Prednisone 21-acetate is a derivative of prednisone, a synthetic corticosteroid exhibiting anti-inflammatory and immunosuppressive properties. It serves as both an active pharmaceutical ingredient in medical treatments and an intermediate in the synthesis of other corticosteroids. It is applied in managing inflammatory conditions such as arthritis, asthma, and allergic reactions; autoimmune diseases including lupus, multiple sclerosis, and Crohn's disease; oncology as part of chemotherapy to reduce inflammation; dermatology for severe skin disorders like eczema and psoriasis; and in preventing organ transplant rejection. In pharmaceutical chemistry, it acts as a key building block for developing advanced glucocorticoids with improved efficacy and fewer side effects.