Hyperprolactinemia in patients on antipsychotic drugs causes ADP-stimulated platelet activation that might explain the increased risk for venous thromboembolism: pilot study

Recently, an increased risk of venous thromboembolism in patients on antipsychotic drugs has been reported, but the molecular etiology is still unknown. Most antipsychotic drugs act as dopamine antagonists, and some of them cause hyperprolactinemia. Hyperprolactinemia has recently been found to cause increased platelet activation via potentiating ADP effects on human platelets. We assessed prolactin values as well as ADP-stimulated and thrombin receptor activator 6-stimulated expression of the platelet activation marker P-selectin in 20 consecutive patients under therapy with antipsychotic drugs. We detected a significant correlation between prolactin values and ADP-stimulated P-selectin expression on platelets in patients on antipsychotic drugs, revealing a significant higher platelet stimulation in hyperprolactinemic patients on antipsychotic drugs than in normoprolactinemic controls. Therefore, hyperprolactinemia might be the yet unknown acquired risk factor in patients on antipsychotic drugs explaining the increased risk for venous thromboembolism in these patients.