Phase 1 clinical study of eltrombopag, an oral, nonpeptide thrombopoietin receptor agonist

Eltrombopag (SB-497 115) is a first-in-class, oral, small-molecule, nonpeptide agonist of the thrombopoietin receptor (TpoR), being developed as a treatment for thrombocytopenia of various etiologies. In this phase 1 placebo-controlled clinical trial in 73 healthy male subjects, 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 were dose dependent and linear, and eltrombopag increased platelet counts in a dose-dependent manner. There. were no apparent differences in the incidence or severity of adverse events in subjects receiving active or placebo study medication. These observations indicate that eltrombopag is a once-daily, oral TpoR agonist with demonstrated thrombopoietic activity in human subjects, encouraging further studies in patients with thrombocytopenia.