Polyethylene Glycol-based Ointment Formulations of Alnus Sibirica Extract and Their Accelerated Stability Assessments

Ointment formulation development of Alnus sibirica extract (ASEx), a natural immunomodulator, has been limited because of instability problem. In this study, stabilized ASEx-containing ointments were developed using polyethylene glycol (PEG) base. By the Herschel-Bulkley model, the flow behavior indices were calculated as 0.410.97, indicating a shear-thinning flow. The PEG ointments were superior to other comparative formulation, white petrolatum-based ointment, in terms of moistness and removal capacity in a simplified sensory assessment by human volunteers. ASEx degradation followed first-order kinetics with temperature dependence. From accelerated stability assessments, a selective formulation (P3) was found to have longest shelf life of 527 days at 40 degrees C. Furthermore, by applying a Q(10) value of 2.17, the shelf life of P3 at 25 degrees C was estimated to exceed four years. Thus, we conclude that the P3 formulation may be an appropriate candidate for development of a commercial product with good long-term stability.