The Impact of Serotonin Transporter Binding Affinity on the Risk of Bleeding Related to Antidepressants

PURPOSE/BACKGROUND The alleged primary mechanism underlying bleeding events associated with antidepressants is inhibition of serotonin uptake in platelets resulting in reduced platelet aggregability and activity, and prolonged bleeding time. There is some evidence that a substance's degree of serotonin reuptake inhibition in terms of its binding affinity to the serotonin transporter (SERT) affects the magnitude of bleeding risk increase. METHODS/PROCEDURE To test this hypothesis, we performed data mining in the worldwide largest pharmacovigilance database (VigiBase) and conducted pharmacodynamically informed quantitative signal detection. Reporting odds ratios related to the standardized Medical Dictionary of Regulatory Activities query term "haemorrhages" and 24 antidepressants were calculated, and SERT binding affinities (pKi) were obtained and correlated (Pearson correlation). FINDINGS/RESULTS A strong and statistically significant correlation between substance-related reporting odds ratios and SERT binding affinities was found (r = 0.63; 95% confidence interval, 0.30-0.82; P = 0.00097). IMPLICATIONS/CONCLUSIONS Our findings strengthen the hypothesis that inhibition of serotonin uptake contributes to the antidepressant-related bleeding risk and suggest an association between the degree of the SERT binding affinity and the bleeding risk. This supports the preferential use of antidepressants with low or no SERT binding affinity in depressed patients at risk of bleeding.