SSRIs and gastrointestinal bleeding

Sir,
I read with interest the article by Carol Paton and Prof Ferrier, on SSRI
and GI bleed (1) . The authors note that there is an association between
SSRI and GI bleed. On reading the article, few queries did pop into my
mind.

1. The authors state that the mechanism of action by which SSRIs and
NSAIDs cause GI bleed differ. SSRIs acting centrally on the platelets and
NSAIDs acting peripherally on the mucosa. My query is, Serotonin being
present through out the gut, could the SSRIs have local action on the
mucosa as well? If not, how can SSRIs cause bleeding if the mucosa/ vessel
wall is intact? And why specifically GI bleed?

2. The authors note that studies have shown an association between
transporter affinity and GI bleed. One of the studies they quote (2), show
that the risk of bleed was most with Trazodone. Trazodone having weak
effect on the serotonin reuptake mechanism. This may mean that the action
of the various drugs may not be restricted to the reuptake mechanism, but
may be multifactorial.

3. The authors very rightly point out that Gastroprotective agents
may not be useful for patients only on SSRIs. This may be because SSRIs
induce nausea and vomting, through their action on the 5HT3 receptors at
the Chemoreceptor trigger zone, which may lead to secondary gastritis,
thus increasing the risk for a bleed.

[1]Paton C & Ferrier IN. SSRIs and gastrointestinal bleeding. BMJ
2005;331;529-30

[2]De Abajo FJ, Rodriguez AG, Montero D. Association between
selective serotonin reuptake inhibitors and upper gastrointestinal
bleeding. BMJ 1999;319: 1106-9.

Competing interests:
None declared