Understanding peroxide formation in Tween® 80 using RapidOxy®: Implications for pharmaceutical nanoemulsions

The oxidation stability of Tween® 80, a widely used surfactant in pharmaceutical formulations, was analyzed in-depth to predict its shelf life under pharmaceutical stability conditions. This study aimed to determine the influence of oxidative degradation on the stability of nanoemulsions (NEs) by assessing peroxide formation as a marker of oxidation. By correlating the amount of oxygen absorbed with the oxidation level, a novel mathematical approach was proposed to estimate real-time shelf-life predictions, specifically determining the time required to reach a peroxide value of 10 (mEq O₂)·kg^-1. Furthermore, nanoemulsions prepared with Tween® 80 at varying levels of oxidative degradation were analyzed. While no significant differences were observed in the overall properties (droplet size, polydispersity index) of these formulations compared to the control, a slight increase in zeta potential and partial degradation of the active pharmaceutical ingredient (API) were detected when oxidized Tween® 80 was used. These findings suggest a potential impact on system stability, emphasizing the need for further long-term investigations to fully understand the implications of oxidative degradation on pharmaceutical nanoemulsions.