Study of AKR-501 Tablets Taken Orally Once Daily for 28 Days in Patients With Chronic Idiopathic Thrombocytopenic Purpura (ITP)

This is a Phase 2, multi-center, double-blind, randomized, placebo-controlled, dose-ranging, parallel-group study. The pharmacokinetic (PK) and pharmacokinetic/pharmacodynamic (PK/PD) relationship of avatrombopag will also be studied. Approximately 65 eligible participants will be randomized in a 3:3:3:3:1 ratio in a double-blinded fashion into one of five parallel treatment groups to receive daily doses of either avatrombopag 2.5, 5, 10 or 20 mg or placebo for 28 days, respectively. Each avatrombopag dosing group will consist of 15 participants while the placebo group will consist of 5 participants. All study participants will be evaluated weekly (Days 3, 5, 7, 14, 21 and 28) for safety, efficacy, and (Days 7, 14, 21, and 28) avatrombopag PK while receiving study treatment with a final assessment for safety and effectiveness to be done 2 weeks after the last study dose (Day 42). At the completion of Visit Day 28±1, participants who complete 28±1 days of study dosing will be assessed for eligibility to enroll into the rollover Study 501-CL-004 (NCT00625443) based on this visit.