Determining bioequivalence possibilities of long acting injectables through population PK modelling

Long acting injectables (LAI) products are a popular intervention for treating a number of chronic conditions, with their long drug release reducing the administration frequency and thus improving patient adherence. The extended release, however, can provide a major challenge to bioequivalence (BE) testing since the long absorption half-life results in a long washout period, meaning that a traditional BE study can be many months or years in length. The unique PK profile for LAI products also means that it is critical to have appropriate metrics to summarise the plasma concentration profile. In this work, we use paliperidone as a case study to demonstrate how Population PK modelling can be utilised to explore sensitivity of summary metrics to different products. We also determine a range of products that are bioequivalent after both multiple dosing and single dosing. Finally, we show how the modelling can be used in a (virtual) PK study as an alternative approach to determining bioequivalence. This work demonstrates the potential for Population PK modelling in bioequivalence assessment, opening doors to more streamlined product development.