Study of a New Medication for Childhood Chronic Immune Thrombocytopenia (ITP), a Blood Disorder of Low Platelet Counts That Can Lead to Bruising Easily, Bleeding Gums, and/or Bleeding Inside the Body.

The purpose of this study is to investigate the efficacy, safety and tolerability of eltrombopag in children with previously treated chronic immune thrombocytopenia who are between 1 and 17 years of age. This is a 2 part study. In part 1, patients will be randomized to receive either eltrombopag or placebo for 13 weeks. All patients who complete part 1 will enter part 2. In part 2, all patients will receive 24 weeks of eltrombopag.

This is a two part, double-blind, randomized, placebo-controlled and open-label Phase III study to investigate the efficacy, safety and tolerability of eltrombopag in pediatric patients with previously treated chronic ITP. In Part 1, patients will be randomized to receive eltrombopag or placebo in a 13-week double-blind, placebo-controlled treatment period. After completing Part 1, patients will begin Part 2, in which they will receive eltrombopag in an open-label manner during a 24-week treatment period.