Eltrombopag is a new, orally active thrombopoietin-receptor (c-mpl) agonist that stimulates thrombopoiesis. Potential advantages of eltrombopag may include a sustained platelet response and a good tolerability profile.

Eltrombopag demonstrated a half maximal effective concentration (EC50) of 0.27 uM in murine BAF3 cells transfected with the luciferase reporter gene under direction of the STAT-activated IRF-1 promoter and human TpoR (BAF3/IRF-1/hTpoR) .

Eltrombopag stimulates the growth of TPO-dependent cell lines via JAK2 and STAT signaling pathways and stimulates isolated human CD34+ cells to become megakaryocytes and produce platelets in vitro.

Twelve weeks of antiviral therapy, with concurrent receipt of eltrombopag or placebo, were completed by 36%, 53%, and 65% of patients receiving 30 mg, 50 mg, and 75 mg of eltrombopag, respectively, and by 6% of patients in the placebo group.

Eltrombopag was administered as once-daily oral capsules for 10 days at doses of 5, 10, 25, 30, 50, and 75 mg. The pharmacokinetics of eltrombopag was dose dependent and linear, and eltrombopag increased platelet counts in a dose-dependent manner in vivo.

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2.McHutchison JG, et al. Eltrombopag for thrombocytopenia in patients with cirrhosis associated with hepatitis C. N Engl J Med. 2007,357(22):2227-36.