Dissolution/permeation: The importance of the experimental setup for the prediction of formulation effects on fenofibrate in vivo performance.

The evaluation of formulation strategies in early drug development requires in vitro methods that correctly predict oral drug absorption. The present study aimed to define key parameters for the predictability of dissolution/permeation experiments. Dissolution/permeation experiments were performed in various setups. The IDAS1 chamber, Ussing chamber, and transwells were used as Caco-2 cell based dissolution/permeation models to study the impact of chamber volumes and vertical or horizontal membrane orientation. Dissolution/permeation experiments in Ussing chambers with excised rat intestine were performed to depict the impact of the permeation membrane. Fenofibrate served as model compound in formulations of different particle size. Caco-2 cell based dissolution/permeation experiments with a vertical membrane orientation correctly depicted the formulation effect seen in vivo. The chamber volumes did not affect the outcome. A horizontal membrane orientation achieved no distinction. Experiments using excised rat intestinal sheets did not distinguish between the formulations, and the permeation was much lower than across Caco-2 cells. Mucus might present an artificially enhanced barrier for fenofibrate. Factors that greatly affected the predictivity of the dissolution/permeation experiments were thus the type and orientation of the permeation membrane, whereas chamber volumes only had a minor influence. Vertically mounted Caco-2 cells resulted in the best formulation distinction.