Valproate-Induced Thrombocytopenia

Valproic acid (VPA), used for epilepsy and mood stabilization, can cause thrombocytopenia, especially at doses >1000 mg/day, in elderly patients, or when combined with antiplatelet drugs. Thrombocytopenia, defined by a platelet count <150 × 10^9/L, affects 5-54% of patients and can lead to serious bleeding. It typically develops within 1-2 weeks of starting VPA and is more common in women. Mechanisms include direct bone marrow toxicity and autoantibody induction against platelets. Regular monitoring of platelet counts is crucial, particularly in high-risk groups, to manage this side effect.