LAUSR

&NA; A novel microdialysis‐dissolution/permeation (M‐D/P) system was developed for the biopharmaceutical assessment of oral drug formulations. This system consists of a side‐by‐side diffusion chamber, a microdialysis unit fixed within the dissolution chamber for continuous sampling, and a biomimetic Permeapad® as the intestinal barrier. In the M‐D/P system, the concentration of the molecularly dissolved drug (with MWCO <20 kDa) was measured over time in the dissolution compartment (representing the gastrointestinal tract) while the concentration of the permeated drug was measured in the acceptor compartment (representing the blood). The kinetics of both the dissolution process and the permeation process were simultaneously quantified under circumstances that mimic physiological conditions. For the current proof‐of‐concept study, hydrocortisone (HCS) in the form of slowly dissolving solvate crystals and buffer and the biorelevant fasted state simulated intestinal fluids (FaSSIF), were employed as the model drug and dissolution media, respectively. The applicability of the M‐D/P system to dissolution and permeation profiling of HCS in buffer and in FaSSIF has been successfully demonstrated. Compared to the conventional direct sampling method (using filter of 0.1–0.45 &mgr;m), sampling by the M‐D/P system exhibited distinct advantages, including (1) showing minimal disturbance of the permeation process, (2) differentiating “molecularly” dissolved drugs from “apparently” dissolved drugs during dissolution of HCS in FaSSIF, and (3) being less laborious and having better sampling temporal resolution. M‐D/P system appeared to be a promising, simple and routine tool that allows for the researchers' intensive comprehension of the interplay of dissolution and permeation thus helping for better oral formulation screening and as an ultimate goal, for better dosage forms assessment. Graphical abstract Figure. No caption available.