A randomized, open-label, multicenter study to compare the efficacy and safety of terbutaline plus danazol compared to danazol monotherapy for the second-line treatment of adults with corticosteroid-resistant or relapsed primary immune thrombocytopenia (ITP).

The investigators are undertaking a parallel group, multicenter, randomized controlled trial of 228 adults with ITP in China. Patients were randomized to terbutaline plus danazol compared to danazol monotherapy group. Platelet count, bleeding and other symptoms were evaluated before and after treatment. Adverse events are also recorded throughout the study.

Inclusion Criteria: Patients >18 years old with corticosteroid-resistant or relapsed ITP who had either a platelet count of <30×10^9/L or a platelet count of <50×10^9/L and clinically significant bleeding.

1. Not achieving a sustained response to therapy with full-dose corticosteroids for a duration of at least 4 weeks or relapsed during the process of corticosteroid tapering or discontinuation;
2. Platelet counts <30×10^9/L or platelet counts < 50×10^9/L and significant bleeding symptoms (WHO bleeding scale 2 or above);
3. Willing and able to sign written informed consent.

Exclusion Criteria:

1. Pregnant or lactating women;
2. Secondary ITP (have a known diagnosis of connective tissue diseases, malignancy, active infection, HIV infections or hepatitis B virus or hepatitis C virus infections);
3. Received drugs affecting the platelet counts within 6 months before the screening visit (e.g., chemotherapy, anticoagulants, etc);
4. Severe medical condition (lung, heart, hepatic or renal disorder);
5. Patients who are deemed unsuitable for the study by the investigator.
6. Patients who had hypertension, diabetes mellitus, hyperthyroidism or coronary heart disease.