Fostamatinib

Fostamatinib, sold under the brand names Tavalisse and Tavlesse, is a tyrosine kinase inhibitor medication for the treatment of chronic immune thrombocytopenia (ITP). The drug is administered by mouth. Fostamatinib blocks the activity of the enzyme spleen tyrosine kinase (SYK). This enzyme is involved in stimulating parts of the immune system. By blocking SYK's activity, fostamatinib reduces the immune system's destruction of platelets, so allowing the platelet count to rise, which reduces the likelihood of excessive bleeding. The most commonly reported side effects are diarrhea, high blood pressure, nausea, respiratory infection, dizziness, increased liver enzymes, rash, abdominal pain, fatigue, chest pain and decreased white blood cell count. The U.S. Food and Drug Administration (FDA) considers it to be a first-in-class medication.