Nucala 100mg Injection contains mepolizumab, a humanized monoclonal antibody targeting interleukin-5 (IL-5), indicated for the treatment of severe eosinophilic asthma. By selectively binding to IL-5, mepolizumab inhibits the growth, differentiation, recruitment, activation, and survival of eosinophils, thereby reducing airway inflammation and exacerbations associated with eosinophilic asthma. Nucala is administered via subcutaneous injection at a dose of 100 mg every four weeks. It is approved as an add-on maintenance treatment for patients aged 6 years and older with severe eosinophilic asthma inadequately controlled despite high-dose inhaled corticosteroids and additional asthma controllers. Clinical trials have demonstrated that Nucala significantly reduces the frequency of asthma exacerbations, improves lung function, and enhances quality of life. Additionally, Nucala is indicated for eosinophilic granulomatosis with polyangiitis (EGPA) and hypereosinophilic syndrome (HES) in adults, where it helps control eosinophil-driven inflammation. Common adverse effects include headache, injection site reactions, and back pain. Prior to initiation, patients should be evaluated for parasitic infections, as eosinophils play a role in host defense. Nucala should be administered under the supervision of a healthcare professional experienced in managing severe asthma or eosinophilic disorders.