaserod rapidly and effectively relieves overall
IBS-constipation symptoms as well as individual symptoms
of abdominal pain, discomfort, bloating and constipation."
There is another serotonergic agent
out there: alosetron. But shortly after its approval
in 2000 it was withdrawn after a high number of patients
suffered bowel ischemia. The drug was allowed back on
the US market in 2002 with tight restrictions. It has
never received approval in Canada.
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