Selective Serotonin Reuptake Inhibitors Influence Agonist-Induced Platelet Aggregation. Preliminary Results from Comorbidity of Depression and Cardiovascular Disease Study

Selective serotonin reuptake inhibitors (SSRI) are a first-line treatment option for depressive illnesses, anxiety and obsessive-compulsive disorders with a favorable risk benefit ratio and side effects. They selectively inhibit neuronal reuptake of serotonin and result in depleted serotonin stores in the dense bodies of platelets. It is hypothesized that depressive illnesses cause platelet activation and endothelial dysfunction, which could be modulated by the use of SSRIs. In order to validate this hypothesis an institutional-based co morbidity of depression and cardiovascular study is undertaken. Patients with depression (n=25) and healthy control (n=25) are recruited in this study. Males and females between the ages of 20 and 65 years meeting the DSM-IV criteria for major depressive disorder served as the inclusion criteria for the study. The exclusion criteria included patients with heart disease, diabetes, lipid disorders, history of smoking, pregnant and lactating women, psychosis, schizoaffective illnesses and presence of other Axis I diagnosis with the exception of generalized anxiety disorder. Blood samples were collected at baseline and then 4 and 8 weeks following treatment with Escitaloprim, an SSRI. Preliminary results from the agonist-induced platelet aggregation showed varying degrees of inhibition of collagen, ADP, arachidonic acid and epinephrine-induced platelet aggregation as shown in the table below. Agonist induced platelet aggregation profile Averaged % aggregation Time Collagen AA ADP Epinephrine Saline Baseline 71.5± 22.4 64.1± 35.1 48.15± 30.9 55.65± 29.2 6.9± 4.5 Week 4 63.4± 19.5 67.1± 25.1 33± 26.7 37.375± 25.8 9.375± 7.8 Week 8 74.7± 21.3 55.71± 36.1 52.4± 31 50.4± 32.3 5± 3.9 While a number of patients showed an inhibition of ADP (2.5μM) and epinephrine (10μg/ml) and collagen (380μg/ml), however, other patients showed an inhibition of collagen-induced platelet aggregation. These results indicate that patients treated with SSRIs may have inhibition of platelet activation and aggregation, which may have an impact in the prevention of atherothrombotic cardiovascular disease. SSRIs might increase the bleeding tendency in some patients by inhibiting platelet aggregation. However, when the SSRIs are given in combination with other drugs patients may have a propensity for bleeding complications due to drug-drug interactions. Further large-scale trials are warranted to validate these results.