Influence of SSRI on blood coagulation

Nowadays, Selective Serotonin Reuptake Inhibitors (SSRI) are well established in psychopharmacological therapy. They have been shown to be very effective and having a favourable side effect profile. However, bleeding events are rare but there may be potentially severe complications under treatment with SSRI. These complications can occur under SSRI alone and in combination with anticoagulative drugs, whereas the coagulation parameters can remain unchanged. Pathophysiologically these bleeding complications are related to a reduced concentration of serotonin in the blood and pletelets. Reduction of serotonin, which occurs under treatment with SSRI, can lead to disturbances of platelet function and may also activate the fibrinolytic system. Both effects increase the risk of bleeding complications. In combination with anticoagulants, besides the serotonin-related bleeding events, additionally influences of SSRI on metabolism of the anticoagulative drugs due to their interactions with the Zytochrom-P450 system and changes of free plasma levels of the anticoagulative drugs, caused by a displacement from the plasma proteins through the SSRI, must be taken into consideration.