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Some
Antidepressants
Increase Gastro Bleeding
Excerpt By Merritt McKinney, Reuters
Health
NEW
YORK (Reuters Health) - A widely prescribed class of antidepressant
drugs that act on the brain chemical serotonin increase the risk
of bleeding in the upper gastrointestinal (GI) tract, a study
from Canada indicates.
For most people,
however, the drugs are unlikely to cause any bleeding problems,
the study's lead author told Reuters Health in an interview.
The study
shows, according to Dr. Carl van Walraven at the University of
Ottawa, that antidepressants that act on serotonin ``are associated
with an increased risk of upper GI bleeding.''
``However,
this is only clinically significant for people greater than 80
and those with previous GI bleeding,'' he said. The researcher
advised that the risk of upper GI bleeding be considered when
treating depression in these groups of patients.
It may seem
odd that antidepressants would increase bleeding, since the drugs
are designed to work on the brain, not the GI tract. The connection,
van Walraven explained, is serotonin.
To battle
depression, Prozac and other SSRIs, or selective serotonin-reuptake
inhibitors, keep levels of serotonin high. Serotonin is not important
only to the brain, however. Van Walraven explained that blood
components called platelets use serotonin to help stop bleeding.
Since the
channel that platelets use to ``suck'' serotonin from the blood
is the same one the brain uses, some doctors began to wonder whether
SSRIs are ``messing up platelets,'' he said.
In the 1990s,
there were many reported cases of bruising and bleeding in patients
taking SSRIs, according to van Walraven. Then in 1999, a Spanish
study documented a link between SSRIs and an increased risk of
upper GI bleeding.
Some doctors
questioned the value of the study, however, since it did not take
into account that the extent of SSRI action on serotonin varies
from drug to drug.
In the September
22nd issue of the British Medical Journal, van Walraven and his
colleagues report the findings of a study that did take into account
the variable actions of antidepressants.
From 1992
to 1998, the researchers tracked a database of more than 300,000
people aged 65 and older who started taking an antidepressant
during the study. During that time, there were 974 hospital admissions
for upper GI bleeding.
The risk of
upper GI bleeding was highest in patients taking antidepressants
that had the most powerful effect on serotonin, although this
difference was not statistically significant.
The increase
in risk was significant, however, for people aged 80 and older
and those with a history of upper GI bleeding. The researchers
divided antidepressants into groups based on their action on serotonin.
They found that in older patients, the risk of bleeding increased
more than 10% per increase in class of drugs.
For people
aged 80 and older, the authors estimate that one additional episode
of upper GI bleeding will occur for every 244 patients treated
with an antidepressant that has a higher level of activity on
the serotonin system. For patients with a history of peptic ulcers,
the researchers expect an additional case of upper GI bleeding
for every 85 treated patients.
The study
shows that age and a history of GI bleeding should be taken into
account when selecting antidepressants, according to van Walraven.
But it is important not to focus too much on the small risks of
the drugs for most patients, he said.
``Side effects
are important, but we also have to consider the benefits,'' he
noted.
Referring
to the increased risk of bleeding, van Walraven said, ``for most
people, it is not clinically significant.''
He added that
patients taking antidepressants, even those who are elderly or
who have a history of GI bleeding, should not stop taking the
drugs without first consulting a physician.
In a statement
released in response to the study, Dr. Andrew Farah, of High Point
Behavioral Health and Wake Forest University in North Carolina,
advised physicians and patients ''not to jump to conclusions regarding
a possible risk of GI bleed in the elderly exposed to newer antidepressants.''
He noted that
the elderly are more likely to be prescribed medications called
nonsteroidal anti-inflammatory drugs (NSAIDs), which can increase
the risk of GI bleeding.
Farah also
said ``all antidepressants should not be painted with the same
brush,'' since the side effects and tolerability vary widely from
drug to drug. He also pointed out that the study did not include
newer antidepressants that are on the market or in the pipeline,
which he said are unlikely to increase the risk of GI bleeding.
Farah serves
as a consultant for GlaxoSmithKline and is on the speaker panels
of several other drug companies.
SOURCE:
British Medical Journal 2001;323:655-668.
Reference
Source 89
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