Predictivity of standardized and controlled permeation studies: Ex vivo - In vitro - In vivo correlation for sublingual absorption of propranolol.

In preclinical drug development, ex vivo and in vitro permeability studies are a decisive element for specifying subsequent development steps. In this context, reliability, physiological alignment and appropriate in vivo correlation are mandatory for predictivity regarding drug absorption. Especially in oromucosal drug delivery, these prerequisites are not adequately met, which hinders its progressive development and results in the continuous need for animal experiments. To address current limitations, an innovative, standardized, and controlled ex vivo permeation model was applied. It is based on Kerski diffusion cells embedded in automated sampling and coupled to mass spectrometric quantification under physiologically relevant conditions. This study aimed to evaluate the predictivity of the developed model using porcine mucosa (ex vivo) in relation to data of sublingual propranolol absorption (in vivo). In addition, the usefulness of biomimetic barriers (in vitro) as a replacement for porcine mucosa was investigated. Therefore, solubility and permeability studies considering microenvironmental conditions were conducted and achieved good predictivity (R = 0.997) for pH-dependent permeability. A multiple level C correlation (R ≥ 0.860) between obtained permeability and reported pharmacokinetic animal data (AUC, C) was revealed. Furthermore, a point-to-point correlation was demonstrated for several sublingual formulations. The successful IVIVC confirms the standardized ex vivo model as a viable alternative to animal testing for estimating the in vivo absorption behavior of oromucosal pharmaceuticals.