Safety and efficacy of danazol in immune thrombocytopenia: a systematic review

Background: The treatment landscape for relapsed or refractory immune thrombocytopenia (ITP) after corticosteroids is complex. Objectives: We aimed to assess the efficacy of danazol in treating ITP and evaluate the safety and adverse events following its administration. Methods: We searched the databases PubMed, EMBASE, and ClinicalTrials.gov for all published studies assessing danazol's efficacy and safety in treating ITP. The retrieved studies were screened by title and abstract, followed by full-text screening based on the eligibility requirements. The quality assessment was performed using a set of questionnaires. The data were extracted on the descriptive characteristics of the studies and participants, drug dosage, efficacy measures, and adverse effects, and the data were synthesized. Results: A total of 17 studies consisting of 901 participants were included. The overall response rate is around 61% in this analysis. Among the participants, 315 (34.9%) were men. The age of participants ranged from 16 to 86 years. Danazol combined with other pharmacologic interventions, including all-trans-retinoic acid or glucocorticoids, generated better results. The most common side effects appear to be liver injury and elevation of liver enzymes, weight gain, oligomenorrhea, amenorrhea, and myalgia. Conclusion: Danazol at low-to-medium doses was well tolerated and succeeded in improving ITP. Danazol therapy may be helpful in the treatment of chronic ITP that is corticosteroid refractory and when corticosteroids or splenectomy (or both) is contraindicated. Danazol can be considered for further research and development in treating primary immune thrombocytopenia.