Abstract
PURPOSE: Irisin, a hormone secreted by skeletal muscle during physical exercise, shows promise for health benefits. However, limited research on its characterization and formulation development has impeded its pharmaceutical development. This study aimed to develop fit-for-purpose subcutaneous formulations for irisin. METHODS: Irisin was expressed in E.coli and purified. The prepared irisin was characterized using orthogonal biophysical techniques, and its biological activity was assessed. Subcutaneous formulations were then developed by screening pH, excipients, and formats (lyophilized vs. aqueous), and the product stability profiles were investigated under various conditions. RESULTS: Irisin was successfully expressed in both soluble and refolded forms, and after purification, both forms displayed similar biophysical properties and induced adipocyte browning. Lyophilized formulations, incorporating phosphate buffer (pH 7), sucrose or trehalose, and polysorbate 80, preserved irisin's properties and bioactivity after lyophilization and could be rapidly reconstituted for subcutaneous administration. The formulations also remained stable at 40°C/75% RH for at least one month. CONCLUSIONS: These findings lay a foundation for advancing irisin-based therapies for obesity and related diseases.