From the Research
Aspirin (acetylsalicylic acid) 81 mg daily typically begins to reduce platelet count within 1-3 days in patients with thrombocytosis, with more significant effects observed within 7-10 days of consistent use. The full antiplatelet effect generally stabilizes after about two weeks of daily therapy. This relatively rapid response occurs because aspirin irreversibly inhibits the enzyme cyclooxygenase-1 (COX-1) in platelets, preventing thromboxane A2 production and reducing platelet aggregation. Since platelets cannot synthesize new proteins after they're released into circulation, the inhibitory effect lasts for the entire lifespan of the affected platelets (approximately 7-10 days) 1. The therapeutic effect is cumulative as more platelets become affected with continued dosing. For patients with essential thrombocythemia or other myeloproliferative disorders causing thrombocytosis, low-dose aspirin is often used long-term to reduce thrombotic risk. Regular monitoring of platelet count and function is recommended during the first few weeks of therapy to assess response and adjust treatment if necessary.
Some key points to consider:
- The effect of aspirin on platelet count and function can vary depending on the individual patient and the specific characteristics of their thrombocytosis 2.
- Twice-daily dosing with low-dose aspirin may provide a more consistent platelet inhibition compared with standard once-daily dosing in patients with essential thrombocythemia 3.
- The choice of aspirin formulation and dosing regimen should be individualized based on the patient's specific needs and risk factors 1.
- Cytoreductive treatment, such as hydroxycarbamide or pegylated interferon alpha, may also affect platelet function and turnover in patients with essential thrombocythemia 2.
Overall, the use of aspirin in patients with thrombocytosis requires careful consideration of the individual patient's needs and risk factors, as well as regular monitoring of platelet count and function to assess response and adjust treatment as necessary.