Population bioequivalence statistical method based on earth mover′s distance for evaluation of particle size distribution consistency of ophthalmic emulsion

Population bioequivalence (PBE) is a statistical approach recommended by FDA to evaluate the consistency of particle size distribution of numerous nanoparticle products.However, when particle size distribution (PSD) profile exhibits multiple peaks or other complex distributions, the traditional descriptors D50 and SPAN are no longer suitable to describe PSD.Earth mover's distance (EMD) is a new statistical metric for assessing the difference between distributions.In this study, we used EMD to measure the discrepancy between PSD and then PBE was applied to perform statistical test to establish equivalence.Our results showed that the proposed method can effectively reject an unequivalent product and pass an equivalent product, thus indicating its helpfulness in guiding the optimization of formulation and preparation process.