Clinical Research Directory

Inclusion Criteria: 1. Age is above 15 years old. 2. Before randomization, the clinical diagnosis is primary immune thrombocytopenia. The platelet count is less than 30×10\^9 / L within 1 week before enrollment, or platelet count is less than 50×10\^9 / L with bleeding symptoms within 1 week before enrollment. 3. The antinuclear antibody is positive. 4. Other autoantibodies (mainly including dsDNA antibodies, SSA, SSB, RNP, β 2-GP, ACA, ANCA) are negative. 5. Participants who had received at least two HD-DXM 40 mg/d ×4 d, failed or relapsed, or received standard dose prednisone (1-2 mg/kg/d) for 4 weeks, the platelet count remained \<30×10 9 / L, or the platelet count normalized but decreased with prednisone tappering off, or prednisone 30mg to maintain the platelet number. 6. Prothrombin time does not exceed ± 3s of the normal value ranget, activated partial thrombin time is not outside normal range ± 10s; no history of coagulopathy except ITP. (6)Understand the study procedures and sign the written informed consent form. Exclusion Criteria: 1. Secondary thrombocytopenia caused by myelodysplastic syndrome, immune diseases such as systemic lupus erythematosus, early aplastic anemia, atypical reanemia, antiphospholipid syndrome, thrombotic thrombocytopenic purpura and various other causes. 2. The participant has experienced any arterial or venous thrombosis (stroke, transient ischemic attack, myocardial infarction, deep vein thrombosis or pulmonary embolism), or clinical symptoms and medical history indicate thrombophilia. 3. Congestive heart disease, including New York Heart Association (NHYA) Grade III / IV, occurred within 3 months prior to screening, arrhythmia requiring medication or myocardial infarction, or arrhythmia known to increase the risk of thrombotic events (such as atrial fibrillation), or corrected QT interval (QTc) is longer than 450 ms, or QTc\> 480 ms in paricipants with bundle branch block. 4. A medical history of parenchymal organ transplantation or allogeneic bone marrow transplantation. 5. Having received any medication affecting platelet function ( Including but not limited to aspirin, aspirin-containing complexes, clopidogrel, salicylates, and / or non-steroidal anti-inflammatory drugs NSAIDs ) or anticoagulant therapy for over consecutive 3 days within 2 weeks before screening. 6. With Glucose-6-phosphate dehydrogenase deficiency. 7. With retinal or visual field changes caused by 4-aminoquinoline compounds. 8. Being allergic to 4-aminoquinoline compounds. 9. Having evidence of Human Immunodeficiency Virus (HIV)/ hepatitis C virus(HCV)/ hepatitis B virus(HBV) infection (HIV antibody or HCV antibody is positive, HBV surface antigen is positive, or HBV surface antigen is negative but HBV-DNA indicating viral replication. 10. Glutamate transaminotransferase (ALT) or glutamate transaminase (AST) is higher than 1.5 times the upper limit of normal value (ULN), or total bilirubin or blood creatinine is higher than 1.2 times the ULN. 11. With liver cirrhosis or portal hypertension. 12. With evidence of malignant tumor activity, or receiving anti-tumor treatment within 5 years prior to the screening. 13. Participants being pregnant or lactating, or with potential fertility, reluctance to use effective contraception within the entire trial cycle and within 28 days after the end of the trial (or within 28 days after premature withdraw).