In preclinical studies, the compound was shown to interact selectively with the thrombopoeitin receptor, leading to activation of the JAK-STAT signaling pathway and increased proliferation and differentiation of megakaryocytes. Animal studies confirmed that administration could increase platelet counts. In 73 healthy volunteers, higher doses of eltrombopag caused larger increases in the number of circulating platelets without tolerability problems.
Eltrombopag has been studied, and shown to be effective, in two major clinical syndromes: idiopathic thrombocytopenic purpura and cirrhosis due to hepatitis C (in which low platelet counts may be a contraindication for interferon treatment). After 6 weeks of therapy in a phase III trial, eltrombopag 50 mg/day was associated with a significantly higher response rate than placebo in adult patients with chronic ITP.
^Bussel JB, Cheng G, Saleh MN, Psaila B, Kovaleva L, Meddeb B et al. (Nov 2007). "Eltrombopag for the treatment of chronic idiopathic thrombocytopenic purpura". The New England Journal of Medicine357 (22): 2237–2247. doi:10.1056/NEJMoa073275. PMID18046028.CS1 maint: Date and year (link)
^McHutchison JG, Dusheiko G, Shiffman ML, Rodriguez-Torres M, Sigal S, Bourliere M et al. (Nov 2007). "Eltrombopag for thrombocytopenia in patients with cirrhosis associated with hepatitis C". The New England Journal of Medicine357 (22): 2227–2236. doi:10.1056/NEJMoa073255. PMID18046027.CS1 maint: Date and year (link)