Selection of Pharmaceutical Antioxidants by Hydrodynamic Voltammetry

Antioxidant compounds are routinely included in pharmaceutical formulations in order to minimize the oxidative degradation of the active pharmaceutical ingredient(s) (API). The effectiveness of the antioxidants being considered is often assessed by creating several formulations with the API(s) and single or multiple antioxidants in order to place each of these formulations on stability under accelerated conditions. This trial and error selection process is costly and time consuming, often taking weeks before the oxidation is observed at a detectable level. Using a flow injection coulometric detector based system, a potential tool has been developed to guide initial antioxidant selection for hindering the oxidative degradation for a given drug substance in its formulation environment. The relative potential for the API to be oxidized can be measured by matching the conditions of the coulometric experiment to the formulation matrix. Using this selection criterion, the choice of antioxidants to study for individual formations can be greatly narrowed, thus leading to a significant savings in development time and cost.