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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.
However, this is only clinically significant for people greater than 80 and those with previous GI bleeding. The researcher advised that the risk of upper GI bleeding be considered when treating depression in these groups of patients. They found that in older patients, the risk of bleeding increased more than 10%.
It may seem odd that antidepressants would increase bleeding, since the drugs are designed to work on the brain, not the GI tract. 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. 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."
In the 1990s, there were many reported cases of bruising and bleeding in patients taking SSRIs. Then in 1999, a Spanish study documented a link between SSRIs and an increased risk of upper GI bleeding.
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.
British Medical Journal September 22, 2001;323:655-668
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